1
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Lynch P, Das A, Alam S, Rich CC, Frontiera RR. Mastering Femtosecond Stimulated Raman Spectroscopy: A Practical Guide. ACS PHYSICAL CHEMISTRY AU 2024; 4:1-18. [PMID: 38283786 PMCID: PMC10811773 DOI: 10.1021/acsphyschemau.3c00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 01/30/2024]
Abstract
Femtosecond stimulated Raman spectroscopy (FSRS) is a powerful nonlinear spectroscopic technique that probes changes in molecular and material structure with high temporal and spectral resolution. With proper spectral interpretation, this is equivalent to mapping out reactive pathways on highly anharmonic excited-state potential energy surfaces with femtosecond to picosecond time resolution. FSRS has been used to examine structural dynamics in a wide range of samples, including photoactive proteins, photovoltaic materials, plasmonic nanostructures, polymers, and a range of others, with experiments performed in multiple groups around the world. As the FSRS technique grows in popularity and is increasingly implemented in user facilities, there is a need for a widespread understanding of the methodology and best practices. In this review, we present a practical guide to FSRS, including discussions of instrumentation, as well as data acquisition and analysis. First, we describe common methods of generating the three pulses required for FSRS: the probe, Raman pump, and actinic pump, including a discussion of the parameters to consider when selecting a beam generation method. We then outline approaches for effective and efficient FSRS data acquisition. We discuss common data analysis techniques for FSRS, as well as more advanced analyses aimed at extracting small signals on a large background. We conclude with a discussion of some of the new directions for FSRS research, including spectromicroscopy. Overall, this review provides researchers with a practical handbook for FSRS as a technique with the aim of encouraging many scientists and engineers to use it in their research.
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Affiliation(s)
- Pauline
G. Lynch
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Aritra Das
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Shahzad Alam
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher C. Rich
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Renee R. Frontiera
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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2
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Krueger TD, Henderson JN, Breen IL, Zhu L, Wachter RM, Mills JH, Fang C. Capturing excited-state structural snapshots of evolutionary green-to-red photochromic fluorescent proteins. Front Chem 2023; 11:1328081. [PMID: 38144887 PMCID: PMC10748491 DOI: 10.3389/fchem.2023.1328081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 11/24/2023] [Indexed: 12/26/2023] Open
Abstract
Photochromic fluorescent proteins (FPs) have proved to be indispensable luminous probes for sophisticated and advanced bioimaging techniques. Among them, an interplay between photoswitching and photoconversion has only been observed in a limited subset of Kaede-like FPs that show potential for discovering the key mechanistic steps during green-to-red photoconversion. Various spectroscopic techniques including femtosecond stimulated Raman spectroscopy (FSRS), X-ray crystallography, and femtosecond transient absorption were employed on a set of five related FPs with varying photoconversion and photoswitching efficiencies. A 3-methyl-histidine chromophore derivative, incorporated through amber suppression using orthogonal aminoacyl tRNA synthetase/tRNA pairs, displays more dynamic photoswitching but greatly reduced photoconversion versus the least-evolved ancestor (LEA). Excitation-dependent measurements of the green anionic chromophore reveal that the varying photoswitching efficiencies arise from both the initial transient dynamics of the bright cis state and the final trans-like photoswitched off state, with an exocyclic bridge H-rocking motion playing an active role during the excited-state energy dissipation. This investigation establishes a close-knit feedback loop between spectroscopic characterization and protein engineering, which may be especially beneficial to develop more versatile FPs with targeted mutations and enhanced functionalities, such as photoconvertible FPs that also feature photoswitching properties.
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Affiliation(s)
- Taylor D. Krueger
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
| | - J. Nathan Henderson
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ, United States
| | - Isabella L. Breen
- School of Molecular Sciences, Arizona State University, Tempe, AZ, United States
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
| | - Rebekka M. Wachter
- School of Molecular Sciences, Arizona State University, Tempe, AZ, United States
| | - Jeremy H. Mills
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ, United States
- School of Molecular Sciences, Arizona State University, Tempe, AZ, United States
| | - Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
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3
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Ockelmann T, Hoberg C, Buchmann A, Novelli F, Havenith M. Energy Dissipation into the Solvent during Proton Transfer Occurs via Acoustic Phonons. J Phys Chem B 2023; 127:9560-9565. [PMID: 37879121 DOI: 10.1021/acs.jpcb.3c04874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
In photochemistry, rapid energy dissipation into the solvent is mandatory to prevent radiation damages. By optical pump THz spectroscopy, we are able to follow the details of the energy dissipation mechanism upon photoexcitation of the photoacid to the hydrogen-bonded network of water: Based on the frequency maps subsequent to photoexcitation, we propose that energy transfer takes place via propagation of an acoustic phonon. The dissipation into the solvent can be rationalized by an initial first hydration shell response followed by energy dissipation via an acoustic phonon. Surprisingly, for the first 10 ps, the propagation in the water network can be described by a wave packet with a constant group velocity, indicating a long-range correlation. After 300 ps, thermalization in the liquid jet is reached and the THz spectrum reflects a Boltzmann population, corresponding a temperature increase of ΔT = 0.5 °C.
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Affiliation(s)
- Thorsten Ockelmann
- Department of Physical Chemistry II, Ruhr University Bochum, 44780 Bochum, Germany
| | - Claudius Hoberg
- Department of Physical Chemistry II, Ruhr University Bochum, 44780 Bochum, Germany
| | - Adrian Buchmann
- Department of Physical Chemistry II, Ruhr University Bochum, 44780 Bochum, Germany
| | - Fabio Novelli
- Department of Physical Chemistry II, Ruhr University Bochum, 44780 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr University Bochum, 44780 Bochum, Germany
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4
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Chen C, Henderson JN, Ruchkin DA, Kirsh JM, Baranov MS, Bogdanov AM, Mills JH, Boxer SG, Fang C. Structural Characterization of Fluorescent Proteins Using Tunable Femtosecond Stimulated Raman Spectroscopy. Int J Mol Sci 2023; 24:11991. [PMID: 37569365 PMCID: PMC10418586 DOI: 10.3390/ijms241511991] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
The versatile functions of fluorescent proteins (FPs) as fluorescence biomarkers depend on their intrinsic chromophores interacting with the protein environment. Besides X-ray crystallography, vibrational spectroscopy represents a highly valuable tool for characterizing the chromophore structure and revealing the roles of chromophore-environment interactions. In this work, we aim to benchmark the ground-state vibrational signatures of a series of FPs with emission colors spanning from green, yellow, orange, to red, as well as the solvated model chromophores for some of these FPs, using wavelength-tunable femtosecond stimulated Raman spectroscopy (FSRS) in conjunction with quantum calculations. We systematically analyzed and discussed four factors underlying the vibrational properties of FP chromophores: sidechain structure, conjugation structure, chromophore conformation, and the protein environment. A prominent bond-stretching mode characteristic of the quinoidal resonance structure is found to be conserved in most FPs and model chromophores investigated, which can be used as a vibrational marker to interpret chromophore-environment interactions and structural effects on the electronic properties of the chromophore. The fundamental insights gained for these light-sensing units (e.g., protein active sites) substantiate the unique and powerful capability of wavelength-tunable FSRS in delineating FP chromophore properties with high sensitivity and resolution in solution and protein matrices. The comprehensive characterization for various FPs across a colorful palette could also serve as a solid foundation for future spectroscopic studies and the rational engineering of FPs with diverse and improved functions.
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Affiliation(s)
- Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA;
| | - J. Nathan Henderson
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA; (J.N.H.); (J.H.M.)
| | - Dmitry A. Ruchkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ulitsa Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; (D.A.R.); (M.S.B.); (A.M.B.)
| | - Jacob M. Kirsh
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA; (J.M.K.); (S.G.B.)
| | - Mikhail S. Baranov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ulitsa Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; (D.A.R.); (M.S.B.); (A.M.B.)
- Laboratory of Medicinal Substances Chemistry, Institute of Translational Medicine, Pirogov Russian National Research Medical University, Ostrovitianov 1, 117997 Moscow, Russia
| | - Alexey M. Bogdanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ulitsa Miklukho-Maklaya, 16/10, 117997 Moscow, Russia; (D.A.R.); (M.S.B.); (A.M.B.)
| | - Jeremy H. Mills
- Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA; (J.N.H.); (J.H.M.)
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA; (J.M.K.); (S.G.B.)
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA;
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5
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Chen C, Zhang H, Zhang J, Ai HW, Fang C. Structural origin and rational development of bright red noncanonical variants of green fluorescent protein. Phys Chem Chem Phys 2023; 25:15624-15634. [PMID: 37211909 PMCID: PMC10330862 DOI: 10.1039/d3cp01315d] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The incorporation of noncanonical amino acids (ncAAs) into fluorescent proteins is promising for red-shifting their fluorescence and benefiting tissue imaging with deep penetration and low phototoxicity. However, ncAA-based red fluorescent proteins (RFPs) have been rare. The 3-aminotyrosine modified superfolder green fluorescent protein (aY-sfGFP) represents a recent advance, yet the molecular mechanism for its red-shifted fluorescence remains elusive while its dim fluorescence hinders applications. Herein, we implement femtosecond stimulated Raman spectroscopy to obtain structural fingerprints in the electronic ground state and reveal that aY-sfGFP possesses a GFP-like instead of RFP-like chromophore. Red color of aY-sfGFP intrinsically arises from a unique "double-donor" chromophore structure that raises ground-state energy and enhances charge transfer, notably differing from the conventional conjugation mechanism. We further developed two aY-sfGFP mutants (E222H and T203H) with significantly improved (∼12-fold higher) brightness by rationally restraining the chromophore's nonradiative decay through electronic and steric effects, aided by solvatochromic and fluorogenic studies of the model chromophore in solution. This study thus provides functional mechanisms and generalizable insights into ncAA-RFPs with an efficient route for engineering redder and brighter fluorescent proteins.
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Affiliation(s)
- Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
| | - Hao Zhang
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA.
- Department of Molecular Physiology and Biological Physics and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Jing Zhang
- Department of Molecular Physiology and Biological Physics and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Hui-Wang Ai
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA.
- Department of Molecular Physiology and Biological Physics and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
- The UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
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6
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Xie J, Wang Z, Zhu R, Jiang J, Weng TC, Ren Y, Han S, Huang Y, Liu W. Investigation of Excited-State Intramolecular Proton Transfer and Structural Dynamics in Bis-Benzimidazole Derivative (BBM). Int J Mol Sci 2023; 24:ijms24119438. [PMID: 37298391 DOI: 10.3390/ijms24119438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/19/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
The bis-benzimidazole derivative (BBM) molecule, consisting of two 2-(2'-hydroxyphenyl) benzimidazole (HBI) halves, has been synthesized and successfully utilized as a ratiometric fluorescence sensor for the sensitive detection of Cu2+ based on enol-keto excited-state intramolecular proton transfer (ESIPT). In this study, we strategically implement femtosecond stimulated Raman spectroscopy and several time-resolved electronic spectroscopies, aided by quantum chemical calculations to investigate the detailed primary photodynamics of the BBM molecule. The results demonstrate that the ESIPT from BBM-enol* to BBM-keto* was observed in only one of the HBI halves with a time constant of 300 fs; after that, the rotation of the dihedral angle between the two HBI halves generated a planarized BBM-keto* isomer in 3 ps, leading to a dynamic redshift of BBM-keto* emission.
