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Joung JF, Jeong M, Park S. Reliable experimental method for determination of photoacidity revealed by quantum chemical calculations. Phys Chem Chem Phys 2022; 24:21714-21721. [PMID: 36074805 DOI: 10.1039/d2cp03308a] [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
Photoacids are aromatic acids that exhibit significantly different acidities when they are electronically excited. Three experimental methods have been extensively used to determine the photoacidity, : fluorescence titration, the Förster cycle, and time-resolved experiments. However, the photoacidities determined by these experimental methods are not consistent. In this work, we used a theoretical method to evaluate the reliability of experimentally determined values. In particular, density functional theory (DFT) and time-dependent DFT calculations were used to obtain the changes in Gibbs free energy for acid dissociation reactions which are directly related to values. The Förster cycle, which is frequently used to experimentally determine the photoacidity due to its simplicity, yielded inconsistent results depending on how the transition energy was defined. We evaluated six empirical parameters extracted from the absorption and emission spectra of acidic and basic species of photoacids to adequately define the transition energy in the Förster cycle. And we found that the values obtained using the optical bandgap as the transition energy in the Förster cycle were in the best agreement with the results of quantum chemical calculations.
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Affiliation(s)
- Joonyoung F Joung
- Department of Chemistry and Research Institute for Natural Science, Korea University, Seoul, 02841, Korea.
| | - Minseok Jeong
- Department of Chemistry and Research Institute for Natural Science, Korea University, Seoul, 02841, Korea.
| | - Sungnam Park
- Department of Chemistry and Research Institute for Natural Science, Korea University, Seoul, 02841, Korea.
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2
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Cruz L, Basílio N, Mateus N, de Freitas V, Pina F. Natural and Synthetic Flavylium-Based Dyes: The Chemistry Behind the Color. Chem Rev 2021; 122:1416-1481. [PMID: 34843220 DOI: 10.1021/acs.chemrev.1c00399] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Flavylium compounds are a well-known family of pigments because they are prevalent in the plant kingdom, contributing to colors over a wide range from shades of yellow-red to blue in fruits, flowers, leaves, and other plant parts. Flavylium compounds include a large variety of natural compound classes, namely, anthocyanins, 3-deoxyanthocyanidins, auronidins, and their respective aglycones as well as anthocyanin-derived pigments (e.g., pyranoanthocyanins, anthocyanin-flavan-3-ol dimers). During the past few decades, there has been increasing interest among chemists in synthesizing different flavylium compounds that mimic natural structures but with different substitution patterns that present a variety of spectroscopic characteristics in view of their applications in different industrial fields. This Review provides an overview of the chemistry of flavylium-based compounds, in particular, the synthetic and enzymatic approaches and mechanisms reported in the literature for obtaining different classes of pigments, their physical-chemical properties in relation to their pH-dependent equilibria network, and their chemical and enzymatic degradation. The development of flavylium-based systems is also described throughout this Review for emergent applications to explore some of the physical-chemical properties of the multistate of species generated by these compounds.
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Affiliation(s)
- Luis Cruz
- LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Nuno Basílio
- LAQV-REQUIMTE, Department of Chemistry, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal
| | - Nuno Mateus
- LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Victor de Freitas
- LAQV-REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Fernando Pina
- LAQV-REQUIMTE, Department of Chemistry, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal
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Excited state proton transfer in reverse micelles: Effect of temperature and a possible interplay with solvation. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2020.112928] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Oliveira H, Correia P, Pereira AR, Araújo P, Mateus N, de Freitas V, Oliveira J, Fernandes I. Exploring the Applications of the Photoprotective Properties of Anthocyanins in Biological Systems. Int J Mol Sci 2020; 21:E7464. [PMID: 33050431 PMCID: PMC7589295 DOI: 10.3390/ijms21207464] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/02/2020] [Accepted: 10/07/2020] [Indexed: 12/13/2022] Open
Abstract
Due to their physical and chemical characteristics, anthocyanins are amongst the most versatile groups of natural compounds. Such unique signature makes these compounds a focus in several different areas of research. Anthocyanins have well been reported as bioactive compounds in a myriad of health disorders such as cardiovascular diseases, cancer, and obesity, among others, due to their anti-inflammatory, antioxidant, anti-diabetic, anti-bacterial, and anti-proliferative capacities. Such a vast number of action mechanisms may be also due to the number of structurally different anthocyanins plus their related derivatives. In this review, we highlight the recent advances on the potential use of anthocyanins in biological systems with particular focus on their photoprotective properties. Topics such as skin aging and eye degenerative diseases, highly influenced by light, and the action of anthocyanins against such damages will be discussed. Photodynamic Therapy and the potential role of anthocyanins as novel photosensitizers will be also a central theme of this review.
