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Golczak A, Prukała D, Sikorska E, Gierszewski M, Cherkas V, Kwiatek D, Kubiak A, Varma N, Pędziński T, Murphree S, Cibulka R, Mrówczyńska L, Kolanowski JL, Sikorski M. Tetramethylalloxazines as efficient singlet oxygen photosensitizers and potential redox-sensitive agents. Sci Rep 2023; 13:13426. [PMID: 37591918 PMCID: PMC10435492 DOI: 10.1038/s41598-023-40536-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 08/12/2023] [Indexed: 08/19/2023] Open
Abstract
Tetramethylalloxazines (TMeAll) have been found to have a high quantum yield of singlet oxygen generation when used as photosensitizers. Their electronic structure and transition energies (S0 → Si, S0 → Ti, T1 → Ti) were calculated using DFT and TD-DFT methods and compared to experimental absorption spectra. Generally, TMeAll display an energy diagram similar to other derivatives belonging to the alloxazine class of compounds, namely π,π* transitions are accompanied by closely located n,π* transitions. Photophysical data such as quantum yields of fluorescence, fluorescence lifetimes, and nonradiative rate constants were also studied in methanol (MeOH), acetonitrile (ACN), and 1,2-dichloroethane (DCE). The transient absorption spectra were also analyzed. To assess cytotoxicity of new compounds, a hemolytic assay was performed using human red blood cells (RBC) in vitro. Subsequently, fluorescence lifetime imaging experiments (FLIM) were performed on RBC under physiological and oxidative stress conditions alone or in the presence of TMeAll allowing for pinpointing changes caused by those compounds on the intracellular environment of these cells.
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Affiliation(s)
- Anna Golczak
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland
| | - Dorota Prukała
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland
| | - Ewa Sikorska
- Poznań University of Economics and Business, Al. Niepodległości 10, 61-875, Poznan, Poland
| | - Mateusz Gierszewski
- Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614, Poznan, Poland
| | - Volodymyr Cherkas
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Dorota Kwiatek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Adam Kubiak
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland
| | - Naisargi Varma
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland
| | - Tomasz Pędziński
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland
| | - Shaun Murphree
- Department of Chemistry, Allegheny College, 520 N. Main Street, Meadville, PA, USA
| | - Radek Cibulka
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technicka 5, 16628, Prague 6, Czech Republic.
| | - Lucyna Mrówczyńska
- Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznan, Poland.
| | - Jacek Lukasz Kolanowski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.
| | - Marek Sikorski
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznan, Poland.
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2
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Curtolo F, Arantes GM. Molecular properties and tautomeric equilibria of isolated flavins. J Comput Chem 2022; 43:1561-1572. [PMID: 35778728 DOI: 10.1002/jcc.26957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/09/2022] [Indexed: 11/05/2022]
Abstract
Flavins are employed as redox cofactors and chromophores in a plethora of flavoenzymes. Their versatility is an outcome of intrinsic molecular properties of the isoalloxazine ring modulated by the protein scaffold and surrounding solvent. Thus, an investigation of isolated flavins with high-level electronic-structure methods and with error assessment of the calculated properties will contribute to building better models of flavin reactivity. Here, we benchmarked ground-state properties such as electron affinity, gas-phase basicity, dipole moment, torsion energy, and tautomer stability for lumiflavins in all biologically relevant oxidation and charge states. Overall, multiconfigurational effects are small and chemical accuracy is achieved by coupled-cluster treatments of energetic properties. Augmented basis sets and extrapolations to the complete basis-set limit are necessary for consistent agreement with experimental energetics. Among DFT functionals tested, M06-2X shows the best performance for most properties, except gas-phase basicity, in which M06 and CAM-B3LYP perform better. Moreover, dipole moments of radical flavins show large deviations for all functionals studied. Tautomers with noncanonical protonation states are significantly populated at normal temperatures, adding to the complexity of modeling flavins. These results will guide future computational studies of flavoproteins and flavin chemistry by indicating the limitations of electronic-structure methodologies and the contributions of multiple tautomeric states.