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Affiliation(s)
- Junhan Xie
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ziyu Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ruixue Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiaming Jiang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tsu-Chien Weng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yi Ren
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Shuhua Han
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
| | - Yifan Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Weimin Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
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7
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Solaris J, Krueger TD, Chen C, Fang C. Photogrammetry of Ultrafast Excited-State Intramolecular Proton Transfer Pathways in the Fungal Pigment Draconin Red. Molecules 2023; 28:molecules28083506. [PMID: 37110741 PMCID: PMC10144053 DOI: 10.3390/molecules28083506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Proton transfer processes of organic molecules are key to charge transport and photoprotection in biological systems. Among them, excited-state intramolecular proton transfer (ESIPT) reactions are characterized by quick and efficient charge transfer within a molecule, resulting in ultrafast proton motions. The ESIPT-facilitated interconversion between two tautomers (PS and PA) comprising the tree fungal pigment Draconin Red in solution was investigated using a combination of targeted femtosecond transient absorption (fs-TA) and excited-state femtosecond stimulated Raman spectroscopy (ES-FSRS) measurements. Transient intensity (population and polarizability) and frequency (structural and cooling) dynamics of -COH rocking and -C=C, -C=O stretching modes following directed stimulation of each tautomer elucidate the excitation-dependent relaxation pathways, particularly the bidirectional ESIPT progression out of the Franck-Condon region to the lower-lying excited state, of the intrinsically heterogeneous chromophore in dichloromethane solvent. A characteristic overall excited-state PS-to-PA transition on the picosecond timescale leads to a unique "W"-shaped excited-state Raman intensity pattern due to dynamic resonance enhancement with the Raman pump-probe pulse pair. The ability to utilize quantum mechanics calculations in conjunction with steady-state electronic absorption and emission spectra to induce disparate excited-state populations in an inhomogeneous mixture of similar tautomers has broad implications for the modeling of potential energy surfaces and delineation of reaction mechanisms in naturally occurring chromophores. Such fundamental insights afforded by in-depth analysis of ultrafast spectroscopic datasets are also beneficial for future development of sustainable materials and optoelectronics.
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Affiliation(s)
- Janak Solaris
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA
| | - Taylor D Krueger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA
| | - Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USA
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8
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Hoberg C, Talbot JJ, Shee J, Ockelmann T, Das Mahanta D, Novelli F, Head-Gordon M, Havenith M. Caught in the act: real-time observation of the solvent response that promotes excited-state proton transfer in pyranine. Chem Sci 2023; 14:4048-4058. [PMID: 37063810 PMCID: PMC10094129 DOI: 10.1039/d2sc07126f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
Photo-induced excited-state proton transfer (ESPT) reactions are of central importance in many biological and chemical processes. Identifying mechanistic details of the solvent reorganizations that facilitate proton transfer however, is challenging for current experimental and theoretical approaches. Using optical pump THz probe (OPTP) spectroscopy and molecular dynamics simulations, we were able to elucidate the ultrafast changes in the solvation environment for three derivatives of pyranine: the photoacid HPTS, the methoxy derivative MPTS, and the photobase OPTS. Experimentally, we find damped oscillations in the THz signal at short times and our simulations enable their assignment to vibrational energy transfer beatings between the photoexcited chromophore and nearby solvent molecules. The simulations of HPTS reveal strikingly efficient sub-ps energy transfer into a particular solvent mode, that is active near 4 THz, and which can provide the requisite energy required for solvent reorganization promoting proton transfer. Similar oscillations are present in the THz signal for all three derivatives, however the signal is damped rapidly for HPTS (within 0.4 ps) and more slowly for MPTS (within 1.4 ps) and OPTS (within 2.0 ps). For HPTS, we also characterize an additional phonon-like propagation of the proton into the bulk with a 140 ps period and an 83 ps damping time. Thermalization of the solvent occurs on a time scale exceeding 120 ps.
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Affiliation(s)
- Claudius Hoberg
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum 44780 Bochum Germany
| | - Justin J Talbot
- Department of Chemistry, University of California Berkeley California 94720 USA
| | - James Shee
- Department of Chemistry, University of California Berkeley California 94720 USA
| | - Thorsten Ockelmann
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum 44780 Bochum Germany
| | - Debasish Das Mahanta
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum 44780 Bochum Germany
| | - Fabio Novelli
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum 44780 Bochum Germany
| | - Martin Head-Gordon
- Department of Chemistry, University of California Berkeley California 94720 USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum 44780 Bochum Germany
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9
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Krueger TD, Tang L, Fang C. Delineating Ultrafast Structural Dynamics of a Green-Red Fluorescent Protein for Calcium Sensing. BIOSENSORS 2023; 13:bios13020218. [PMID: 36831983 PMCID: PMC9954042 DOI: 10.3390/bios13020218] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 05/14/2023]
Abstract
Fluorescent proteins (FPs) are indispensable tools for noninvasive bioimaging and sensing. Measuring the free cellular calcium (Ca2+) concentrations in vivo with genetically encodable FPs can be a relatively direct measure of neuronal activity due to the complex signaling role of these ions. REX-GECO1 is a recently developed red-green emission and excitation ratiometric FP-based biosensor that achieves a high dynamic range due to differences in the chromophore response to light excitation with and without calcium ions. Using steady-state electronic measurements (UV/Visible absorption and emission), along with time-resolved spectroscopic techniques including femtosecond transient absorption (fs-TA) and femtosecond stimulated Raman spectroscopy (FSRS), the potential energy surfaces of these unique biosensors are unveiled with vivid details. The ground-state structural characterization of the Ca2+-free biosensor via FSRS reveals a more spacious protein pocket that allows the chromophore to efficiently twist and reach a dark state. In contrast, the more compressed cavity within the Ca2+-bound biosensor results in a more heterogeneous distribution of chromophore populations that results in multi-step excited state proton transfer (ESPT) pathways on the sub-140 fs, 600 fs, and 3 ps timescales. These results enable rational design strategies to enlarge the spectral separation between the protonated/deprotonated forms and the Stokes shift leading to a larger dynamic range and potentially higher fluorescence quantum yield, which should be broadly applicable to the calcium imaging and biosensor communities.
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Pu R, Wang Z, Zhu R, Jiang J, Weng TC, Huang Y, Liu W. Investigation of Ultrafast Configurational Photoisomerization of Bilirubin Using Femtosecond Stimulated Raman Spectroscopy. J Phys Chem Lett 2023; 14:809-816. [PMID: 36655842 DOI: 10.1021/acs.jpclett.2c03535] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Phototherapy is an efficient and safe way to reduce high levels of free 4Z,15Z-bilirubin (ZZ-BR) in the serum of newborns. The success of BR phototherapy lies in photoinduced configurational and structural isomerization processes that form excretable isomers. However, the physical picture of photoinduced photoisomerization of ZZ-BR is still unclear. Here, we strategically implement tunable femtosecond stimulated Raman spectroscopy and several time-resolved electronic spectroscopies, assisted by quantum chemical calculations, to dissect the detailed primary configurational isomerization dynamics of free ZZ-BR in organic solvents. The results of this study demonstrate that upon photoexcitation, ultrafast configurational isomerization proceeds by a volume-conserving "hula twist", followed by intramolecular hydrogen-bond distortion and large-scale rotation of the two dipyrrinone halves of the ZZ-BR isomer in a few picoseconds. After that, most of the population recovers back to ZZ-BR, and a very small amount is converted into stable BR isomers via structural isomerization.
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Affiliation(s)
- Ruihua Pu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Ziyu Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Ruixue Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jiaming Jiang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tsu-Chien Weng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yifan Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Weimin Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
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11
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Ultrafast Spectroscopies of Nitrophenols and Nitrophenolates in Solution: From Electronic Dynamics and Vibrational Structures to Photochemical and Environmental Implications. Molecules 2023; 28:molecules28020601. [PMID: 36677656 PMCID: PMC9866910 DOI: 10.3390/molecules28020601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/27/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Nitrophenols are a group of small organic molecules with significant environmental implications from the atmosphere to waterways. In this work, we investigate a series of nitrophenols and nitrophenolates, with the contrasting ortho-, meta-, and para-substituted nitro group to the phenolic hydroxy or phenolate oxygen site (2/3/4NP or NP-), implementing a suite of steady-state and time-resolved spectroscopic techniques that include UV/Visible spectroscopy, femtosecond transient absorption (fs-TA) spectroscopy with probe-dependent and global analysis, and femtosecond stimulated Raman spectroscopy (FSRS), aided by quantum calculations. The excitation-dependent (400 and 267 nm) electronic dynamics in water and methanol, for six protonated or deprotonated nitrophenol molecules (three regioisomers in each set), enable a systematic investigation of the excited-state dynamics of these functional "nanomachines" that can undergo nitro-group twisting (as a rotor), excited-state intramolecular or intermolecular proton transfer (donor-acceptor, ESIPT, or ESPT), solvation, and cooling (chromophore) events on molecular timescales. In particular, the meta-substituted compound 3NP or 3NP- exhibits the strongest charge-transfer character with FSRS signatures (e.g., C-N peak frequency), and thus, does not favor nitroaromatic twist in the excited state, while the ortho-substituted compound 2NP can undergo ESIPT in water and likely generate nitrous acid (HONO) after 267 nm excitation. The delineated mechanistic insights into the nitro-substituent-location-, protonation-, solvent-, and excitation-wavelength-dependent effects on nitrophenols, in conjunction with the ultraviolet-light-induced degradation of 2NP in water, substantiates an appealing discovery loop to characterize and engineer functional molecules for environmental applications.
