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Clark JA, Kusy D, Vakuliuk O, Krzeszewski M, Kochanowski KJ, Koszarna B, O'Mari O, Jacquemin D, Gryko DT, Vullev VI. The magic of biaryl linkers: the electronic coupling through them defines the propensity for excited-state symmetry breaking in quadrupolar acceptor-donor-acceptor fluorophores. Chem Sci 2023; 14:13537-13550. [PMID: 38033901 PMCID: PMC10685337 DOI: 10.1039/d3sc03812b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 11/04/2023] [Indexed: 12/02/2023] Open
Abstract
Charge transfer (CT) is key for molecular photonics, governing the optical properties of chromophores comprising electron-rich and electron-deficient components. In photoexcited dyes with an acceptor-donor-acceptor or donor-acceptor-donor architecture, CT breaks their quadrupolar symmetry and yields dipolar structures manifesting pronounced solvatochromism. Herein, we explore the effects of electronic coupling through biaryl linkers on the excited-state symmetry breaking of such hybrid dyes composed of an electron-rich core, i.e., 1,4-dihydropyrrolo[3,2-b]pyrrole (DHPP), and pyrene substituents that can act as electron acceptors. Experimental and theoretical studies reveal that strengthening the donor-acceptor electronic coupling decreases the CT rates and the propensity for symmetry breaking. We ascribe this unexpected result to effects of electronic coupling on the CT thermodynamics, which in its turn affects the CT kinetics. In cases of intermediate electronic coupling, the pyrene-DHPP conjugates produce fluorescence spectra, spreading over the whole visible range, that in addition to the broad CT emission, show bands from the radiative deactivation of the locally excited states of the donor and the acceptors. Because the radiative deactivation of the low-lying CT states is distinctly slow, fluorescence from upper locally excited states emerge leading to the observed anti-Kasha behaviour. As a result, these dyes exhibit white fluorescence. In addition to demonstrating the multifaceted nature of the effects of electronic coupling on CT dynamics, these chromophores can act as broad-band light sources with practical importance for imaging and photonics.
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Affiliation(s)
- John A Clark
- Department of Bioengineering, University of California Riverside, 900 University Ave. Riverside CA 92521 USA
| | - Damian Kusy
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Olena Vakuliuk
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Maciej Krzeszewski
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Krzysztof J Kochanowski
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Beata Koszarna
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Omar O'Mari
- Department of Bioengineering, University of California Riverside, 900 University Ave. Riverside CA 92521 USA
| | - Denis Jacquemin
- Nantes Université, CNRS CEISAM UMR 6230 F-44000 Nantes France
- Institut Universitaire de France (IUF) F-75005 Paris France
| | - Daniel T Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences Kasprzaka 44-52 01-224 Warsaw Poland
| | - Valentine I Vullev
- Department of Bioengineering, University of California Riverside, 900 University Ave. Riverside CA 92521 USA
- Department of Chemistry, University of California Riverside CA 92521 USA
- Department of Biochemistry, University of California Riverside CA 92521 USA
- Materials Science and Engineering Program, University of California Riverside CA 92521 USA
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Szychta K, Koszarna B, Banasiewicz M, Sobolewski A, O’Mari O, Clark JA, Vullev VI, Barboza CA, Gryko DT. Conformation of the Ester Group Governs the Photophysics of Highly Polarized Benzo[ g]coumarins. JACS AU 2023; 3:1918-1930. [PMID: 37502148 PMCID: PMC10369411 DOI: 10.1021/jacsau.3c00169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/10/2023] [Accepted: 06/13/2023] [Indexed: 07/29/2023]
Abstract
Photosensitizers that display "unusual" emission from upper electronically excited states offer possibilities for initiating higher-energy processes than what the governing Kasha's rule postulates. Achieving conditions for dual fluorescence from multiple states of the same species requires molecular design and conditions that favorably tune the excited-state dynamics. Herein, we switch the position of the electron-donating NMe2 group around the core of benzo[g]coumarins (BgCoum) and tune the electronic coupling and the charge-transfer character of the fluorescent excited states. For solvents with intermediate polarity, three of the four regioisomers exhibit fluorescence from two different excited states with bands that are well separated in the visible and the near-infrared spectral regions. Computational analysis, employing ab initio methods, reveals that the orientation of an ester on the pyrone ring produces two conformers responsible for the observed dual fluorescence. Studies with solid solvating media, which restricts the conformational degrees of freedom, concur with the computational findings. These results demonstrate how "seemingly inconsequential" auxiliary substituents, such as the esters on the pyrone coumarin rings, can have profound effects leading to "anti-Kasha" photophysical behavior important for molecular photonics, materials engineering, and solar-energy science.