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Affiliation(s)
- Felipe Curtolo
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Guilherme M Arantes
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
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3
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Theoretical modeling of optical spectra of N(1) and N(10) substituted lumichrome derivatives. ACTA CHIMICA SLOVACA 2021. [DOI: 10.2478/acs-2020-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
A systematic study of (7,8-dimethylated) alloxazine, isoalloxazine, and their derivatives with substituted N(1) and N(10) positions was conducted using the density functional theory. The main aim of this work was the direct investigation of substituent effect on the molecular structure. Furthermore, HOMED aromaticity indices were calculated to describe the scope of the geometry changes. Frontier molecular orbitals of reference alloxazine, isoalloxazine and lumichrome derivatives were discussed by means of changes in their shape and energy levels. Photophysical properties were analyzed by determination of optical transition energies using the TD-DFT method. Obtained results were compared with previously published experimental data.
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4
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Su D, Kabir MP, Orozco-Gonzalez Y, Gozem S, Gadda G. Fluorescence Properties of Flavin Semiquinone Radicals in Nitronate Monooxygenase. Chembiochem 2019; 20:1646-1652. [PMID: 30748074 DOI: 10.1002/cbic.201900016] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Indexed: 11/09/2022]
Abstract
Fluorescent cofactors like flavins can be exploited to probe their local environment with spatial and temporal resolution. Although the fluorescence properties of the oxidized and two-electron-reduced states of flavins have been studied extensively, this is not the case for the one-electron-reduced state. Both the neutral and anionic semiquinones have proven particularly challenging to examine, as they are unstable in solution and are transient, short-lived species in many catalytic cycles. Here, we report that the nitronate monooxygenase (NMO) from Pseudomonas aeruginosa PAO1 is capable of stabilizing both semiquinone forms anaerobically for hours, thus enabling us to study their spectroscopy in a constant protein environment. We found that in the active site of NMO, the anionic semiquinone exhibits no fluorescence, whereas the neutral semiquinone radical shows a relatively strong fluorescence, with a behavior that violates the Kasha-Vavilov rule. These fluorescence properties are discussed in the context of time-dependent density functional theory calculations, which reveal low-lying dark states in both systems.
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Affiliation(s)
- Dan Su
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Mohammad Pabel Kabir
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Yoelvis Orozco-Gonzalez
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Samer Gozem
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA.,Department of Biology, Georgia State University, 100 Piedmond Ave., Atlanta, GA, 30303, USA.,Center for Diagnostics and Therapeutics, Georgia State University, P.O. Box 5090, Atlanta, GA, 30303, USA.,Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, 30302, USA
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5
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Kabir MP, Orozco-Gonzalez Y, Gozem S. Electronic spectra of flavin in different redox and protonation states: a computational perspective on the effect of the electrostatic environment. Phys Chem Chem Phys 2019; 21:16526-16537. [DOI: 10.1039/c9cp02230a] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This study discusses how UV/vis absorption spectra of flavin in different redox and protonation states are shifted by the nearby electrostatic microenvironment.
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Affiliation(s)
| | | | - Samer Gozem
- Department of Chemistry
- Georgia State University
- Atlanta
- USA
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6
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Reiffers A, Torres Ziegenbein C, Engelhardt A, Kühnemuth R, Gilch P, Czekelius C. Impact of Mono-Fluorination on the Photophysics of the Flavin Chromophore. Photochem Photobiol 2018; 94:667-676. [DOI: 10.1111/php.12921] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/25/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Anna Reiffers
- Institut für Physikalische Chemie; Heinrich-Heine-Universität Düsseldorf; Düsseldorf Germany
| | | | - Alyn Engelhardt
- Institut für Physikalische Chemie; Heinrich-Heine-Universität Düsseldorf; Düsseldorf Germany
| | - Ralf Kühnemuth
- Institut für Physikalische Chemie; Heinrich-Heine-Universität Düsseldorf; Düsseldorf Germany
| | - Peter Gilch
- Institut für Physikalische Chemie; Heinrich-Heine-Universität Düsseldorf; Düsseldorf Germany
| | - Constantin Czekelius
- Institut für Organische Chemie und Makromolekulare Chemie; Heinrich-Heine-Universität Düsseldorf; Düsseldorf Germany
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7
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Daidone I, Amadei A, Aschi M, Zanetti-Polzi L. On the nature of solvatochromic effect: The riboflavin absorption spectrum as a case study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 192:451-457. [PMID: 29212059 DOI: 10.1016/j.saa.2017.11.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/27/2017] [Accepted: 11/14/2017] [Indexed: 06/07/2023]
Abstract
We present here the calculation of the absorption spectrum of riboflavin in acetonitrile and dimethyl sulfoxide using a hybrid quantum/classical approach, namely the perturbed matrix method, based on quantum mechanical calculations and molecular dynamics simulations. The calculated spectra are compared to the absorption spectrum of riboflavin previously calculated in water and to the experimental spectra obtained in all three solvents. The experimentally observed variations in the absorption spectra upon change of the solvent environment are well reproduced by the calculated spectra. In addition, the nature of the excited states of riboflavin interacting with different solvents is investigated, showing that environment effects determine a recombination of the gas-phase electronic states and that such a recombination is strongly affected by the polarity of the solvent inducing significant changes in the absorption spectra.