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12
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Krueger TD, Tang L, Chen C, Zhu L, Breen IL, Wachter RM, Fang C. To twist or not to twist: From chromophore structure to dynamics inside engineered photoconvertible and photoswitchable fluorescent proteins. Protein Sci 2023; 32:e4517. [PMID: 36403093 PMCID: PMC9793981 DOI: 10.1002/pro.4517] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/31/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022]
Abstract
Green-to-red photoconvertible fluorescent proteins (FPs) are vital biomimetic tools for powerful techniques such as super-resolution imaging. A unique Kaede-type FP named the least evolved ancestor (LEA) enables delineation of the evolutionary step to acquire photoconversion capability from the ancestral green fluorescent protein (GFP). A key residue, Ala69, was identified through several steady-state and time-resolved spectroscopic techniques that allows LEA to effectively photoswitch and enhance the green-to-red photoconversion. However, the inner workings of this functional protein have remained elusive due to practical challenges of capturing the photoexcited chromophore motions in real time. Here, we implemented femtosecond stimulated Raman spectroscopy and transient absorption on LEA-A69T, aided by relevant crystal structures and control FPs, revealing that Thr69 promotes a stronger π-π stacking interaction between the chromophore phenolate (P-)ring and His193 in FP mutants that cannot photoconvert or photoswitch. Characteristic time constants of ~60-67 ps are attributed to P-ring twist as the onset for photoswitching in LEA (major) and LEA-A69T (minor) with photoconversion capability, different from ~16/29 ps in correlation with the Gln62/His62 side-chain twist in ALL-GFP/ALL-Q62H, indicative of the light-induced conformational relaxation preferences in various local environments. A minor subpopulation of LEA-A69T capable of positive photoswitching was revealed by time-resolved electronic spectroscopies with targeted light irradiation wavelengths. The unveiled chromophore structure and dynamics inside engineered FPs in an aqueous buffer solution can be generalized to improve other green-to-red photoconvertible FPs from the bottom up for deeper biophysics with molecular biology insights and powerful bioimaging advances.
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Affiliation(s)
| | - Longteng Tang
- Department of ChemistryOregon State UniversityCorvallisOregonUSA
| | - Cheng Chen
- Department of ChemistryOregon State UniversityCorvallisOregonUSA
| | - Liangdong Zhu
- Department of ChemistryOregon State UniversityCorvallisOregonUSA
| | - Isabella L. Breen
- School of Molecular Sciences, Center for Bioenergy and Photosynthesis, Biodesign Center for Applied Structural DiscoveryArizona State UniversityTempeArizonaUSA
| | - Rebekka M. Wachter
- School of Molecular Sciences, Center for Bioenergy and Photosynthesis, Biodesign Center for Applied Structural DiscoveryArizona State UniversityTempeArizonaUSA
| | - Chong Fang
- Department of ChemistryOregon State UniversityCorvallisOregonUSA
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13
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Knorr J, Sülzner N, Geissler B, Spies C, Grandjean A, Kutta RJ, Jung G, Nuernberger P. Ultrafast transient absorption and solvation of a super-photoacid in acetoneous environments. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES : OFFICIAL JOURNAL OF THE EUROPEAN PHOTOCHEMISTRY ASSOCIATION AND THE EUROPEAN SOCIETY FOR PHOTOBIOLOGY 2022; 21:2179-2192. [PMID: 36178669 DOI: 10.1007/s43630-022-00287-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/08/2022] [Indexed: 12/13/2022]
Abstract
The phenomenon of photoacidity, i.e., an increase in acidity by several orders of magnitude upon electronic excitation, is frequently encountered in aromatic alcohols capable of transferring a proton to a suitable acceptor. A promising new class of neutral super-photoacids based on pyranine derivatives has been shown to exhibit pronounced solvatochromic effects. To disclose the underlying mechanisms contributing to excited-state proton transfer (ESPT) and the temporal characteristics of solvation and ESPT, we scrutinize the associated ultrafast dynamics of the strongest photoacid of this class, namely tris(1,1,1,3,3,3-hexafluoropropan-2-yl)8-hydroxypyrene-1,3,6-trisulfonate, in acetoneous environment, thereby finding experimental evidence for ESPT even under these adverse conditions for proton transfer. Juxtaposing results from time-correlated single-photon counting and femtosecond transient absorption measurements combined with a complete decomposition of all signal components, i.e., absorption of ground and excited states as well as stimulated emission, we disclose dynamics of solvation, rotational diffusion, and radiative relaxation processes in acetone and identify the relevant steps of ESPT along with the associated time scales.
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Affiliation(s)
- Johannes Knorr
- Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Niklas Sülzner
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780, Bochum, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Bastian Geissler
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Christian Spies
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Alexander Grandjean
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany
| | - Gregor Jung
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany. .,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany.
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14
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Tang L, Bednar RM, Rozanov ND, Hemshorn ML, Mehl RA, Fang C. Rational Design for High Bioorthogonal Fluorogenicity of Tetrazine-Encoded Green Fluorescent Proteins. NATURAL SCIENCES (WEINHEIM, GERMANY) 2022; 2:e20220028. [PMID: 36440454 PMCID: PMC9699285 DOI: 10.1002/ntls.20220028] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The development of bioorthogonal fluorogenic probes constitutes a vital force to advance life sciences. Tetrazine-encoded green fluorescent proteins (GFPs) show high bioorthogonal reaction rate and genetic encodability, but suffer from low fluorogenicity. Here, we unveil the real-time fluorescence mechanisms by investigating two site-specific tetrazine-modified superfolder GFPs via ultrafast spectroscopy and theoretical calculations. Förster resonance energy transfer (FRET) is quantitatively modeled and revealed to govern the fluorescence quenching; for GFP150-Tet with a fluorescence turn-on ratio of ~9, it contains trimodal subpopulations with good (P1), random (P2), and poor (P3) alignments between the transition dipole moments of protein chromophore (donor) and tetrazine tag (Tet-v2.0, acceptor). By rationally designing a more free/tight environment, we created new mutants Y200A/S202Y to introduce more P2/P1 populations and improve the turn-on ratios to ~14/31, making the fluorogenicity of GFP150-Tet-S202Y the highest among all up-to-date tetrazine-encoded GFPs. In live eukaryotic cells, the GFP150-Tet-v3.0-S202Y mutant demonstrates notably increased fluorogenicity, substantiating our generalizable design strategy.
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Affiliation(s)
- Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA
| | - Riley M. Bednar
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural and Life Sciences Building, Corvallis, Oregon 97331-7305, USA
| | - Nikita D. Rozanov
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA
| | - Marcus L. Hemshorn
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural and Life Sciences Building, Corvallis, Oregon 97331-7305, USA
| | - Ryan A. Mehl
- Department of Biochemistry and Biophysics, Oregon State University, 2011 Agricultural and Life Sciences Building, Corvallis, Oregon 97331-7305, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA
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15
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Nandi R, Amdursky N. The Dual Use of the Pyranine (HPTS) Fluorescent Probe: A Ground-State pH Indicator and an Excited-State Proton Transfer Probe. Acc Chem Res 2022; 55:2728-2739. [PMID: 36053265 PMCID: PMC9494743 DOI: 10.1021/acs.accounts.2c00458] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Indexed: 01/19/2023]
Abstract
Molecular fluorescent probes are an essential experimental tool in many fields, ranging from biology to chemistry and materials science, to study the localization and other environmental properties surrounding the fluorescent probe. Thousands of different molecular fluorescent probes can be grouped into different families according to their photophysical properties. This Account focuses on a unique class of fluorescent probes that distinguishes itself from all other probes. This class is termed photoacids, which are molecules exhibiting a change in their acid-base transition between the ground and excited states, resulting in a large change in their pKa values between these two states, which is thermodynamically described using the Förster cycle. While there are many different photoacids, we focus only on pyranine, which is the most used photoacid, with pKa values of ∼7.4 and ∼0.4 for its ground and excited states, respectively. Such a difference between the pKa values is the basis for the dual use of the pyranine fluorescent probe. Furthermore, the protonated and deprotonated states of pyranine absorb and emit at different wavelengths, making it easy to focus on a specific state. Pyranine has been used for decades as a fluorescent pH indicator for physiological pH values, which is based on its acid-base equilibrium in the ground state. While the unique excited-state proton transfer (ESPT) properties of photoacids have been explored for more than a half-century, it is only recently that photoacids and especially pyranine have been used as fluorescent probes for the local environment of the probe, especially the hydration layer surrounding it and related proton diffusion properties. Such use of photoacids is based on their capability for ESPT from the photoacid to a nearby proton acceptor, which is usually, but not necessarily, water. In this Account, we detail the photophysical properties of pyranine, distinguishing between the processes in the ground state and the ones in the excited state. We further review the different utilization of pyranine for probing different properties of the environment. Our main perspective is on the emerging use of the ESPT process for deciphering the hydration layer around the probe and other parameters related to proton diffusion taking place while the molecule is in the excited state, focusing primarily on bio-related materials. Special attention is given to how to perform the experiments and, most importantly, how to interpret their results. We also briefly discuss the breadth of possibilities in making pyranine derivatives and the use of pyranine for controlling dynamic reactions.
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Affiliation(s)
- Ramesh Nandi
- Schulich Faculty of Chemistry, Technion − Israel Institute of Technology, Haifa 3200003, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion − Israel Institute of Technology, Haifa 3200003, Israel
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16
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Boulanger SA, Chen C, Myasnyanko IN, Baranov MS, Fang C. Fluorescence Modulation of ortho-Green Fluorescent Protein Chromophores Following Ultrafast Proton Transfer in Solution. J Phys Chem B 2022; 126:5081-5093. [PMID: 35786966 DOI: 10.1021/acs.jpcb.2c03812] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photophysical and photochemical properties of the green fluorescent protein (GFP) chromophore and derivatives underlie their bioimaging applications. To date, ultrafast spectroscopic tools represent the key for unraveling fluorescence mechanisms toward rational design of this powerful biomimetic framework. To correlate the excited-state intramolecular proton transfer (ESIPT) with chromophore emission properties, we implement experimental and computational tool sets to elucidate real-time electronic and structural dynamics of two archetypal ortho-GFP chromophores (o-HBDI and o-LHBDI) possessing an intramolecular hydrogen bond to undergo efficient ESIPT, only differing in a bridge-bond constraint. Using excited-state femtosecond stimulated Raman spectroscopy (FSRS), a low-frequency phenolic (P)-ring-deformation mode (∼562 cm-1) was uncovered to accompany ESIPT. The tautomerized chromophore undergoes either rapid P-ring isomerization to reach the ground state with essentially no fluorescence for o-HBDI or enhanced (up to an impressive 180-fold in acetonitrile) and solvent-polarity-dependent fluorescence by P-ring locking in o-LHBDI. The significant dependence of the fluorescence enhancement ratio on solvent viscosity confirms P-ring isomerization as the dominant nonradiative decay pathway for o-HBDI. This work provides crucial insights into the dynamic solute-solvent electrostatic and steric interactions, enabling the application-specific improvement of ESIPT-capable molecules as versatile fluorescence-based sensors and imaging agents from large Stokes shift emission to brighter probes in physiological environments.
