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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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Ab initio investigation of substituent effects on the excited electronic states of flavylium cation analogues of anthocyanin pigments. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Martins LMOS, Wang X, Silva GTM, Junqueira HC, Fornaciari B, Lopes LF, Silva CP, Zhou P, Cavalcante VF, Baptista MS, Quina FH. Red Wine Inspired Chromophores as Photodynamic Therapy Sensitizers. Photochem Photobiol 2022; 99:732-741. [PMID: 35944220 DOI: 10.1111/php.13682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/25/2022] [Indexed: 11/30/2022]
Abstract
Hydroxypyranoflavylium (HPF) cations are synthetic analogs possessing the same basic chromophore as the pyranoanthocyanins that form during the maturation of red wine. HPF cations absorb strongly in the visible spectral region, and most are fluorescent, triplet-sensitize singlet oxygen formation in solution and are strong photooxidants, properties that are desirable in a sensitizer for photodynamic therapy (PDT). The results of this study demonstrate that several simple HPF dyes can indeed function as PDT sensitizers. Of the eight HPF cations investigated in this work, four were phototoxic to a human cervical adenocarcinoma cell line (HeLa) at the 1-10 μmol dm-3 level, while only one of the eight compounds showed noticeable cytotoxicity in the dark. Neither a Type I nor a Type II mechanism can adequately rationalize the differences in phototoxicity of the compounds. Colocalization experiments with the most phototoxic compound demonstrated the affinity of the dye for both the mitochondria and lysosomes of HeLa cells. The fact that relatively modest structural differences, e.g., the exchange of an electron-donating substituent for an electron-withdrawing substituent, can cause profound differences in the phototoxicity, together with the relatively facile synthesis of substituted HPF cations, makes them interesting candidates for further evaluation as PDT sensitizers.
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Affiliation(s)
- Lucas M. O. S. Martins
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Xuhui Wang
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
- National University of Singapore
| | - Gustavo T. M. Silva
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Helena C. Junqueira
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Bárbara Fornaciari
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Lohanna F. Lopes
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Cassio P. Silva
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Peng Zhou
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
- School of Pharmaceutical Science and Technology Tianjin University Tianjin China
- Tsinghua University Beijing China
| | - Victor F. Cavalcante
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Mauricio S. Baptista
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
| | - Frank H. Quina
- Instituto de Química, Universidade de São Paulo Av. Lineu Prestes 748 São Paulo 05508‐900 Brazil
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