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Ghosh G, Roy DS, Ghosh R, Mukherjee D, Biswas S, Roy L, Chattopadhyay A, Das R, Pal SK. Excited-State Dynamics of a Photoacid: A Potential Probe for Recognizing Transition from Lamellar to Nonlamellar Inverted Structures of Liposome based Nanocarriers. Chemphyschem 2024; 25:e202300635. [PMID: 37936318 DOI: 10.1002/cphc.202300635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/04/2023] [Accepted: 11/07/2023] [Indexed: 11/09/2023]
Abstract
Liposomes of a cationic lipid dioctadecyldimethylammonium bromide (DODAB) are efficient nanocarriers of nucleic acids. Incorporation of a neutral lipid monoolein (MO) in excess (xMO >0.5) changes the lamellar organization of DODAB liposomes into non-lamellar inverted structures of DODAB/MO liposomes facilitating nucleic acid delivery to cells. Photoexcitation of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), a photoacid, initiates an excited state proton transfer (ESPT) reaction in its protonated form (ROH*) generating the deprotonated anionic form (RO- *). The fluorescence intensity ratio (IROH* /IRO-* ) of these two forms is governed by the ESPT dynamics, and increases with increasing MO content (xMO ) in the cationic liposomes of DODAB. Transition from lamellar organization of DODAB liposomes into non-lamellar inverted structures of DODAB/MO liposomes, due to incorporation of MO (xMO ~0.7), is manifested by a significant increase of ESPT time (τPT ) and the time constant of wobbling motion (τW ) of HPTS. Thus, the lamellar organizations of DODAB or DODAB-rich (xMO 0.2) liposomes and the non-lamellar organizations of MO-rich (xMO ~0.7) liposomes are recognized by significantly different excited state dynamics of the photoacid.
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Affiliation(s)
- Gourab Ghosh
- Dept. of Chemistry, West Bengal State University, Barasat, Kolkata, 700126, India
| | - Debanjana Singha Roy
- Dept. of Chemistry, West Bengal State University, Barasat, Kolkata, 700126, India
- Department of Chemical, Biological & Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, India
| | - Ria Ghosh
- Technical Research Centre, S. N. Bose National Centre for Basic Sciences, Kolkata, India
| | - Dipanjan Mukherjee
- Department of Chemical, Biological & Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, India
| | - Suman Biswas
- Dept. of Chemistry, West Bengal State University, Barasat, Kolkata, 700126, India
| | - Lopamudra Roy
- Department of Applied Optics and Photonics, University of Calcutta, 92, Acharya Prafulla Chandra Rd, Kolkata, 700009, India
| | - Arpita Chattopadhyay
- Department of Basic science and humanities, Techno International New Town, Rajarhat, Kolkata, 700156
| | - Ranjan Das
- Dept. of Chemistry, West Bengal State University, Barasat, Kolkata, 700126, India
| | - Samir Kumar Pal
- Department of Chemical, Biological & Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata, India
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2
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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: 20] [Impact Index Per Article: 5.0] [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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Alejo-Armijo A, Basílio N, Freitas AA, Maçanita AL, Lima JC, Parola AJ, Pina F. Ground and excited state properties of furanoflavylium derivatives. Phys Chem Chem Phys 2019; 21:21651-21662. [PMID: 31549705 DOI: 10.1039/c9cp04917g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The comparison of the ground-state reactivity of anthocyanins and aurone model compounds (i.e. with and without the furano bridge) has shown that the kinetic paradigm does not depend on the bridge but only on the hydroxyl substituent pattern, independently of the presence of the bridge: (i) bell shaped kinetics for those with two hydroxyl substituents in position 4' and 7, and (ii) four distinct kinetic steps for the mono substituted compounds with a hydroxyl in position 4'. The excited state proton transfer (ESPT) properties of these compounds were also investigated using steady-state and time-resolved spectroscopic techniques. It was found that the ESPT efficiency is significantly higher for the bridged compounds. Interestingly, pH-dependent steady-state fluorescence emission experiments show that in 4',7-dihydroxyfuranoflavylium the hydroxyl group in position 7 is the more acidic one in the excited state, while 1H NMR titration curves indicate a higher acidity constant in the ground state for the proton at the hydroxyl group in position 4'. Differently, the fluorescence emission spectrum of the quinoidal base deprotonated at position 7 is only observed upon excitation of the flavylium cation while the one from the base deprotonated at 4' is observed upon direct excitation.