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Affiliation(s)
- Sean A Boulanger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Ivan N Myasnyanko
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia.,Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia
| | - Mikhail S Baranov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia.,Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
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17
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Tang L, Fang C. Photoswitchable Fluorescent Proteins: Mechanisms on Ultrafast Timescales. Int J Mol Sci 2022; 23:ijms23126459. [PMID: 35742900 PMCID: PMC9223536 DOI: 10.3390/ijms23126459] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 12/15/2022] Open
Abstract
The advancement of super-resolution imaging (SRI) relies on fluorescent proteins with novel photochromic properties. Using light, the reversibly switchable fluorescent proteins (RSFPs) can be converted between bright and dark states for many photocycles and their emergence has inspired the invention of advanced SRI techniques. The general photoswitching mechanism involves the chromophore cis-trans isomerization and proton transfer for negative and positive RSFPs and hydration-dehydration for decoupled RSFPs. However, a detailed understanding of these processes on ultrafast timescales (femtosecond to millisecond) is lacking, which fundamentally hinders the further development of RSFPs. In this review, we summarize the current progress of utilizing various ultrafast electronic and vibrational spectroscopies, and time-resolved crystallography in investigating the on/off photoswitching pathways of RSFPs. We show that significant insights have been gained for some well-studied proteins, but the real-time "action" details regarding the bidirectional cis-trans isomerization, proton transfer, and intermediate states remain unclear for most systems, and many other relevant proteins have not been studied yet. We expect this review to lay the foundation and inspire more ultrafast studies on existing and future engineered RSFPs. The gained mechanistic insights will accelerate the rational development of RSFPs with enhanced two-way switching rate and efficiency, better photostability, higher brightness, and redder emission colors.
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18
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Twisted intramolecular charge transfer of nitroaromatic push-pull chromophores. Sci Rep 2022; 12:6557. [PMID: 35449231 PMCID: PMC9023442 DOI: 10.1038/s41598-022-10565-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/11/2022] [Indexed: 12/02/2022] Open
Abstract
The structural changes during the intramolecular charge transfer (ICT) of nitroaromatic chromophores, 4-dimethylamino-4′-nitrobiphenyl (DNBP) and 4-dimethylamino-4′-nitrostilbene (DNS) were investigated by femtosecond stimulated Raman spectroscopy (FSRS) with both high spectral and temporal resolutions. The kinetically resolved Raman spectra of DNBP and DNS in the locally-excited and charge-transferred states of the S1 state appear distinct, especially in the skeletal vibrational modes of biphenyl and stilbene including ν8a and νC=C. The ν8a of two phenyls and the νC=C of the central ethylene group (only for stilbene), which are strongly coupled in the planar geometries, are broken with the twist of nitrophenyl group with the ICT. Time-resolved vibrational spectroscopy measurements and the time-dependent density functional theory simulations support the ultrafast ICT dynamics of 220–480 fs with the twist of nitrophenyl group occurring in the S1 state of the nitroaromatic chromophores. While the ICT of DNBP occurs via a barrier-less pathway, the ICT coordinates of DNS are strongly coupled to several low-frequency out-of-phase deformation modes relevant to the twist of the nitrophenyl group.
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19
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Kim KI, Tang L, Muratli JM, Fang C, Ji X. A Graphite∥PTCDI Aqueous Dual-Ion Battery. CHEMSUSCHEM 2022; 15:e202102394. [PMID: 35132831 DOI: 10.1002/cssc.202102394] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/05/2021] [Indexed: 06/14/2023]
Abstract
A full cell chemistry of aqueous dual-ion battery (DIB) was reported, comprising the graphite cathode and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) as the anode. This DIB employed a mixture aqueous electrolyte: 5 m tributylmethylammonium (TBMA) chloride plus 5 m MgCl2 , where [MgCl3 ]- and TBMA+ serve as the charge carriers for cathode and anode of the DIB, respectively. This novel full cell exhibited a specific capacity of around 41 mAh g-1 based on the total active mass of both electrodes with an average operation voltage of 1.45 V and stable cycling for 400 cycles.
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Affiliation(s)
- Keun-Il Kim
- Department of Chemistry, Oregon State University, Corvallis, Oregon, 97331-4003, United States
| | - Longteng Tang
- Department of Chemistry, Oregon State University, Corvallis, Oregon, 97331-4003, United States
| | - Jesse M Muratli
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503, United States
| | - Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, Oregon, 97331-4003, United States
| | - Xiulei Ji
- Department of Chemistry, Oregon State University, Corvallis, Oregon, 97331-4003, United States
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20
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Intramolecular Charge Transfer of Curcumin and Solvation Dynamics of DMSO Probed by Time-Resolved Raman Spectroscopy. Int J Mol Sci 2022; 23:ijms23031727. [PMID: 35163647 PMCID: PMC8835799 DOI: 10.3390/ijms23031727] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 02/04/2023] Open
Abstract
Intramolecular charge transfer (ICT) of curcumin in dimethyl sulfoxide (DMSO) solution in the excited state was investigated by femtosecond electronic and vibrational spectroscopy. Excited-state Raman spectra of curcumin in the locally-excited and charge-transferred (CT) state of the S1 excited state were separated due to high temporal (<50 fs) and spectral (<10 cm−1) resolutions of femtosecond stimulated Raman spectroscopy. The ultrafast (0.6–0.8 ps) ICT and subsequent vibrational relaxation (6–9 ps) in the CT state were ubiquitously observed in the ground- and excited-state vibrational modes of the solute curcumin and the νCSC and νS=O modes of solvent DMSO. The ICT of curcumin in the excited state was preceded by the disruption of the solvation shells, including the breakage of hydrogen bonding between curcumin and DMSO molecules, which occurs at the ultrafast (20–50 fs) time scales.
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21
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Tang L, Fang C. Fluorescence Modulation by Ultrafast Chromophore Twisting Events: Developing a Powerful Toolset for Fluorescent-Protein-Based Imaging. J Phys Chem B 2021; 125:13610-13623. [PMID: 34883016 DOI: 10.1021/acs.jpcb.1c08570] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The advancement of modern life sciences has benefited tremendously from the discovery and development of fluorescent proteins (FPs), widely expressed in live cells to track a myriad of cellular events. The chromophores of various FPs can undergo many ultrafast photophysical and/or photochemical processes in the electronic excited state and emit fluorescence with different colors. However, the chromophore becomes essentially nonfluorescent in solution environment due to its intrinsic twisting capability upon photoexcitation. To study "microscopic" torsional events and their effects on "macroscopic" fluorescence, we have developed an integrated ultrafast characterization platform involving femtosecond transient absorption (fs-TA) and wavelength-tunable femtosecond stimulated Raman spectroscopy (FSRS). A wide range of naturally occurring, circularly permuted, non-canonical amino-acid-decorated FPs and FP-based optical highlighters with photochromicity, photoconversion, and/or photoswitching capabilities have been recently investigated in great detail. Twisting conformational motions were elucidated to exist in all of these systems but to various extents. The associated different ultrafast pathways can be monitored via frequency changes of characteristic Raman bands during primary events and functional processes. The mapped electronic and structural dynamics information is crucial and has shown great potential and initial success for the rational design of proteins and other photoreceptors with novel functions and fluorescence properties.
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Affiliation(s)
- Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, United States
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, United States
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22
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Krueger TD, Fang C. Elucidating Inner Workings of Naturally Sourced Organic Optoelectronic Materials with Ultrafast Spectroscopy. Chemistry 2021; 27:17736-17750. [PMID: 34545971 DOI: 10.1002/chem.202102766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Indexed: 01/18/2023]
Abstract
Recent advances in sustainable optoelectronics including photovoltaics, light-emitting diodes, transistors, and semiconductors have been enabled by π-conjugated organic molecules. A fundamental understanding of light-matter interactions involving these materials can be realized by time-resolved electronic and vibrational spectroscopies. In this Minireview, the photoinduced mechanisms including charge/energy transfer, electronic (de)localization, and excited-state proton transfer are correlated with functional properties encompassing optical absorption, fluorescence quantum yield, conductivity, and photostability. Four naturally derived molecules (xylindein, dimethylxylindein, alizarin, indigo) with ultrafast spectral insights showcase efficient energy dissipation involving H-bonding networks and proton motions, which yield high photostability. Rational design principles derived from such investigations could increase the efficiency for light harvesting, triplet formation, and photosensitivity for improved and versatile optoelectronic performance.
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Affiliation(s)
- Taylor D Krueger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
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23
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Boulanger SA, Chen C, Myasnyanko IN, Sokolov AI, Baranov MS, Fang C. Excited-State Dynamics of a meta-Dimethylamino Locked GFP Chromophore as a Fluorescence Turn-on Water Sensor †. Photochem Photobiol 2021; 98:311-324. [PMID: 34714942 DOI: 10.1111/php.13552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 12/14/2022]
Abstract
Strategic incorporation of a meta-dimethylamino (-NMe2 ) group on the conformationally locked green fluorescent protein (GFP) model chromophore (m-NMe2 -LpHBDI) has drastically altered molecular electronic properties, counterintuitively enhancing fluorescence of only the neutral and cationic chromophores in aqueous solution. A ˜200-fold decrease in fluorescence quantum yield of m-NMe2 -LpHBDI in alcohols (e.g., MeOH, EtOH and 2-PrOH) supports this GFP-derived compound as a fluorescence turn-on water sensor, with large fluorescence intensity differences between H2 O and ROH emissions in various H2 O/ROH binary mixtures. A combination of steady-state electronic spectroscopy, femtosecond transient absorption, ground-state femtosecond stimulated Raman spectroscopy (FSRS) and quantum calculations elucidates an intermolecular hydrogen-bonding chain between a solvent -OH group and the chromophore phenolic ring -NMe2 and -OH functional groups, wherein fluorescence differences arise from an extended hydrogen-bonding network beyond the first solvation shell, as opposed to fluorescence quenching via a dark twisted intramolecular charge-transfer state. The absence of a meta-NMe2 group twisting coordinate upon electronic excitation was corroborated by experiments on control samples without the meta-NMe2 group or with both meta-NMe2 and para-OH groups locked in a six-membered ring. These deep mechanistic insights stemming from GFP chromophore scaffold will enable rational design of organic, compact and environmentally friendly water sensors.