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Affiliation(s)
- Isabella Daidone
- Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio (Coppito 1), L'Aquila 67010, Italy
| | - Andrea Amadei
- Department of Chemical and Technological Sciences, University of Rome "Tor Vergata", Via della Ricerca Scientifica, 00185 Rome, Italy
| | - Massimiliano Aschi
- Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio (Coppito 1), L'Aquila 67010, Italy
| | - Laura Zanetti-Polzi
- Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio (Coppito 1), L'Aquila 67010, Italy.
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8
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Ji X, Wu RT, Long L, Guo C, Khashab NM, Huang F, Sessler JL. Physical Removal of Anions from Aqueous Media by Means of a Macrocycle-Containing Polymeric Network. J Am Chem Soc 2018; 140:2777-2780. [PMID: 29437394 DOI: 10.1021/jacs.7b13656] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reported here is a hydrogel-forming polymer network that contains a water-soluble tetracationic macrocycle. Upon immersion of this polymer network in aqueous solutions containing various inorganic and organic salts, changes in the physical properties are observed that are consistent with absorption of the constituent anions into the polymer network. This absorption is ascribed to host-guest interactions involving the tetracationic macrocyclic receptor. Removal of the anions may then be achieved by lifting the resulting hydrogels out of the aqueous phase. Treating the anion-containing hydrogels with dilute HCl leads to the protonation-induced release of the bound anions. This allows the hydrogels to be recycled for reuse. The present polymer network thus provides a potentially attractive approach to removing undesired anions from aqueous environments.
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Affiliation(s)
- Xiaofan Ji
- Department of Chemistry, 105 East 24th Street, Stop A5300, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Ren-Tsung Wu
- Department of Chemistry, 105 East 24th Street, Stop A5300, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Lingliang Long
- Department of Chemistry, 105 East 24th Street, Stop A5300, The University of Texas at Austin , Austin, Texas 78712, United States.,School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang, Jiangsu 212013, P. R. China
| | - Chenxing Guo
- Department of Chemistry, 105 East 24th Street, Stop A5300, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Niveen M Khashab
- Smart Hybrid Materials (SHMs) Laboratory, Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology , Thuwal 23955, Saudi Arabia
| | - Feihe Huang
- State Key Laboratory of Chemical Engineering, Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China
| | - Jonathan L Sessler
- Department of Chemistry, 105 East 24th Street, Stop A5300, The University of Texas at Austin , Austin, Texas 78712, United States.,Center for Supramolecular Chemistry and Catalysis, Shanghai University , Shanghai 200444, China
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9
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10
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Domratcheva T, Fedorov R, Schlichting I. Analysis of the Primary Photocycle Reactions Occurring in the Light, Oxygen, and Voltage Blue-Light Receptor by Multiconfigurational Quantum-Chemical Methods. J Chem Theory Comput 2015; 2:1565-74. [PMID: 26627027 DOI: 10.1021/ct0600114] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photocycle reactions occurring between the flavin mononucleotide cofactor and the reactive cysteine residue in the blue-light photoreceptor domain light, oxygen, and voltage (LOV) were modeled for a system consisting of lumiflavin and thiomethanol. The electronic structure and energies of the reactive species were estimated using the CASSCF and MCQDPT2 quantum-chemical methods. The reaction pathway for the S-C4a covalent adduct formation in the triplet state was determined. Concerted electron and proton transfer from the thiol to the flavin in the triplet electronic state results in a biradical complex that is, however, unstable because its structure corresponds to a triplet-singlet crossing. The covalent adduct dissociation in the ground electronic state is a reverse of the photoreaction proceeding via a single energy barrier for hydrogen transfer. Thus, both photo- and dark reactions were found to be single-step chemical transformations occurring without stable intermediates. The photoreaction yielding the S-C4a covalent adduct is an intrinsic property of the isoalloxazine-thiol complex in the specific geometry arranged by the protein in LOV. The S-C4a covalent adduct between lumiflavin and thiomethanol is rather stable implying that in LOV its dissociation is facilitated by the protein.