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Affiliation(s)
| | | | | | | | | | | | - Joana Oliveira
- LAQV, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal; (H.O.); (P.C.); (A.R.P.); (P.A.); (N.M.); (V.d.F.)
| | - Iva Fernandes
- LAQV, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal; (H.O.); (P.C.); (A.R.P.); (P.A.); (N.M.); (V.d.F.)
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Silva GTM, Thomas SS, Silva CP, Schlothauer JC, Baptista MS, Freitas AA, Bohne C, Quina FH. Triplet Excited States and Singlet Oxygen Production by Analogs of Red Wine Pyranoanthocyanins. Photochem Photobiol 2018; 95:176-182. [PMID: 29978920 DOI: 10.1111/php.12973] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 06/22/2018] [Indexed: 01/07/2023]
Abstract
During the maturation of red wines, the anthocyanins of grapes are transformed into pyranoanthocyanins, which possess a pyranoflavylium cation as their basic chromophore. Photophysical properties of the singlet and triplet excited states of a series of synthetic pyranoflavylium cations were determined at room temperature in acetonitrile solution acidified with 0.10 mol dm-3 trifluoroacetic acid (TFA, to inhibit competitive excited state proton transfer) and at 77 K in a rigid TFA-acidified isopropanol glass. In solution, the triplet states of these pyranoflavylium cations are efficiently quenched by molecular oxygen, resulting in sensitized formation of singlet oxygen, as confirmed by direct detection of the triplet-state decay by laser flash photolysis and of singlet oxygen monomol emission in the near infrared. The strong visible light absorption, the relatively small singlet-triplet energy differences, the excited state redox potentials and the reasonably long lifetimes of pyranoflavylium triplet states in the absence of molecular oxygen suggest that they might be useful as triplet sensitizers and/or as cationic redox initiators in polar aprotic solvents like acetonitrile.
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Affiliation(s)
- Gustavo Thalmer M Silva
- Department of Fundamental Chemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Suma S Thomas
- Department of Chemistry and Centre for Advanced Materials and Related Technologies (CAMTEC), University of Victoria, Victoria, BC, Canada
| | - Cassio Pacheco Silva
- Department of Fundamental Chemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Jan C Schlothauer
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Mauricio S Baptista
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Adilson A Freitas
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Cornelia Bohne
- Department of Chemistry and Centre for Advanced Materials and Related Technologies (CAMTEC), University of Victoria, Victoria, BC, Canada
| | - Frank H Quina
- Department of Fundamental Chemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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Freitas AA, Silva CP, Silva GTM, Maçanita AL, Quina FH. Ground- and Excited-State Acidity of Analogs of Red Wine Pyranoanthocyanins,. Photochem Photobiol 2018; 94:1086-1091. [DOI: 10.1111/php.12944] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 05/23/2018] [Indexed: 01/19/2023]
Affiliation(s)
- Adilson A. Freitas
- Centro de Química Estrutural; Instituto Superior Técnico; Universidade de Lisboa; Lisbon Portugal
| | - Cassio Pacheco Silva
- Instituto de Química; Cidade Universitária; Universidade de São Paulo; São Paulo Brazil
| | | | - António L. Maçanita
- Centro de Química Estrutural; Instituto Superior Técnico; Universidade de Lisboa; Lisbon Portugal
| | - Frank H. Quina
- Instituto de Química; Cidade Universitária; Universidade de São Paulo; São Paulo Brazil
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Aguilar-Castillo BA, Sánchez-Bojorge NA, Chávez-Flores D, Camacho-Dávila AA, Pasillas-Ornelas E, Rodríguez-Valdez LM, Zaragoza-Galán G. Naphtyl- and pyrenyl-flavylium dyads: Synthesis, DFT and optical properties. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2017.11.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Duarte LGTA, Germino JC, Braga CDÁ, Barboza CA, Atvars TDZ, Santos FDS, Rodembusch FS. Photoacidity as a tool to rationalize excited state intramolecular proton transfer reactivity in flavonols. Photochem Photobiol Sci 2018; 17:231-238. [DOI: 10.1039/c7pp00334j] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Determination of acidic strengths at the electronic ground and excited states of flavonol derivatives.