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Affiliation(s)
| | - Cheng Chen
- Department of Chemistry, Oregon State University, Corvallis, OR
| | - Ivan N Myasnyanko
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia
| | - Anatolii I Sokolov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia
| | - Mikhail S Baranov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia
| | - Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, OR
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24
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Picconi D. Nonadiabatic quantum dynamics of the coherent excited state intramolecular proton transfer of 10-hydroxybenzo[h]quinoline. Photochem Photobiol Sci 2021; 20:1455-1473. [PMID: 34657277 DOI: 10.1007/s43630-021-00112-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/04/2021] [Indexed: 12/13/2022]
Abstract
The photoinduced nonadiabatic dynamics of the enol-keto isomerization of 10-hydroxybenzo[h]quinoline (HBQ) are studied computationally using high-dimensional quantum dynamics. The simulations are based on a diabatic vibronic coupling Hamiltonian, which includes the two lowest [Formula: see text] excited states and a [Formula: see text] state, which has high energy in the Franck-Condon zone, but significantly stabilizes upon excited state intramolecular proton transfer. A procedure, applicable to large classes of excited state proton transfer reactions, is presented to parametrize this model using potential energies, forces and force constants, which, in this case, are obtained by time-dependent density functional theory. The wave packet calculations predict a time scale of 10-15 fs for the photoreaction, and reproduce the time constants and the coherent oscillations observed in time-resolved spectroscopic studies performed on HBQ. In contrast to the interpretation given to the most recent experiments, it is found that the reaction initiated by [Formula: see text] photoexcitation proceeds essentially on a single potential energy surface, and the observed coherences bear signatures of Duschinsky mode-mixing along the reaction path. The dynamics after the [Formula: see text] excitation are instead nonadiabatic, and the [Formula: see text] state plays a major role in the relaxation process. The simulations suggest a mainly active role of the proton in the isomerization, rather than a passive migration assisted by the vibrations of the benzoquinoline backbone.
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Affiliation(s)
- David Picconi
- Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany.
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25
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Xu W, Wei L, Wang Z, Zhu R, Jiang J, Liu H, Du J, Weng TC, Zhang YB, Huang Y, Liu W. Tracking Ultrafast Fluorescence Switch-On and Color-Tuned Dynamics in Acceptor-Donor-Acceptor Chromophore. J Phys Chem B 2021; 125:10796-10804. [PMID: 34524821 DOI: 10.1021/acs.jpcb.1c05936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding how the conformational change of conjugated molecules with acceptor-donor-acceptor (A-D-A) architecture affects their physical and optoelectronic properties is critical for determining their ultimate performance in organic electronic devices. Here, we utilized femtosecond transient absorption, time-resolved upconversion photoluminescence spectroscopy, and tunable femtosecond-stimulated Raman spectroscopy, aided by quantum chemical calculations, to systematically investigate the excited state structural dynamics of the intramolecular charge transfer of the tetramethoxy anthracene-based fluorophore 2,3,6,7-tetramethoxy 9,10-dibenzaldehydeanthracene (AnDA) and its derivative 2,3,6,7-tetramethoxy 9,10-diphenylanthracene (TMDPAn) in chloroform. In the AnDA molecule, the tetramethoxy anthracene and benzaldehyde moieties exhibit a strong ability to donate and withdraw electrons. Upon photoexcitation, AnDA shows intriguing ultrafast fluorescence switch-on and red shift dynamics on charge transfer states, and the temporal evolution of AnDA recorded by ultrafast spectroscopy reveals a dynamic picture of two-step intramolecular charge transfer assisted by ultrafast conformational changes and solvation processes. Removing the aldehyde group from TMDPAn significantly decreases the electron pulling capacity of the phenyl unit and disables charge transfer characteristics.
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Affiliation(s)
- Wenqi Xu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.,STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, People's Republic of China
| | - Lei Wei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Zhengxin Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.,STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, People's Republic of China
| | - Ruixue Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Jiaming Jiang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Huiyan Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Juan Du
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Tsu-Chien Weng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Yue-Biao Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Yifan Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Weimin Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China.,STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, People's Republic of China
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26
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Chiariello MG, Donati G, Raucci U, Perrella F, Rega N. Structural Origin and Vibrational Fingerprints of the Ultrafast Excited State Proton Transfer of the Pyranine-Acetate Complex in Aqueous Solution. J Phys Chem B 2021; 125:10273-10281. [PMID: 34472354 DOI: 10.1021/acs.jpcb.1c05590] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The excited state proton transfer (ESPT) reaction from the photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS or pyranine) to an acetate molecule has been investigated in explicit aqueous solution via excited state ab initio molecular dynamics simulations based on hybrid quantum/molecular mechanics (QM/MM) potentials. In all the trajectories, the direct proton transfer has been observed in the excited state within 1 ps. We find that the initial structural configuration extracted from the ground state distribution strongly affects the ESPT kinetics. Indeed, the relative orientation of the proton donor-acceptor pair and the presence of a water molecule hydrogen bonded to the phenolic acid group of the pyranine are the key factors to facilitate the ESPT. Furthermore, we analyze the vibrational fingerprints of the ESPT reaction, reproducing the blue shift of the acetate CO stretching (COac), from 1666 to 1763 cm-1 testifying the transformation of acetate to acetic acid. Finally, our findings suggest that the acetate CC stretching (CCac) is also sensitive to the progress of the ESPT reaction. The CCac stretching is indeed ruled by the two vibrational modes (928 and 1426 cm-1), that in the excited state are alternately activated when the proton is shared or bound to the donor/acceptor, respectively.
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Affiliation(s)
- Maria Gabriella Chiariello
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Greta Donati
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Umberto Raucci
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Fulvio Perrella
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Nadia Rega
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy.,CRIB Center for Advanced Biomaterials for Healthcare, Piazzale Tecchio, 80-80125 Napoli, Italy
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27
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A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer. CHEMOSENSORS 2021. [DOI: 10.3390/chemosensors9080234] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We discovered a novel fluorophore by incorporating a dimethylamino group (–NMe2) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an environment-polarity sensor in vitro and in vivo. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy in combination with quantum calculations revealed the presence of a twisted intramolecular charge transfer (TICT) state, which is formed by rotation of the –NMe2 group in the electronic excited state. In contrast to the bright fluorescent state (FS), the TICT state is dark and effectively quenches fluorescence upon formation. We employed a newly developed multivariable analysis approach to the FS lifetime in various solvents and showed that the FS → TICT reaction barrier is mainly modulated by H-bonding capability instead of viscosity of the solvent, accounting for the observed polarity dependence. These deep mechanistic insights are further corroborated by the dramatic loss of fluorogenicity for two similar GFP-derived chromophores in which the rotation of the –NMe2 group is inhibited by structural locking.
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28
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Boulanger SA, Chen C, Tang L, Zhu L, Baleeva NS, Myasnyanko IN, Baranov MS, Fang C. Shedding light on ultrafast ring-twisting pathways of halogenated GFP chromophores from the excited to ground state. Phys Chem Chem Phys 2021; 23:14636-14648. [PMID: 34212170 DOI: 10.1039/d1cp02140k] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Since green fluorescent protein (GFP) has revolutionized molecular and cellular biology for about three decades, there has been a keen interest in understanding, designing, and controlling the fluorescence properties of GFP chromophore (i.e., HBDI) derivatives from the protein matrix to solution. Amongst these cross-disciplinary efforts, the elucidation of excited-state dynamics of HBDI derivatives holds the key to correlating the light-induced processes and fluorescence quantum yield (FQY). Herein, we implement steady-state electronic spectroscopy, femtosecond transient absorption (fs-TA), femtosecond stimulated Raman spectroscopy (FSRS), and quantum calculations to study a series of mono- and dihalogenated HBDI derivatives (X = F, Cl, Br, 2F, 2Cl, and 2Br) in basic aqueous solution, gaining new insights into the photophysical reaction coordinates. In the excited state, the halogenated "floppy" chromophores exhibit an anti-heavy atom effect, reflected by strong correlations between FQY vs. Franck-Condon energy (EFC) or Stokes shift, and knrvs. EFC, as well as a swift bifurcation into the I-ring (major) and P-ring (minor) twisting motions. In the ground state, both ring-twisting motions become more susceptible to sterics and exhibit spectral signatures from the halogen-dependent hot ground-state absorption band decay in TA data. We envision this type of systematic analysis of the halogenated HBDI derivatives to provide guiding principles for the site-specific modification of GFP chromophores, and expand design space for brighter and potentially photoswitchable organic chemical probes in aqueous solution with discernible spectral signatures throughout the photocycle.
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Affiliation(s)
- Sean A Boulanger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA.
| | - Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA.
| | - Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA.
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA.
| | - Nadezhda S Baleeva
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia and Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia
| | - Ivan N Myasnyanko
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia and Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia
| | - Mikhail S Baranov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia and Pirogov Russian National Research Medical University, Ostrovitianov 1, Moscow 117997, Russia
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, USA.
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29
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Wei J, Wu Y, Pu R, Shi L, Jiang J, Du J, Guo Z, Huang Y, Liu W. Tracking Ultrafast Structural Dynamics in a Dual-Emission Anti-Kasha-Active Fluorophore Using Femtosecond Stimulated Raman Spectroscopy. J Phys Chem Lett 2021; 12:4466-4473. [PMID: 33955767 DOI: 10.1021/acs.jpclett.1c00202] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The anti-Kasha process provides the possibility of using high-energy excited states to develop novel applications. Our previous research (Nature communications, 2020, 11, 793) has demonstrated a dual-emission anti-Kasha-active fluorophore for bioimaging application, which exhibits near-infrared emissions from the S1 state and visible anti-Kasha emissions from the S2 state. Here, we applied tunable blue-side femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption spectroscopy, assisted by quantum calculations, to reveal the anti-Kasha dual emission mechanism, in which the emergence of two fluorescing states is due to the retardation of internal conversion from the S2 state to the S1 state. It has been demonstrated that the facts of anti-Kasha high-energy emission are commonly attributed to a large energy gap between the two excited states, leading to a decrease in the internal conversion rate due to a poor Franck-Condon factor. In this study, analysis of the calculation and FSRS experimental results provide us further insight into the dual-emission anti-Kasha mechanism, where the observation of hydrogen out-of-plane Raman modes from FSRS suggested that, in addition to the energy-gap law, the initial photoinduced molecular conformational change plays a key role in influencing the rate of internal conversion.
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Affiliation(s)
- Jingle Wei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Yuexia Wu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Ruihua Pu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
| | - Limin Shi
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jiaming Jiang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Juan Du
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Zhiqian Guo
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yifan Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Weimin Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- STU and SIOM Joint Laboratory for Superintense Lasers and the Applications, Shanghai 201210, China
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30
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Chiariello MG, Raucci U, Donati G, Rega N. Water-Mediated Excited State Proton Transfer of Pyranine-Acetate in Aqueous Solution: Vibrational Fingerprints from Ab Initio Molecular Dynamics. J Phys Chem A 2021; 125:3569-3578. [PMID: 33900071 PMCID: PMC8279639 DOI: 10.1021/acs.jpca.1c00692] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
In this work, we
simulate the excited state proton transfer (ESPT)
reaction involving the pyranine photoacid and an acetate molecule
as proton acceptor, connected by a bridge water molecule. We employ
ab initio molecular dynamics combined with an hybrid quantum/molecular
mechanics (QM/MM) framework. Furthermore, a time-resolved vibrational
analysis based on the wavelet-transform allows one to identify two
low frequency vibrational modes that are fingerprints of the ESPT
event: a ring wagging and ring breathing. Their composition suggests
their key role in optimizing the structure of the proton donor–acceptor
couple and promoting the ESPT event. We find that the choice of the
QM/MM partition dramatically affects the photoinduced reactivity of
the system. The QM subspace was gradually extended including the water
molecules directly interacting with the pyranine–water–acetate
system. Indeed, the ESPT reaction takes place when the hydrogen bond
network around the reactive system is taken into account at full QM
level.