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Affiliation(s)
- Tatiana Domratcheva
- Max-Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Roman Fedorov
- Max-Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Ilme Schlichting
- Max-Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Jahnstrasse 29, 69120 Heidelberg, Germany
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11
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Falklöf O, Durbeej B, Norman P. Inter-Excited-State Phosphorescence in the Four-Component Relativistic Kohn–Sham Approximation: A Case Study on Lumiflavin. J Phys Chem A 2015; 119:11911-21. [DOI: 10.1021/acs.jpca.5b08908] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Olle Falklöf
- Division of Theoretical
Chemistry, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | - Bo Durbeej
- Division of Theoretical
Chemistry, IFM, Linköping University, SE-581 83 Linköping, Sweden
| | - Patrick Norman
- Division of Theoretical
Chemistry, IFM, Linköping University, SE-581 83 Linköping, Sweden
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12
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Spectroscopy and Photophysics of Monomethyl-Substituted Derivatives of 5-Deazaalloxazine and 10-Ethyl-5-Deaza-Isoalloxazine. J Fluoresc 2013; 24:505-21. [PMID: 24272639 DOI: 10.1007/s10895-013-1320-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Accepted: 11/07/2013] [Indexed: 11/27/2022]
Abstract
Steady-state and time-resolved spectra were used to describe the singlet and triplet states of 8-methyl-5-deazaalloxazine (8-Me-5-DAll), 9-methyl-5-deazaalloxazine (9-Me-5-DAll) and 10-ethyl-5-deaza-isoalloxazine (10-Et-5-DIAll). Solvatochromic properties were described using different polarity scales, including Δf and the four-parameter scale proposed by Catalán. The results indicate that the Catalán scale shows a strong influence of solvent acidity (hydrogen-bond donating ability) on the emission properties of 8-Me-5-DAll and 9-Me-5-DAll. These results indicate the importance of intermolecular solute-solvent hydrogen-bonding interactions in the excited state of these compounds. Contrary to deazaalloxazines, solvent acidity affects the absorption spectra of 10-Et-5-DIAll. Fluorescence lifetimes and quantum yields and also transient absorption spectra were determined for all of the compounds studied. Electronic structure and S(0)-S(i), S(0)-T(i ), T(1)-T(i) transitions energies and oscillator strengths were calculated using the TD-DFT methods. Theoretical calculations were compared to experimental data.
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13
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Vdovin A, Slenczka A, Dick B. Electronic spectroscopy of lumiflavin in superfluid helium nanodroplets. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Quick M, Weigel A, Ernsting NP. Fluorescence following Excited-State Protonation of Riboflavin at N(5). J Phys Chem B 2013; 117:5441-7. [DOI: 10.1021/jp312571d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Martin Quick
- Department
of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - Alexander Weigel
- Department
of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - Nikolaus P. Ernsting
- Department
of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
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15
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Penzkofer A. Photoluminescence behavior of riboflavin and lumiflavin in liquid solutions and solid films. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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16
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Wu M, Eriksson LA. Absorption spectra of riboflavin--a difficult case for computational chemistry. J Phys Chem A 2011; 114:10234-42. [PMID: 20718485 DOI: 10.1021/jp104127r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Computing accurate absorption spectra of riboflavin (RBF) has proven a difficult task for computational chemistry. Time-dependent density functional theory have herein been employed using a wide range of recent range-separated and hybrid meta functionals to investigate ultraviolet and visible spectra of RBF to determine if any progress has been made through recent developments. It is concluded that B3LYP and PBE0 perform the best throughout the entire test set. However, since all methods deviate from experimental results by at least 40 nm when computing the spectra in vacuum, two approaches to describe aqueous solution are implemented together with the MPWB1K, B3LYP, and PBE0 functionals: implicitly using integral equation formulation of the polarized continuum model (minor improvement) and explicitly through molecular dynamics (MD) simulations of the molecule embedded in a water cluster whereafter snapshots of RBF-water clusters are extracted and time-dependent density functional theory calculations performed. The resulting averaged spectra from the MD-simulated clusters show a constant blue-shift for all peaks by ∼20 nm compared to experimental data at the TD-B3LYP/6-31+G(d,p) level.