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Affiliation(s)
- Alfonso Alejo-Armijo
- LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal.
| | - Nuno Basílio
- LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal.
| | - Adilson A Freitas
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, Lisboa 1048-001, Portugal
| | - António L Maçanita
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, Lisboa 1048-001, Portugal
| | - João C Lima
- LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal.
| | - A Jorge Parola
- LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal.
| | - Fernando Pina
- LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal.
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4
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Awasthi AA, Singh PK. Proton Transfer Reaction Dynamics of Pyranine in DMSO/Water Mixtures. Chemphyschem 2017; 19:198-207. [DOI: 10.1002/cphc.201701133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Indexed: 11/09/2022]
Affiliation(s)
| | - Prabhat K. Singh
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Trombay Mumbai- 400 085 India
- Homi Bhabha National Institute; Training School Complex; Anushaktinagar Mumbai 400094 India
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5
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Ma Y, Hou C, Li D, Huo D. The effect and evidence of ethanol content on the stability of anthocyanins from purple‐fleshed sweet potato. J FOOD PROCESS PRES 2017. [DOI: 10.1111/jfpp.13484] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yi Ma
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of BioengineeringChongqing University Chongqing 400044 P.R. China
- Liquor Making Biology Technology and Application of Key Laboratory of Sichuan Province, College of BioengineeringSichuan University of Science and Engineering Zigong 643000 P.R. China
| | - Chang‐Jun Hou
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of BioengineeringChongqing University Chongqing 400044 P.R. China
| | - Dan Li
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of BioengineeringChongqing University Chongqing 400044 P.R. China
| | - Dan‐Qun Huo
- Key Laboratory of Biorheology Science and Technology, Ministry of Education, College of BioengineeringChongqing University Chongqing 400044 P.R. China
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Roy B, Hazra P. Dynamics of different steps of the photopyrolytic cycle of an eminent anticancer drug topotecan inside biocompatible lyotropic liquid crystalline systems. RSC Adv 2017. [DOI: 10.1039/c6ra25200a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dynamics of different steps of photopyrolytic processes of an eminent anticancer drug topotecan have been investigated inside different lyotropic liquid crystalline systems.
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Affiliation(s)
- Bibhisan Roy
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER)
- Pune
- India
| | - Partha Hazra
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER)
- Pune
- India
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7
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Vester M, Grueter A, Finkler B, Becker R, Jung G. Biexponential photon antibunching: recombination kinetics within the Förster-cycle in DMSO. Phys Chem Chem Phys 2016; 18:10281-8. [PMID: 27020473 DOI: 10.1039/c6cp00718j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Time-resolved experiments with pulsed-laser excitation are the standard approach to map the dynamic evolution of excited states, but ground-state kinetics remain hidden or require pump-dump-probe schemes. Here, we exploit the so-called photon antibunching, a purely quantum-optical effect related to single molecule detection to assess the rate constants for a chemical reaction in the electronic ground state. The measurement of the second-order correlation function g((2)), i.e. the evaluation of inter-photon arrival times, is applied to the reprotonation in a Förster-cycle. We find that the antibunching of three different photoacids in the aprotic solvent DMSO significantly differs from the behavior in water. The longer decay constant of the biexponential antibunching tl is linked to the bimolecular reprotonation kinetics of the fully separated ion-pair, independent of the acidic additives. The value of the corresponding bimolecular rate constant, kp = 4 × 10(9) M(-1) s(-1), indicates diffusion-controlled reprotonation. The analysis of tl also allows for the extraction of the separation yield of proton and the conjugated base after excitation and amounts to approximately 15%. The shorter time component ts is connected to the decay of the solvent-separated ion pair. The associated time constant for geminate reprotonation is approximately 3 ± 1 ns in agreement with independent tcspc experiments. These experiments verify that the transfer of quantum-optical experiments to problems in chemistry enables mechanistic conclusions which are hardly accessible by other methods.