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Affiliation(s)
- Maria Gabriella Chiariello
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Umberto Raucci
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Greta Donati
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Nadia Rega
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M.S. Angelo, via Cintia, I-80126 Napoli, Italy.,Centro Interdipartimentale di Ricerca sui Biomateriali (CRIB) Piazzale Tecchio, Largo Barsanti e Matteucci, I-80125 Napoli, Italy
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31
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Tachibana SR, Tang L, Chen C, Zhu L, Takeda Y, Fushimi K, Seevers TK, Narikawa R, Sato M, Fang C. Transient electronic and vibrational signatures during reversible photoswitching of a cyanobacteriochrome photoreceptor. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 250:119379. [PMID: 33401182 DOI: 10.1016/j.saa.2020.119379] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/12/2020] [Accepted: 12/19/2020] [Indexed: 06/12/2023]
Abstract
Cyanobacteriochromes (CBCRs) are an emerging class of photoreceptors that are distant relatives of the phytochromes family. Unlike phytochromes, CBCRs have gained popularity in optogenetics due to their highly diverse spectral properties spanning the UV to near-IR region and only needing a single compact binding domain. AnPixJg2 is a CBCR that can reversibly photoswitch between its red-absorbing (15ZPr) and green-absorbing (15EPg) forms of the phycocyanobilin (PCB) cofactor. To reveal primary events of photoconversion, we implemented femtosecond transient absorption spectroscopy with a homemade LED box and a miniature peristaltic pump flow cell to track transient electronic responses of the photoexcited AnPixJg2 on molecular time scales. The 525 nm laser-induced Pg-to-Pr reverse conversion exhibits a ~3 ps excited-state lifetime before reaching the conical intersection (CI) and undergoing further relaxation on the 30 ps time scale to generate a long-lived Lumi-G ground state intermediate en route to Pr. The 650 nm laser-induced Pr-to-Pg forward conversion is less efficient than reverse conversion, showing a longer-lived excited state which requires two steps with ~13 and 217 ps time constants to enter the CI region. Furthermore, using a tunable ps Raman pump with broadband Raman probe on both the Stokes and anti-Stokes sides, we collected the pre-resonance ground-state femtosecond stimulated Raman spectroscopy (GS-FSRS) data with mode assignments aided by quantum calculations. Key vibrational marker bands at ~850, 1050, 1615, and 1649 cm-1 of the Pr conformer exhibit a notable blueshift to those of the Pg conformer inside AnPixJg2, reflecting the PCB chromophore terminal D (major) and A (minor) ring twist along the primary photoswitching reaction coordinate. This integrated ultrafast spectroscopy and computational platform has the potential to elucidate photochemistry and photophysics of more CBCRs and photoactive proteins in general, providing the highly desirable mechanistic insights to facilitate the rational design of functional molecular sensors and devices.
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Affiliation(s)
- Sean R Tachibana
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States
| | - Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States
| | - Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States
| | - Yuka Takeda
- Graduate School of Integrated Science and Technology, Shizuoka University, 422-8529 Shizuoka, Japan
| | - Keiji Fushimi
- Graduate School of Integrated Science and Technology, Shizuoka University, 422-8529 Shizuoka, Japan
| | - Travis K Seevers
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States
| | - Rei Narikawa
- Graduate School of Integrated Science and Technology, Shizuoka University, 422-8529 Shizuoka, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 332-0012 Saitama, Japan
| | - Moritoshi Sato
- Graduate School of Arts and Sciences, University of Tokyo, 153-8902 Tokyo, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 332-0012 Saitama, Japan
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, United States.
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32
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Krueger TD, Giesbers G, Van Court RC, Zhu L, Kim R, Beaudry CM, Robinson SC, Ostroverkhova O, Fang C. Ultrafast Dynamics and Photoresponse of a Fungi-Derived Pigment Xylindein from Solution to Thin Films. Chemistry 2021; 27:5627-5631. [PMID: 33543812 DOI: 10.1021/acs.jpcc.0c09627] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/05/2021] [Indexed: 05/22/2023]
Abstract
Organic semiconductor materials have recently gained momentum due to their non-toxicity, low cost, and sustainability. Xylindein is a remarkably photostable pigment secreted by fungi that grow on decaying wood, and its relatively strong electronic performance is enabled by π-π stacking and hydrogen-bonding network that promote charge transport. Herein, femtosecond transient absorption spectroscopy with a near-IR probe was used to unveil a rapid excited-state intramolecular proton transfer reaction. Conformational motions potentially lead to a conical intersection that quenches fluorescence in the monomeric state. In concentrated solutions, nascent aggregates exhibit a faster excited state lifetime due to excimer formation, confirmed by the excimer→charge-transfer excited-state absorption band of the xylindein thin film, thus limiting its optoelectronic performance. Therefore, extending the xylindein sidechains with branched alkyl groups may hinder the excimer formation and improve optoelectronic properties of naturally derived materials.
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Affiliation(s)
- Taylor D Krueger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
| | - Gregory Giesbers
- Department of Physics, Oregon State University, 301 Weniger Hall, Corvallis, OR, 97331-6507, USA
| | - Ray C Van Court
- Department of Wood Science and Engineering, Oregon State University, 119 Richardson Hall, Corvallis, OR, 97331-5704, USA
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
| | - Ryan Kim
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
| | - Christopher M Beaudry
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
| | - Seri C Robinson
- Department of Wood Science and Engineering, Oregon State University, 119 Richardson Hall, Corvallis, OR, 97331-5704, USA
| | - Oksana Ostroverkhova
- Department of Physics, Oregon State University, 301 Weniger Hall, Corvallis, OR, 97331-6507, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331-4003, USA
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33
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Tang L, Zhang S, Zhao Y, Rozanov ND, Zhu L, Wu J, Campbell RE, Fang C. Switching between Ultrafast Pathways Enables a Green-Red Emission Ratiometric Fluorescent-Protein-Based Ca 2+ Biosensor. Int J Mol Sci 2021; 22:E445. [PMID: 33466257 PMCID: PMC7794744 DOI: 10.3390/ijms22010445] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 01/25/2023] Open
Abstract
Ratiometric indicators with long emission wavelengths are highly preferred in modern bioimaging and life sciences. Herein, we elucidated the working mechanism of a standalone red fluorescent protein (FP)-based Ca2+ biosensor, REX-GECO1, using a series of spectroscopic and computational methods. Upon 480 nm photoexcitation, the Ca2+-free biosensor chromophore becomes trapped in an excited dark state. Binding with Ca2+ switches the route to ultrafast excited-state proton transfer through a short hydrogen bond to an adjacent Glu80 residue, which is key for the biosensor's functionality. Inspired by the 2D-fluorescence map, REX-GECO1 for Ca2+ imaging in the ionomycin-treated human HeLa cells was achieved for the first time with a red/green emission ratio change (ΔR/R0) of ~300%, outperforming many FRET- and single FP-based indicators. These spectroscopy-driven discoveries enable targeted design for the next-generation biosensors with larger dynamic range and longer emission wavelengths.
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Affiliation(s)
- Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA; (L.T.); (N.D.R.); (L.Z.)
| | - Shuce Zhang
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (S.Z.); (Y.Z.); (J.W.); or
| | - Yufeng Zhao
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (S.Z.); (Y.Z.); (J.W.); or
| | - Nikita D. Rozanov
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA; (L.T.); (N.D.R.); (L.Z.)
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA; (L.T.); (N.D.R.); (L.Z.)
| | - Jiahui Wu
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (S.Z.); (Y.Z.); (J.W.); or
| | - Robert E. Campbell
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (S.Z.); (Y.Z.); (J.W.); or
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA; (L.T.); (N.D.R.); (L.Z.)
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34
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Nag P, Vennapusa SR. Role of Skeletal and O-H Vibrational Motions in the Ultrafast Excited-State Relaxation Dynamics of Alizarin. J Phys Chem A 2020; 124:10989-10996. [PMID: 33331785 DOI: 10.1021/acs.jpca.0c09454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The role of two skeletal (C═C and C═O stretch) and O-H vibrational motions in the internal conversion dynamics associated with the coupled S1(ππ*, A') -S2(nπ*, A″) potential energy surfaces of alizarin are investigated theoretically. Quantum wavepacket dynamics simulations reveal a nonadiabatic population transfer from the "bright" S1(ππ*, A') to "dark" S2(nπ*, A″) state on a time scale of 10 fs. A detailed analysis of computed structural parameters, energetics, and time-dependent observables suggest that these vibrations promote the nonadiabatic dynamics before initiating the proton transfer process. We also discuss how the simultaneous evolution of multidimensional dynamics involving several vibrational degrees of freedom would increase the complexity, while analyzing the spectral and kinetic data of time-resolved spectroscopy measurements.
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Affiliation(s)
- Probal Nag
- Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram, Kerala 695551, India
| | - Sivaranjana Reddy Vennapusa
- Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram, Kerala 695551, India
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35
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Hong MJ, Zhu L, Chen C, Tang L, Lin YH, Li W, Johnson R, Chattopadhyay S, Snaith HJ, Fang C, Labram JG. Time-Resolved Changes in Dielectric Constant of Metal Halide Perovskites under Illumination. J Am Chem Soc 2020; 142:19799-19803. [PMID: 33186029 DOI: 10.1021/jacs.0c07307] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Despite their impressive performance as a solar absorber, much remains unknown on the fundamental properties of metal halide perovskites (MHPs). Their polar nature in particular is an intense area of study, and the relative permittivity (εr) is a parameter widely used to quantify polarization over a range of different time scales. In this report, we have exploited frequency-dependent time-resolved microwave conductivity (TRMC) to study how εr values of a range of MHPs change as a function of time, upon optical illumination. Further characterization of charge carriers and polarizability are conducted by femtosecond transient absorption and stimulated Raman spectroscopy. We find that changes in εr are roughly proportional to photogenerated carrier density but decay with a shorter time constant than conductance, suggesting that the presence of charge carriers alone does not determine polarization.