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Affiliation(s)
- Min Wu
- School of Chemistry, National University of Ireland, Galway, Ireland
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17
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18
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pH dependence of the absorption and emission behaviour of lumiflavin in aqueous solution. J Photochem Photobiol A Chem 2010. [DOI: 10.1016/j.jphotochem.2010.08.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Sikorski M, Prukała D, Insińska-Rak M, Khmelinskii I, Worrall DR, Williams SL, Hernando J, Bourdelande JL, Koput J, Sikorska E. Spectroscopy and photophysics of dimethyl-substituted alloxazines. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.07.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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21
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Sikorska E, Khmelinskii I, Hoffmann M, Machado IF, Ferreira LFV, Dobek K, Karolczak J, Krawczyk A, Insińska-Rak M, Sikorski M. Ground- and Excited-State Double Proton Transfer in Lumichrome/Acetic Acid System: Theoretical and Experimental Approach. J Phys Chem A 2005; 109:11707-14. [PMID: 16366620 DOI: 10.1021/jp053951d] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Experimental time-resolved spectral and photon counting kinetic results confirm formation of an isoalloxazinic excited state via excited-state double proton transfer (ESDPT) catalyzed by a carboxylic acid molecule that forms a hydrogen-bond complex with the parent alloxazine molecule. This isoalloxazinic tautomer manifests itself as a distinct long-lived emissive species formed only in such alloxazine derivatives that were not substituted at the N1 nitrogen atom, being a product of the excited-state reaction occurring from the alloxazinic excited state. Theoretical calculations support the idea that the ESDPT occurs by the concerted mechanism. The calculated activation barrier in the excited state is much lower than the same barrier in the ground state and even disappears for the HOMO-1 to LUMO excitation, which explains the fact that the reaction takes place in the excited-state only. The reaction rate estimated from the emission kinetics is ca. 1.4 x 10(8) dm3 mol(-1) s(-1) in ethanolic solutions of lumichrome with added acetic acid.
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Affiliation(s)
- Ewa Sikorska
- Faculty of Commodity Science, Poznań University of Economics, al. Niepodleglości 10, 60-967 Poznań, Poland
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23
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Sikorska E, Khmelinskii I, Komasa A, Koput J, Ferreira LF, Herance JR, Bourdelande JL, Williams SL, Worrall DR, Insińska-Rak M, Sikorski M. Spectroscopy and photophysics of flavin related compounds: Riboflavin and iso-(6,7)-riboflavin. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2005.03.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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24
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Sikorska E, Herance JR, Bourdelande JL, Khmelinskii IV, Williams SL, Worrall DR, Nowacka G, Komasa A, Sikorski M. Spectroscopy and photophysics of flavin-related compounds: 3-ethyl-lumiflavin. J Photochem Photobiol A Chem 2005. [DOI: 10.1016/j.jphotochem.2004.08.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Insińska-Rak M, Sikorska E, Herance JR, Bourdelande JL, Khmelinskii IV, Kubicki M, Prukała W, Machado IF, Komasa A, Ferreira LFV, Sikorski M. Spectroscopy and photophysics of flavin-related compounds: 3-benzyl-lumiflavin. Photochem Photobiol Sci 2005; 4:463-8. [PMID: 15920630 DOI: 10.1039/b503898g] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular structure, spectroscopic and photophysical data for the singlet state of 3-benzyl-lumiflavin in different solvents are presented. Theoretical studies concerning singlet-singlet and triplet-triplet excitation energies were carried out using time-dependent density functional theory (TD-DFT) calculations. These predictions are in good agreement with the experimental results, which reflect the solvent interactions. All the observable singlet-singlet transitions have pi-pi* character. The title compound appears to be an efficient sensitizer of the production of singlet oxygen (phi(Delta)= 0.53). The crystal structure of 3-benzyl-lumiflavin is also presented, along with its solid-state photophysical data.
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Sikorska E, Khmelinskii IV, Williams SL, Worrall DR, Herance JR, Bourdelande JL, Koput J, Sikorski M. Spectroscopy and photophysics of 6,7-dimethyl-alloxazine: experimental and theoretical study. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2004.04.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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