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Affiliation(s)
- Kamil Szychta
- Institute
of Organic Chemistry of Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Beata Koszarna
- Institute
of Organic Chemistry of Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Marzena Banasiewicz
- Institute
of Physics of Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Andrzej Sobolewski
- Institute
of Physics of Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Omar O’Mari
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
| | - John A. Clark
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
| | - Valentine I. Vullev
- Department
of Bioengineering, University of California, Riverside, California 92521, United States
- Department
of Chemistry, Department of Biochemistry, and Materials Science and
Engineering Program, University of California, Riverside, California 92521, United States
| | - Cristina A. Barboza
- Institute
of Physics of Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
- Department
of Physical and Quantum Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wrocław 50-370, Poland
| | - Daniel T. Gryko
- Institute
of Organic Chemistry of Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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O’Mari O, Vullev VI. Optical Window to Polarity of Electrolyte Solutions. Molecules 2023; 28:4360. [PMID: 37298836 PMCID: PMC10254283 DOI: 10.3390/molecules28114360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/21/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
Medium polarity plays a crucial role in charge-transfer processes and electrochemistry. The added supporting electrolyte in electrochemical setups, essential for attaining the needed electrical conductivity, sets challenges for estimating medium polarity. Herein, we resort to Lippert-Mataga-Ooshika (LMO) formalism for estimating the Onsager polarity of electrolyte organic solutions pertinent to electrochemical analysis. An amine derivative of 1,8-naphthalimide proves to be an appropriate photoprobe for LMO analysis. An increase in electrolyte concentration enhances the polarity of the solutions. This effect becomes especially pronounced for low-polarity solvents. Adding 100 mM tetrabutylammonium hexafluorophosphate to chloroform results in solution polarity exceeding that of neat dichloromethane and 1,2-dichloroethane. Conversely, the observed polarity enhancement that emerges upon the same electrolyte addition to solvents such as acetonitrile and N,N-dimethylformamide is hardly as dramatic. Measured refractive indices provide a means for converting Onsager to Born polarity, which is essential for analyzing medium effects on electrochemical trends. This study demonstrates a robust optical means, encompassing steady-state spectroscopy and refractometry, for characterizing solution properties important for charge-transfer science and electrochemistry.
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Affiliation(s)
- Omar O’Mari
- Department of Bioengineering, University of California, Riverside, CA 92521, USA;
| | - Valentine I. Vullev
- Department of Bioengineering, University of California, Riverside, CA 92521, USA;
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Material Science and Engineering Program, University of California, Riverside, CA 92521, USA
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Mayther MF, O'Mari O, Flacke P, Bhatt D, Andrews S, Vullev VI. How Do Liquid-Junction Potentials and Medium Polarity at Electrode Surfaces Affect Electrochemical Analyses for Charge-Transfer Systems? J Phys Chem B 2023; 127:1443-1458. [PMID: 36735861 DOI: 10.1021/acs.jpcb.2c07983] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The importance of electrochemical analysis for charge-transfer science cannot be overstated. Interfaces in electrochemical cells present certain challenges in the interpretation and the utility of the analysis. This publication focuses on: (1) the medium polarity that redox species experience at the electrode surfaces that is smaller than the polarity in the bulk media and (2) the liquid-junction potentials from interfacing electrolyte solutions of different organic solvents, namely, dichloromethane, benzonitrile, and acetonitrile. Electron-donor-acceptor pairs of aromatics with similar structures (i.e., 1-naphthylamine and 1-nitronaphthalene, 10-methylphenothiazine and 9-nitroanthracene, and 1-aminopyrene and 1-nitropyrene) serve as redox analytes for this study. Using the difference between the reduction potentials of the oxidized donors and the acceptors eliminates the effects of the liquid junctions on the analysis of charge-transfer thermodynamics. This analysis also offers a means for evaluating the medium polarity that the redox species experience at the surface of the working electrode and the effects of the liquid junctions on the measured reduction potentials. While the liquid-junction potentials between the dichloromethane and acetonitrile solutions amount to about 90 mV, for the benzonitrile-acetonitrile junctions, the potentials are only about 30 mV. The presented methods for analyzing the measured electrochemical characteristics of donors and acceptors illustrate a means for improved evaluation of the thermodynamics of charge-transfer systems.