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Affiliation(s)
- Min Ji Hong
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331, United States
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Cheng Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Longteng Tang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - Yen-Hung Lin
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Wen Li
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.,Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, Xi'an 710072, China
| | - Rose Johnson
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States
| | - Shirsopratim Chattopadhyay
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331, United States
| | - Henry J Snaith
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - John G Labram
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331, United States
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36
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Lee C, Chung S, Song H, Rhee YM, Lee E, Joo T. Excited State Proton Transfer of Quinone Cyanine 9: Implications on the Origin of Super‐Photoacidity. CHEMPHOTOCHEM 2020. [DOI: 10.1002/cptc.202000254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Changmin Lee
- Department of Chemistry Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
| | - Seyoung Chung
- Department of Chemistry Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
| | - Hayoung Song
- Department of Chemistry Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
| | - Young Min Rhee
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Eunsung Lee
- Department of Chemistry Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
| | - Taiha Joo
- Department of Chemistry Pohang University of Science and Technology (POSTECH) Pohang 37673 Republic of Korea
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37
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Twisted Intramolecular Charge Transfer State of a "Push-Pull" Emitter. Int J Mol Sci 2020; 21:ijms21217999. [PMID: 33121185 PMCID: PMC7662227 DOI: 10.3390/ijms21217999] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 10/26/2020] [Accepted: 10/26/2020] [Indexed: 11/17/2022] Open
Abstract
The excited state Raman spectra of 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) in the locally-excited (LE) and the intramolecular charge transfer (ICT) states have been separately measured by time-resolved stimulated Raman spectroscopy. In a polar dimethylsulfoxide solution, the ultrafast ICT of DCM with a time constant of 1.0 ps was observed in addition to the vibrational relaxation in the ICT state of 4–7 ps. On the other hand, the energy of the ICT state of DCM becomes higher than that of the LE state in a less polar chloroform solution, where the initially-photoexcited ICT state with the LE state shows the ultrafast internal conversion to the LE state with a time constant of 300 fs. The excited-state Raman spectra of the LE and ICT state of DCM showed several major vibrational modes of DCM in the LE and ICT conformer states coexisting in the excited state. Comparing to the time-dependent density functional theory simulations and the experimental results of similar push-pull type molecules, a twisted geometry of the dimethylamino group is suggested for the structure of DCM in the S1/ICT state.
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38
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Chiariello MG, Donati G, Rega N. Time-Resolved Vibrational Analysis of Excited State Ab Initio Molecular Dynamics to Understand Photorelaxation: The Case of the Pyranine Photoacid in Aqueous Solution. J Chem Theory Comput 2020; 16:6007-6013. [PMID: 32955870 PMCID: PMC8011922 DOI: 10.1021/acs.jctc.0c00810] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
![]()
We
present a novel time-resolved vibrational analysis for studying
photoinduced nuclear relaxation. Generalized modes velocities are
defined from ab initio molecular dynamics and wavelet transformed,
providing the time localization of vibrational signals in the electronic
excited state. The photoexcited pyranine in aqueous solution is presented
as a case study. The transient and sequential activation of the simulated
vibrational signals is in good agreement with vibrational dynamics
obtained from femtosecond stimulated Raman spectroscopy data.
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Affiliation(s)
- Maria Gabriella Chiariello
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M. S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Greta Donati
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M. S. Angelo, via Cintia, I-80126 Napoli, Italy
| | - Nadia Rega
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario di M. S. Angelo, via Cintia, I-80126 Napoli, Italy.,CRIB Center for Advanced Biomaterials for Healthcare, Largo Barsanti e Matteucci, I-80125 Napoli, Italy
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39
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Verma P, Rosspeintner A, Dereka B, Vauthey E, Kumpulainen T. Broadband fluorescence reveals mechanistic differences in excited-state proton transfer to protic and aprotic solvents. Chem Sci 2020; 11:7963-7971. [PMID: 34094165 PMCID: PMC8163259 DOI: 10.1039/d0sc03316b] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Excited-state proton transfer (ESPT) to solvent is often explained according to the two-step Eigen-Weller model including a contact ion pair (CIP*) as an intermediate, but general applicability of the model has not been thoroughly examined. Furthermore, examples of the spectral identification of CIP* are scarce. Here, we report on a detailed investigation of ESPT to protic (H2O, D2O, MeOH and EtOH) and aprotic (DMSO) solvents utilizing a broadband fluorescence technique with sub-200 fs time resolution. The time-resolved spectra are decomposed into contributions from the protonated and deprotonated species and a clear signature of CIP* is identified in DMSO and MeOH. Interestingly, the CIP* intermediate is not observable in aqueous environment although the dynamics in all solvents are multi-exponential. Global analysis based on the Eigen-Weller model is satisfactory in all solvents, but the marked mechanistic differences between aqueous and organic solvents cast doubt on the physical validity of the rate constants obtained.
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Affiliation(s)
- Pragya Verma
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 65 18 +41 22 379 36 58
| | - Arnulf Rosspeintner
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 65 18 +41 22 379 36 58
| | - Bogdan Dereka
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 65 18 +41 22 379 36 58
| | - Eric Vauthey
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 65 18 +41 22 379 36 58
| | - Tatu Kumpulainen
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 65 18 +41 22 379 36 58
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40
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Oscar BG, Zhu L, Wolfendeen H, Rozanov ND, Chang A, Stout KT, Sandwisch JW, Porter JJ, Mehl RA, Fang C. Dissecting Optical Response and Molecular Structure of Fluorescent Proteins With Non-canonical Chromophores. Front Mol Biosci 2020; 7:131. [PMID: 32733917 PMCID: PMC7358599 DOI: 10.3389/fmolb.2020.00131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 06/02/2020] [Indexed: 12/21/2022] Open
Abstract
Tracking the structural dynamics of fluorescent protein chromophores holds the key to unlocking the fluorescence mechanisms in real time and enabling rational design principles of these powerful and versatile bioimaging probes. By combining recent chemical biology and ultrafast spectroscopy advances, we prepared the superfolder green fluorescent protein (sfGFP) and its non-canonical amino acid (ncAA) derivatives with a single chlorine, bromine, and nitro substituent at the ortho site to the phenolate oxygen of the embedded chromophore, and characterized them using an integrated toolset of femtosecond transient absorption and tunable femtosecond stimulated Raman spectroscopy (FSRS), aided by quantum calculations of the vibrational normal modes. A dominant vibrational cooling time constant of ~4 and 11 ps is revealed in Cl-GFP and Br-GFP, respectively, facilitating a ~30 and 12% increase of the fluorescent quantum yield vs. the parent sfGFP. Similar time constants were also retrieved from the transient absorption spectra, substantiating the correlated electronic and vibrational motions on the intrinsic molecular timescales. Key carbon-halogen stretching motions coupled with phenolate ring motions of the deprotonated chromophores at ca. 908 and 890 cm-1 in Cl-GFP and Br-GFP exhibit enhanced activities in the electronic excited state and blue-shift during a distinct vibrational cooling process on the ps timescale. The retrieved structural dynamics change due to targeted site-specific halogenation of the chromophore thus provides an effective means to design new GFP derivatives and enrich the bioimaging probe toolset for life and medical sciences.
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Affiliation(s)
- Breland G. Oscar
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
| | - Hayati Wolfendeen
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States
| | - Nikita D. Rozanov
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, United States
| | - Alvin Chang
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, United States
| | - Kenneth T. Stout
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, United States
| | - Jason W. Sandwisch
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
| | - Joseph J. Porter
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States
| | - Ryan A. Mehl
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States
| | - Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, OR, United States
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41
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Krueger TD, Boulanger SA, Zhu L, Tang L, Fang C. Discovering a rotational barrier within a charge-transfer state of a photoexcited chromophore in solution. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:024901. [PMID: 32161777 PMCID: PMC7056454 DOI: 10.1063/1.5143441] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/18/2020] [Indexed: 05/15/2023]
Abstract
Methylation occurs in a myriad of systems with protective and regulatory functions. 8-methoxypyrene-1,3,6-trisulfonate (MPTS), a methoxy derivative of a photoacid, serves as a model system to study effects of methylation on the excited state potential energy landscape. A suite of spectroscopic techniques including transient absorption, wavelength-tunable femtosecond stimulated Raman spectroscopy (FSRS), and fluorescence quantum yield measurements via steady-state electronic spectroscopy reveal the energy dissipation pathways of MPTS following photoexcitation. Various solvents enable a systematic characterization of the H-bonding interaction, viscosity, and dynamic solvation that influence the ensuing relaxation pathways. The formation of a charge-transfer state out of the Franck-Condon region occurs on the femtosecond-to-picosecond solvation timescale before encountering a rotational barrier. The rotational relaxation correlates with the H-bond donating strength of solvent, while the rotational time constant lengthens as solvent viscosity increases. Time-resolved excited-state FSRS, aided by quantum calculations, provides crucial structural dynamics knowledge and reveals the sulfonate groups playing a dominant role during solvation. Several prominent vibrational motions of the pyrene ring backbone help maneuver the population toward the more fluorescent state. These ultrafast correlated electronic and nuclear motions ultimately govern the fate of the photoexcited chromophore in solution. Overall, MPTS in water displays the highest probability to fluoresce, while the aprotic and more viscous dimethyl sulfoxide enhances the nonradiative pathways. These mechanistic insights may apply robustly to other photoexcited chromophores that do not undergo excited-state proton transfer or remain trapped in a broad electronic state and also provide design principles to control molecular optical responses with site-specific atomic substitution.
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Affiliation(s)
- Taylor D. Krueger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Sean A. Boulanger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
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42
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Fang C, Tang L. Mapping Structural Dynamics of Proteins with Femtosecond Stimulated Raman Spectroscopy. Annu Rev Phys Chem 2020; 71:239-265. [PMID: 32075503 DOI: 10.1146/annurev-physchem-071119-040154] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The structure-function relationships of biomolecules have captured the interest and imagination of the scientific community and general public since the field of structural biology emerged to enable the molecular understanding of life processes. Proteins that play numerous functional roles in cellular processes have remained in the forefront of research, inspiring new characterization techniques. In this review, we present key theoretical concepts and recent experimental strategies using femtosecond stimulated Raman spectroscopy (FSRS) to map the structural dynamics of proteins, highlighting the flexible chromophores on ultrafast timescales. In particular, wavelength-tunable FSRS exploits dynamic resonance conditions to track transient-species-dependent vibrational motions, enabling rational design to alter functions. Various ways of capturing excited-state chromophore structural snapshots in the time and/or frequency domains are discussed. Continuous development of experimental methodologies, synergistic correlation with theoretical modeling, and the expansion to other nonequilibrium, photoswitchable, and controllable protein systems will greatly advance the chemical, physical, and biological sciences.