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Affiliation(s)
- Michael Vester
- Biophysical Chemistry, Saarland University, 66123 Saarbrücken, Germany.
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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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Kasai Y, Yoshida N, Nakano H. Theoretical analysis of co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture. J Chem Phys 2015; 142:204103. [PMID: 26026430 DOI: 10.1063/1.4921432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture was examined using the reference interaction-site model self-consistent field theory. The free energy profiles of the proton transfer reaction of glycine between the carboxyl oxygen and amino nitrogen were computed in a water-acetonitrile mixture solvent at various molar fractions. Two types of reactions, the intramolecular proton transfer and water-mediated proton transfer, were considered. In both types of the reactions, a similar tendency was observed. In the pure water solvent, the zwitterionic form, where the carboxyl oxygen is deprotonated while the amino nitrogen is protonated, is more stable than the neutral form. The reaction free energy is -10.6 kcal mol(-1). On the other hand, in the pure acetonitrile solvent, glycine takes only the neutral form. The reaction free energy from the neutral to zwitterionic form gradually increases with increasing acetonitrile concentration, and in an equally mixed solvent, the zwitterionic and neutral forms are almost isoenergetic, with a difference of only 0.3 kcal mol(-1). The free energy component analysis based on the thermodynamic cycle of the reaction also revealed that the free energy change of the neutral form is insensitive to the change of solvent environment but the zwitterionic form shows drastic changes. In particular, the excess chemical potential, one of the components of the solvation free energy, is dominant and contributes to the stabilization of the zwitterionic form.
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Affiliation(s)
- Yukako Kasai
- Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Norio Yoshida
- Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Haruyuki Nakano
- Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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10
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Basílio N, Laia CAT, Pina F. Excited-state proton transfer in confined medium. 4-methyl-7-hydroxyflavylium and β-naphthol incorporated in cucurbit[7]uril. J Phys Chem B 2014; 119:2749-57. [PMID: 25438065 DOI: 10.1021/jp511351w] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Excited-state proton transfer (ESPT) was studied by fluorescent emission using a mathematical model recast from the Weller theory. The titration curves can be fitted with three parameters: pK(a) (acidity constant of the ground sate), pK(ap)* (apparent acidity constant of the excited state), and η(A*), the efficiency of excited base formation from the excited acid. β-Naphthol and 4-metyhl-7-hydroxyflavylium were studied in aqueous solution and upon incorporation in cucurbit[7]uril. For all the compounds studied the interaction with the host leads to 1:1 adducts and the ground-state pK(a) increases upon incorporation. Whereas the ESPT of 4-methyl-7-hydroxyflavylium practically does not change in the presence of the host, in the case of β-naphthol it is prevented and the fluorescence emission titration curves are coincident with those taken by absorption. The position of the guest inside the host was investigated by NMR experiments and seems to determine the efficiency of the ESPT. The ESPT decreases for the guest, exhibiting a great protection of the phenol to the bulk water interaction.