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Affiliation(s)
| | | | - Cláudia de Ávila Braga
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada
- Universidade Federal do Rio Grande do Sul
- Instituto de Química
- Porto Alegre
- Brazil
| | | | | | - Fabiano da Silveira Santos
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada
- Universidade Federal do Rio Grande do Sul
- Instituto de Química
- Porto Alegre
- Brazil
| | - Fabiano Severo Rodembusch
- Grupo de Pesquisa em Fotoquímica Orgânica Aplicada
- Universidade Federal do Rio Grande do Sul
- Instituto de Química
- Porto Alegre
- Brazil
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QUINA FRANKH, BASTOS ERICKL. Chemistry Inspired by the Colors of Fruits, Flowers and Wine. ACTA ACUST UNITED AC 2018; 90:681-695. [DOI: 10.1590/0001-3765201820170492] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/25/2017] [Indexed: 11/22/2022]
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From vine to wine: photophysics of a pyranoflavylium analog of red wine pyranoanthocyanins. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2017-0411] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractIn the ground state, the p-methoxyphenyl-substituted pyranoflavylium cation I, prepared by the reaction of the 5,7-dihydroxy-4-methylflavylium cation with p-methoxybenzaldehyde, is a weak acid (pKa=3.7±0.1). In its lowest excited singlet state, I is a moderate photoacid (pKa*=0.67) in 30% methanol-water acidified with trifluoroacetic acid (TFA). In comparison to anthocyanins and 7-hydroxyflavylium cations, the photoacidity of I is much less pronounced and the rate of proton loss from the excited acid form of I much slower (by a factor of up to 100). In 50% ethanol:0.10 mol dm−3 HClO4, the excited state of the acid form of I undergoes fast (12 ps) initial relaxation (potentially in the direction of an intramolecular charge transfer state), followed by much slower (340 ps) adiabatic deprotonation to form the excited base. The excited base in turn exhibits a moderately fast relaxation (70 ps), consistent with solvent hydrogen-bond reorganization times, followed by slower but efficient decay (1240 ps) back to the ground state. As in uncomplexed anthocyanins and 7-hydroxyflavylium cations, the photophysical behavior of I points to excited state proton transfer as the dominant excited state deactivation pathway of pyranoanthocyanins, consistent with relatively good photostability of natural pyranoanthocyanins.
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Silva VO, Freitas AA, Maçanita AL, Quina FH. Chemistry and photochemistry of natural plant pigments: the anthocyanins. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3534] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Volnir O. Silva
- Instituto de Química; Universidade de São Paulo; São Paulo CP 26077, 05513-970 Brazil
| | - Adilson A. Freitas
- Centro de Química Estrutural, Instituto Superior Técnico; Universidade de Lisboa; Lisbon Portugal
| | - António L. Maçanita
- Centro de Química Estrutural, Instituto Superior Técnico; Universidade de Lisboa; Lisbon Portugal
| | - Frank H. Quina
- Instituto de Química; Universidade de São Paulo; São Paulo CP 26077, 05513-970 Brazil
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Joung JF, Kim S, Park S. Effect of NaCl Salts on the Activation Energy of Excited-State Proton Transfer Reaction of Coumarin 183. J Phys Chem B 2015; 119:15509-15. [DOI: 10.1021/acs.jpcb.5b09905] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Sangin Kim
- Department of Chemistry, Korea University, Seoul 136-701, Korea
| | - Sungnam Park
- Department of Chemistry, Korea University, Seoul 136-701, Korea
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Seixas de Melo JS, Maçanita AL. Unveiling the Eigen-Weller ion pair from the excited state proton transfer kinetics of 3-chloro-4-methyl-7-hydroxycoumarin. J Phys Chem B 2014; 119:2604-10. [PMID: 25325432 DOI: 10.1021/jp508782h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The prototropic reactions of the first excited singlet state of 3-chloro-4-methylumbelliferone (3Cl4MU), in dioxane:water mixtures (Dx:H2O), were revisited using ps-time-resolved fluorescence techniques. The data response to the dielectric constant of the mixtures revealed the presence of an additional fourth kinetic species, kinetically coupled to the neutral (N*), the tautomeric (T*), and anionic (A(-)*) forms of 3Cl4MU, which is assigned to the elusive geminate (A(-)*···H(+)) ion pair. From the data analysis, all rate constants of the prototropic and diffusion processes involved were separately evaluated. The results showed that, whenever the geminate ionic pair is not kinetically detected, the evaluated values for deprotonation and protonation rate constants can substantially deviate from the real ones, depending on the efficiencies of pair recombination and dissociation. Finally, the results provide convincing kinetic evidence for the Eigen-Weller mechanism (intermediacy of the geminate ionic pair) in a quasi-aqueous medium, which to our knowledge had not yet been given.
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Affiliation(s)
- J Sérgio Seixas de Melo
- Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra , Rua Larga, 3004-535 Coimbra, Portugal
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