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Ohira K, Kozuka K, Kaneda N, Yamamoto M, Imato K, Ooyama Y. Photochromism of phenazine-2,3-diol derivatives through excited state intermolecular proton transfer based on keto-enol tautomerization. Org Biomol Chem 2024; 22:4077-4088. [PMID: 38629338 DOI: 10.1039/d4ob00387j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Photochromism through excited-state intermolecular proton transfer (ESInterPT) processes based on keto-enol tautomerization was found in phenazine-2,3-diol PD1 and its monoalkoxy derivative PD2 in a glassy matrix at 77 K: the colorless solutions of enol forms PD1-E and PD2-E at 298 K transformed into orange-colored solutions of keto forms PD1-K and PD2-K upon photoirradiation (λ = 385 nm) at 77 K. Furthermore, this report is the first to achieve the single-crystal X-ray structural analyses of phenazine-2,3-diol PD1 and its monoalkoxy derivative PD2, since the report on the synthesis of PD1 70 years ago. Indeed, it was found that PD1 and PD2 molecules exist in the keto form (PD1-K) and the enol form (PD2-E), respectively, in the crystal, and the neighboring PD1-K and PD2-E molecules are linked by one-dimensional intermolecular NH⋯O and OH⋯N hydrogen bonding, respectively. The fact suggests strongly that for PD1 and PD2, the formation of continuous intermolecular hydrogen bonding in aggregates such as in a glassy matrix at 77 K is involved in the keto-enol tautomerization of phenazine-2,3-diol derivatives based on ESInterPT. More interestingly, the color and the photoabsorption spectrum of the solids obtained by sublimation of crystals of PD2-E are similar to those for the crystals of PD1-K, indicating that the PD2 molecule exists in the keto form (PD2-K) in the solid of the sublimate. Therefore, this study provides a valuable insight for a greater understanding of the keto-enol tautomerization of diazaacene-diol derivatives and their photophysical properties in the solution and in the solid state.
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Affiliation(s)
- Kazuki Ohira
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
| | - Kumpei Kozuka
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
| | - Naoki Kaneda
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
| | - Masahiro Yamamoto
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
| | - Keiichi Imato
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
| | - Yousuke Ooyama
- Applied Chemistry Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
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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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Zhu H, Gong F, Ma P, Qian Y, He L, Chen L, Qin X, Xu L. Protein-activated and FRET enhanced excited-state intermolecular proton transfer fluorescent probes for high-resolution imaging of cilia and tunneling nanotubes in live cells. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 288:122142. [PMID: 36446173 DOI: 10.1016/j.saa.2022.122142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/13/2022] [Accepted: 11/20/2022] [Indexed: 06/16/2023]
Abstract
Excited-state intermolecular proton transfer (inter-ESPT) fluorescent probes responsive to specific bioactive molecules should be greatly promising for protein sensing, DNA mutation simulating and cellular process regulating. However, the inter-ESPT molecules are recessive ESPT fluorophores, which need the assistance of other molecules with both hydrogen-bond accepting and donating abilities to turn on the tautomeric fluorescence. Valid design strategies to create powerful inter-ESPT fluorescent probes are poorly developed, particularly for proteins as targets. We recently reported a unique supramolecular strategy to trigger the inter-ESPT process based on the probe-protein recognition by H-bonding and to image protein-based subcellular structures in live cells. Herein, we found that our inter-ESPT probes (inter-ESPT-01) bearing a 2-amino-3-cyanopyridine scaffold can anchor proteins and light up the "invisible" ESPT state, so as to image the proteins or the protein-based subcellular organelles. More importantly, the inter-ESPT emission of inter-ESPT-01 can be significantly enhanced by the FRET process between amino and imino tautomers, endowing the inter-ESPT-01 probes with super-bright tautomeric fluorescence. The expressed proteins Ecallantide and MarTX were selected as the models to light up the inter-ESPT fluorescence of the probes and revealed that the inter-ESPT process can be triggered by the specific probe-protein recognition events. In the use of the super-bright inter-ESPT fluorescence, not only the proteins, but also the protein-based cilia and tunneling nanotubes (TNTs) can be specifically visualized in living cancer cells. Furthermore, such recognition-driven strategy allows us to construct a unique inter-ESPT probe to track and image specific endogenous proteins in live cells, highlighting the potential of inter-ESPT fluorogens as novel intelligent biomaterials.
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Affiliation(s)
- Hanming Zhu
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - Fuchun Gong
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China.
| | - Pan Ma
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - You Qian
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - Lingzhi He
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - Lusen Chen
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - Xiaoling Qin
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
| | - Lujie Xu
- College of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, PR China
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Mukherjee S, Jimenez R. Photophysical Engineering of Fluorescent Proteins: Accomplishments and Challenges of Physical Chemistry Strategies. J Phys Chem B 2022; 126:735-750. [DOI: 10.1021/acs.jpcb.1c05629] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Srijit Mukherjee
- JILA, University of Colorado at Boulder and National Institute of Standards and Technology, 440 UCB, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado at Boulder, 215 UCB, Boulder, Colorado 80309, United States
| | - Ralph Jimenez
- JILA, University of Colorado at Boulder and National Institute of Standards and Technology, 440 UCB, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado at Boulder, 215 UCB, Boulder, Colorado 80309, United States
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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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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: 32] [Impact Index Per Article: 8.0] [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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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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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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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: 32] [Impact Index Per Article: 6.4] [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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Chen C, Zhu L, Baranov MS, Tang L, Baleeva NS, Smirnov AY, Yampolsky IV, Solntsev KM, Fang C. Photoinduced Proton Transfer of GFP-Inspired Fluorescent Superphotoacids: Principles and Design. J Phys Chem B 2019; 123:3804-3821. [DOI: 10.1021/acs.jpcb.9b03201] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Cheng Chen
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Liangdong Zhu
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - 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
| | - Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Nadezhda S. Baleeva
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Alexander Yu. Smirnov
- Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Ilia V. Yampolsky
- 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
| | - Kyril M. Solntsev
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- New York University Abu Dhabi, P.O. Box 129188, Abu Dhabi, United Arab Emirates
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
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