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Affiliation(s)
- Maximillian F Mayther
- Department of Chemistry, University of California, Riverside, California92521, United States
| | - Omar O'Mari
- Department of Bioengineering, University of California, Riverside, California92521, United States
| | - Paul Flacke
- Department of Bioengineering, University of California, Riverside, California92521, United States
| | - Dev Bhatt
- Department of Bioengineering, University of California, Riverside, California92521, United States
| | - Samantha Andrews
- Department of Bioengineering, University of California, Riverside, California92521, United States
| | - Valentine I Vullev
- Department of Chemistry, University of California, Riverside, California92521, United States.,Department of Bioengineering, University of California, Riverside, California92521, United States.,Department of Biochemistry, University of California, Riverside, California92521, United States.,Materials Science and Engineering Program, University of California, Riverside, California92521, United States
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Zhu F, Zou Y, Hua L, Peng X, Zhang W. Redox potential regulated by electrolyte concentration: A case study of electrochemical oxidation of 2,2,6,6-tetramethyl piperidine-1-oxyl. Electrochem commun 2022. [DOI: 10.1016/j.elecom.2022.107374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Espinoza EM, Clark JA, Billones MK, Silva GTDM, da Silva CP, Quina FH, Vullev VI. Photophysics and Electrochemistry of Biomimetic Pyranoflavyliums: What Can Bioinspiration from Red Wines Offer? PHOTOCHEM 2022; 2:9-31. [PMID: 35075451 PMCID: PMC8783599 DOI: 10.3390/photochem2010003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Natural dyes and pigments offer incomparable diversity of structures and functionalities, making them an excellent source of inspiration for the design and development of synthetic chromophores with a myriad of emerging properties. Formed during maturation of red wines, pyranoanthocyanins are electron-deficient cationic pyranoflavylium dyes with broad absorption in the visible spectral region and pronounced chemical and photostability. Herein, we survey the optical and electrochemical properties of synthetic pyranoflavylium dyes functionalized with different electron-donating and electron-withdrawing groups, which vary their reduction potentials over a range of about 400 mV. Despite their highly electron-deficient cores, the exploration of pyranoflavyliums as photosensitizers has been limited to the "classical" n-type dye-sensitized solar cells (DSSCs) where they act as electron donors. In light of their electrochemical and spectroscopic properties, however, these biomimetic synthetic dyes should prove to be immensely beneficial as chromophores in p-type DSSCs, where their ability to act as photooxidants, along with their pronounced photostability, can benefit key advances in solar-energy science and engineering.
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Affiliation(s)
| | - John Anthony Clark
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | | | | | - Cassio Pacheco da Silva
- Instituto de Química, Universidade de São Paulo, Avenida Lineu Prestes 748, Cidade Universitaŕia, São Paulo 05508-900, Brazil
| | - Frank Herbert Quina
- Instituto de Química, Universidade de São Paulo, Avenida Lineu Prestes 748, Cidade Universitaŕia, São Paulo 05508-900, Brazil
| | - Valentine Ivanov Vullev
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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Espinoza EM, Clark JA, Silva CP, Derr JB, Silva GTDM, Billones MK, Morales M, Quina FH, Vullev VI. Charge transfer vs. proton transfer in the excited-state dynamics of biomimetic pyranoflavylium cations. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2022. [DOI: 10.1016/j.jpap.2022.100110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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