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Affiliation(s)
- Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA;
| | - Longteng Tang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA;
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43
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Chen C, Zhu L, Boulanger SA, Baleeva NS, Myasnyanko IN, Baranov MS, Fang C. Ultrafast excited-state proton transfer dynamics in dihalogenated non-fluorescent and fluorescent GFP chromophores. J Chem Phys 2020; 152:021101. [PMID: 31941340 DOI: 10.1063/1.5138666] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Green fluorescent protein (GFP) has enabled a myriad of bioimaging advances due to its photophysical and photochemical properties. To deepen the mechanistic understanding of such light-induced processes, novel derivatives of GFP chromophore p-HBDI were engineered by fluorination or bromination of the phenolic moiety into superphotoacids, which efficiently undergo excited-state proton transfer (ESPT) in aqueous solution within the short lifetime of the excited state, as opposed to p-HBDI where efficient ESPT is not observed. In addition, we tuned the excited-state lifetime from picoseconds to nanoseconds by conformational locking of the p-HBDI backbone, essentially transforming the nonfluorescent chromophores into highly fluorescent ones. The unlocked superphotoacids undergo a barrierless ESPT without much solvent activity, whereas the locked counterparts exhibit two distinct solvent-involved ESPT pathways. Comparative analysis of femtosecond transient absorption spectra of these unlocked and locked superphotoacids reveals that the ESPT rates adopt an "inverted" kinetic behavior as the thermodynamic driving force increases upon locking the backbone. Further experimental and theoretical investigations are expected to shed more light on the interplay between the modified electronic structure (mainly by dihalogenation) and nuclear motions (by conformational locking) of the functionalized GFP derivatives (e.g., fluorescence on and off).
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Affiliation(s)
- Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Sean A Boulanger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Nadezhda S Baleeva
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Ivan N Myasnyanko
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Mikhail S Baranov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
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44
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Krueger TD, Tang L, Zhu L, Breen IL, Wachter RM, Fang C. Dual Illumination Enhances Transformation of an Engineered Green-to-Red Photoconvertible Fluorescent Protein. Angew Chem Int Ed Engl 2020; 59:1644-1652. [PMID: 31692171 DOI: 10.1002/anie.201911379] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Indexed: 01/13/2023]
Abstract
The molecular mechanisms for the photoconversion of fluorescent proteins remain elusive owing to the challenges of monitoring chromophore structural dynamics during the light-induced processes. We implemented time-resolved electronic and stimulated Raman spectroscopies to reveal two hidden species of an engineered ancestral GFP-like protein LEA, involving semi-trapped protonated and trapped deprotonated chromophores en route to photoconversion in pH 7.9 buffer. A new dual-illumination approach was examined, using 400 and 505 nm light simultaneously to achieve faster conversion and higher color contrast. Substitution of UV irradiation with visible light benefits bioimaging, while the spectral benchmark of a trapped chromophore with characteristic ring twisting and bridge-H bending motions enables rational design of functional proteins. With the improved H-bonding network and structural motions, the photoexcited chromophore could increase the photoswitching-aided photoconversion while reducing trapped species.
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Affiliation(s)
- Taylor D Krueger
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331, USA
| | - Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331, USA
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331, USA
| | - Isabella L Breen
- School of Molecular Sciences, Center for Bioenergy and Photosynthesis, Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ, 85287, USA
| | - Rebekka M Wachter
- School of Molecular Sciences, Center for Bioenergy and Photosynthesis, Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ, 85287, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97331, USA
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45
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Krueger TD, Tang L, Zhu L, Breen IL, Wachter RM, Fang C. Dual Illumination Enhances Transformation of an Engineered Green‐to‐Red Photoconvertible Fluorescent Protein. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201911379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Taylor D. Krueger
- Department of Chemistry Oregon State University 153 Gilbert Hall Corvallis OR 97331 USA
| | - Longteng Tang
- Department of Chemistry Oregon State University 153 Gilbert Hall Corvallis OR 97331 USA
| | - Liangdong Zhu
- Department of Chemistry Oregon State University 153 Gilbert Hall Corvallis OR 97331 USA
| | - Isabella L. Breen
- School of Molecular Sciences Center for Bioenergy and Photosynthesis Biodesign Center for Applied Structural Discovery Arizona State University Tempe AZ 85287 USA
| | - Rebekka M. Wachter
- School of Molecular Sciences Center for Bioenergy and Photosynthesis Biodesign Center for Applied Structural Discovery Arizona State University Tempe AZ 85287 USA
| | - Chong Fang
- Department of Chemistry Oregon State University 153 Gilbert Hall Corvallis OR 97331 USA
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46
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Li C, Hu B, Liu Y. Unraveling the effect of two different polar solvents on the excited-state intramolecular proton transfer of 4'-methoxy-3-hydroxyflavone fluorescent dye. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 225:117487. [PMID: 31476648 DOI: 10.1016/j.saa.2019.117487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 08/15/2019] [Accepted: 08/24/2019] [Indexed: 06/10/2023]
Abstract
The fluorescence properties of 4'-methoxy-3-hydroxyflavone (M3HF) dye in different solvents were investigated through experimental (Phys. Chem. Chem. Phys., 2018, 20, 7885) and theoretical (Org. Chem. Front., 2019, 6, 218) methods. However, the intermolecular hydrogen bonds between M3HF and solvents were ignored. In this work, we investigated the effect of methanol (MeOH) and N,N-dimethylformamide (DMF) solvents on the excited-state intramolecular proton transfer (ESIPT) of M3HF fluorescent dye. In excited state (S1), the intramolecular hydrogen bonds are significantly strengthened, which can facilitate the ESIPT processes. The calculated absorption and fluorescence spectra agree well with the experimental date. The fluorescence spectra of M3HF and ESIPT tautomers (T⁎) were found to be sensitive to the solvent polarity. Upon photo-excitation, the electron density of the M3HF molecular is redistributed, which can provide driving force for the ESIPT. The polar solvents MeOH (hydrogen bond donor) and DMF (hydrogen bond acceptor) can form different types of intermolecular hydrogen bonds with M3HF. The two different bonding modes of intermolecular hydrogen bonds are expected to weaken the intramolecular hydrogen bond of M3HF to varying degrees. The analysis of the potential energy curves indicate that the ESIPT processes of M3HF can be hindered by the intermolecular hydrogen bonds. The intermolecular hydrogen bond of M3HF-DMF complex is weaker than that of M3HF-MeOH complex, while the potential barrier of the ESIPT process in DMF solvent is higher than that of in the MeOH solvent. This is principally because, in DMF solvent, the hydroxyl group H1 atom of M3HF can be captured by the O3 atom of DMF and form O3H1 bond with O3 atom in the intermediate process of ESIPT. There appears an energy barrier hopping point on the potential energy curve of M3HF in DMF solvent but does not appear in MeOH solvent.
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Affiliation(s)
- Chaozheng Li
- School of Mechanical and Electrical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, China.
| | - Bo Hu
- School of Mechanical and Electrical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Yufang Liu
- College of Physics and Materials Science, Henan Normal University, Xinxiang 453007, China
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47
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Joung JF, Lee J, Hwang J, Choi K, Park S. A new visible light triggered Arrhenius photobase and its photo-induced reactions. NEW J CHEM 2020. [DOI: 10.1039/c9nj05404a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Visible light triggered Arrhenius photobases are of potential use for excited state hydroxide ion dissociation (ESHID), photo-induced pOH jump experiments, and base-catalyzed reactions.
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Affiliation(s)
- Joonyoung F. Joung
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Jeeun Lee
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Joungin Hwang
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Kihang Choi
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Sungnam Park
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
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48
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Fang C, Tang L, Chen C. Unveiling coupled electronic and vibrational motions of chromophores in condensed phases. J Chem Phys 2019; 151:200901. [PMID: 31779327 DOI: 10.1063/1.5128388] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The quest for capturing molecular movies of functional systems has motivated scientists and engineers for decades. A fundamental understanding of electronic and nuclear motions, two principal components of the molecular Schrödinger equation, has the potential to enable the de novo rational design for targeted functionalities of molecular machines. We discuss the development and application of a relatively new structural dynamics technique, femtosecond stimulated Raman spectroscopy with broadly tunable laser pulses from the UV to near-IR region, in tracking the coupled electronic and vibrational motions of organic chromophores in solution and protein environments. Such light-sensitive moieties hold broad interest and significance in gaining fundamental knowledge about the intramolecular and intermolecular Hamiltonian and developing effective strategies to control macroscopic properties. Inspired by recent experimental and theoretical advances, we focus on the in situ characterization and spectroscopy-guided tuning of photoacidity, excited state proton transfer pathways, emission color, and internal conversion via a conical intersection.
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Affiliation(s)
- Chong Fang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Longteng Tang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Cheng Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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49
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Tang L, Zhu L, Ener ME, Gao H, Wang Y, Groves JT, Spiro TG, Fang C. Photoinduced charge flow inside an iron porphyrazine complex. Chem Commun (Camb) 2019; 55:13606-13609. [PMID: 31657387 PMCID: PMC11076153 DOI: 10.1039/c9cc06193b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Tracking inorganic photochemistry with high resolution poses considerable challenges. Here, sub-picosecond electronic and structural motions and MLCT/d-d intersystem crossing in a cationic iron-porphyrazine are probed using ultrafast transient absorption, stimulated Raman spectroscopy, and quantum calculations. By delineating photoinduced energy relaxation, strategies for extending the lifetime of MLCT state are discussed.
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Affiliation(s)
- Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
| | - Maraia E Ener
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA.
| | - Hongxin Gao
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Yanli Wang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
| | - John T Groves
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Thomas G Spiro
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA.
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA.
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Jen M, Jeon K, Lee S, Hwang S, Chung WJ, Pang Y. Ultrafast intramolecular proton transfer reactions and solvation dynamics of DMSO. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:064901. [PMID: 31867409 PMCID: PMC6920016 DOI: 10.1063/1.5129446] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 11/21/2019] [Indexed: 05/27/2023]
Abstract
Ultrafast intramolecular proton transfers of 1,2-dihydroxyanthraquinone (alizarin-h2) and its deuterated product (alizarin-d2) in dimethyl sulfoxide (DMSO) have been investigated by femtosecond stimulated Raman spectroscopy. The population dynamics in the solute vibrational mode of νC=O and the coherent oscillations observed in all of the skeletal vibrational modes νC=O and νC=C clearly showed the ultrafast excited-state intramolecular proton transfer dynamics of 110 and 170 fs for alizarin-h2 and alizarin-d2, respectively. Interestingly, we have observed that the solvent vibrational modes νS=O and νCSC may also represent ultrafast structural dynamics at the frequencies for its "free" or "aggregated" species. From the kinetic analysis of the νS=O and νCSC modes of DMSO, the ultrafast changes in the solvation or intermolecular interactions between DMSO molecules initiated by the structural changes of solute molecules have been thoroughly investigated. We propose that the solvent vibrational modes νS=O and νCSC of DMSO can be used as a "sensor" for ultrafast chemical reactions accompanying the structural changes and subsequent solute-solvent interactions.
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Affiliation(s)
| | | | - Sebok Lee
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, South Korea
| | - Sunjoo Hwang
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, South Korea
| | - Won-jin Chung
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, South Korea
| | - Yoonsoo Pang
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, South Korea
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