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Affiliation(s)
- Nuno Basílio
- REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Monte de Caparica, Portugal
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Kuchlyan J, Banik D, Roy A, Kundu N, Sarkar N. Excited-State Proton Transfer Dynamics of Firefly’s Chromophore D-Luciferin in DMSO–Water Binary Mixture. J Phys Chem B 2014; 118:13946-53. [PMID: 25415652 DOI: 10.1021/jp510389d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Jagannath Kuchlyan
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India
| | - Debasis Banik
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India
| | - Arpita Roy
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India
| | - Niloy Kundu
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India
| | - Nilmoni Sarkar
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India
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12
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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: 11] [Impact Index Per Article: 1.1] [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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Freitas AA, Quina FH, Maçanita AAL. Femtosecond and temperature-dependent picosecond dynamics of ultrafast excited-state proton transfer in water-dioxane mixtures. J Phys Chem A 2014; 118:10448-55. [PMID: 24925753 DOI: 10.1021/jp504189m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Synthetic flavylium salts like the 7-hydroxy-4-methylflavylium (HMF) cation have been used as prototypes to study the chemistry and photochemistry of anthocyanins, the major group of water-soluble pigments in the plant kingdom. In this work, a combination of fluorescence upconversion with femtosecond time resolution and time-correlated single photon counting (TCSPC) with picosecond time resolution have been employed to investigate in details the excited-state proton transfer (ESPT) of HMF in water and in binary water/1,4-dioxane mixtures. TCSPC measurements as a function of temperature provide activation parameters for all of the individual rate constants involved in the proton transfer, including those for dissociation and recombination of the geminate excited base-proton pair (A*···H(+)) that can be detected in the water/dioxane mixtures (but not in water). Unlike the other rate constants, the deprotonation rate constant kd shows a non-Arrhenius dependence on temperature in both water and water/dioxane mixtures. At low temperatures kd is close to the dielectric relaxation rate of the solvent with a barrier of ca. 8 kJ mol(-1), suggesting that the solvent reorganization is the rate-limiting step. At higher temperatures (>30 °C) the proton transfer process is nearly barrierless and solvent-dependent. Fluorescence upconversion results in H2O, D2O, and water/dioxane mixtures confirm the two-step model for the ESPT of HMF and provide additional details of the early events prior to the onset of proton transfer, attributed to conformational relaxation and solvent reaccommodation around the initially formed excited state. The results are consistent with DFT calculations that indicate that charge redistribution occurs after rather than prior to the onset of the ESPT process.
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Affiliation(s)
- Adilson A Freitas
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , 1649-004 Lisbon, Portugal
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Gavara R, Leydet Y, Petrov V, Pina F. Photochemistry of 2-(4-hydroxystyryl)-1-naphthopyrylium. Photochem Photobiol Sci 2013; 11:1691-9. [PMID: 22797713 DOI: 10.1039/c2pp25104c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new photochromic system based on 2-(4-hydroxystyryl)-1-naphthopyrylium encompasses the properties of the previously described naphthoflavylium and styrylflavylium systems. The photoproduct exhibits a colour deep in hue and is red shifted in comparison with the equivalent flavylium system. Reaction of 2-hydroxy-1-naphthaldehyde with p-hydroxystyrylmethylketone in acetic acid in the presence of tetrafluoroboric acid and acetic anhydride as catalysts leads to a mixture of two compounds: the photochromic 2-(4-hydroxystyryl)-1-naphthopyrylium and a second product 2-(4-acetoxystyryl)-1-naphthopyrylium resulting from the acetylation by acetic anhydride of the former. In acidic medium and at room temperature the hydrolysis of the acetoxy derivative leads to the 2-(4-hydroxystyryl)-1-naphthopyrylium, in circa 2 days, [HCl] = 0.25 M. The pH dependent chemical reactions taking place with 2-(4-hydroxystyryl)-1-naphthopyrylium were determined by UV-Vis, stooped flow, flash photolysis and (1)H NMR and follow the same general pattern of flavylium derivatives. In order to rationalize the photochromism, an energy level diagram summarizing all the equilibrium and rate constants of the network was drawn.
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Affiliation(s)
- Raquel Gavara
- REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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15
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Dynamics and prototropic reactivity of electronically excited states in simple surfactant aggregates. Curr Opin Colloid Interface Sci 2013. [DOI: 10.1016/j.cocis.2012.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Spies C, Finkler B, Acar N, Jung G. Solvatochromism of pyranine-derived photoacids. Phys Chem Chem Phys 2013; 15:19893-905. [DOI: 10.1039/c3cp53082e] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Freitas AA, Maçanita AAL, Quina FH. Improved analysis of excited state proton transfer kinetics by the combination of standard and convolution methods. Photochem Photobiol Sci 2013; 12:902-10. [DOI: 10.1039/c3pp25445c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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