1
|
Poljak M, Wohlrábová L, Palao E, Nociarová J, Míšek J, Slanina T, Klán P. Chalcogen-based ratiometric reversible BODIPY redox sensors for the determination of enantioselective methionine sulfoxide reductase activity. Chem Commun (Camb) 2022; 58:6389-6392. [PMID: 35543358 DOI: 10.1039/d2cc02016e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many serious diseases are associated with degenerative changes caused by oxidative stress triggered by elevated concentrations of reactive oxygen species (ROS) in cells. Therefore, the development of suitable probes for monitoring such processes is of great importance. Here, we introduce a series of sulfur- and selenium-substituted BODIPY derivatives as reversible redox sensors for ROS and enzymatic redox processes. Significant differences in emission maxima and fluorescence quantum yields between the reduced and oxidized forms make them excellent ratiometric turn-on/off probes. Installation of polar sulfonate groups improved their aqueous solubility while retaining their sensing properties, which allowed the probes to monitor the enzymatic activity of enantioselective methionine sulfoxide reductase.
Collapse
Affiliation(s)
- Michal Poljak
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic. .,RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Lucie Wohlrábová
- Institute of Organic Chemistry and Biochemistry, Flemingovo náměstí 542, 160 00 Prague, Czech Republic.
| | - Eduardo Palao
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic. .,RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Jela Nociarová
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic. .,RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Jiří Míšek
- Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843 Prague 2, Czech Republic
| | - Tomáš Slanina
- Institute of Organic Chemistry and Biochemistry, Flemingovo náměstí 542, 160 00 Prague, Czech Republic.
| | - Petr Klán
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic. .,RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| |
Collapse
|
2
|
Tojo S, Fujitsuka M, Majima T. Structures of 4-substituted thioanisole radical cations studied by time-resolved resonance Raman spectroscopy during pulse radiolysis and theoretical calculations. RSC Adv 2016. [DOI: 10.1039/c6ra21460f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The structures of 4-substituted thioanisole radical cations were studied by time-resolved resonance Raman spectroscopy during pulse radiolysis and DFT calculation, indicating importance of charge and spin distributions toward the dimerization.
Collapse
Affiliation(s)
- Sachiko Tojo
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| | - Mamoru Fujitsuka
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| | - Tetsuro Majima
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| |
Collapse
|
3
|
Prasanthkumar KP, Suresh CH, Aravindakumar CT. Oxidation reactions of 2-thiouracil: a theoretical and pulse radiolysis study. J Phys Chem A 2012; 116:10712-20. [PMID: 23061532 DOI: 10.1021/jp303808r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of hydroxyl radical ((•)OH) with the nucleic acid base analogue 2-thiouracil (1) has been studied by pulse radiolysis experiments and DFT. The generic intermediate radicals feasible for the (•)OH reactions with 1, namely, one electron oxidation product (1(•+)), (•)OH-adducts (3(•), 4(•), and 5(•)), and H-abstracted radicals (6(•) and 7(•)), were characterized by interpreting their electronic and structural properties along with calculated energetics and UV-vis spectra. Pulse radiolysis experiments showed that the transient formed in the reaction of (•)OH with 1 in water at pH 6.5 has λ(max) at 430 nm. A bimolecular rate constant, k(2) of 9.6 × 10(9) M(-1) s(-1), is determined for this reaction via competition kinetics with 2-propanol. The experiments suggested that the transient species could be a dimer radical cation 2(•+), formed by the reaction of 1 with the radical cation 1(•+). For this reaction, an equilibrium constant of 4.7 × 10(3) M(-1) was determined. The transient formed in the reaction of 1 with pulse radiolytically produced Br(2)(•-) at pH 6.5 as well as Cl(2)(•-) at pH 1 has also produced λ(max) at 430 nm and suggested the formation of 2(•+). The calculated UV-vis spectra of the transient species (1(•+), 3(•), 4(•), 5(•), 6(•), and 7(•)) showed no resemblance to the experimental spectra, while that of 2(•+) (λ(max) = 420 nm) agreed well with the experimental value and thus confirmed the formation of 2(•+). The 420 nm peak was due to σ → σ* electronic excitation centered on a 2-center-3-electron (2c-3e) sulfur-sulfur bond [-S∴S-]. 2(•+) is the first reported example of a dimer radical cation in a pyrimidine heterocyclic system. Further, 5-C and 6-C substituted (substituents are -F, -Cl, -NH(2), -N(CH(3))(2), -OCH(3), -CF(3), -CH(3), -CH(2)CH(3), n-propyl, phenyl, and benzyl) and 5,6-disubstituted 2-thiouracil systems have been characterized by DFT and found that the reaction (1 + 1(•+) → 2(•+)) is exergonic (1.12-13.63 kcal/mol) for many of them.
Collapse
Affiliation(s)
- K P Prasanthkumar
- School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, India
| | | | | |
Collapse
|
4
|
Lanzalunga O, Lapi A. Recent photo- and radiation chemical studies of sulfur radical cations. J Sulphur Chem 2011. [DOI: 10.1080/17415993.2011.619536] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Osvaldo Lanzalunga
- a Dipartimento di Chimica and IMC-CNR, Sezione Meccanismi di Reazione , Università “La Sapienza” , P.le A. Moro, 5 I-00185 , Rome , Italy
| | - Andrea Lapi
- a Dipartimento di Chimica and IMC-CNR, Sezione Meccanismi di Reazione , Università “La Sapienza” , P.le A. Moro, 5 I-00185 , Rome , Italy
| |
Collapse
|
5
|
Shirdhonkar M, Mohan H, Maity D, Rao B. Oxidation of phenyl vinyl sulphide and phenyl vinyl sulphoxide in aqueous solution: A pulse radiolysis and theoretical study. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.07.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
6
|
Cardey B, Enescu M. Cysteine Oxidation by the Superoxide Radical: A Theoretical Study. Chemphyschem 2009; 10:1642-8. [DOI: 10.1002/cphc.200900010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
7
|
Samori S, Fujitsuka M, Majima T. Properties of Excited Radical Cations of Substituted Oligothiophenes. J Phys Chem A 2008; 112:11312-8. [DOI: 10.1021/jp804369e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Shingo Samori
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Mamoru Fujitsuka
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Tetsuro Majima
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| |
Collapse
|
8
|
Priyadarsini KI, Mishra B. Radical cations of some water-soluble organoselenium compounds: Insights from pulse radiolysis studies. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2008.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
9
|
|
10
|
Shirdhonkar M, Mohan H, Maity D, Rao B. Oxidation of phenyl trifluoromethyl sulphide: A pulse radiolysis and theoretical study. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2007.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
11
|
Mishra B, Kumbhare LB, Jain VK, Priyadarsini KI. Pulse Radiolysis Studies on Reactions of Hydroxyl Radicals with Selenocystine Derivatives. J Phys Chem B 2008; 112:4441-6. [DOI: 10.1021/jp709880b] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
12
|
Mishra B, Kumar BS, Priyadarsini K. Pulse and γ-radiolysis studies on aqueous solution of 1,1′-dimethyl-2-selenourea. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2007.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
13
|
Cardey B, Foley S, Enescu M. Mechanism of Thiol Oxidation by the Superoxide Radical. J Phys Chem A 2007; 111:13046-52. [DOI: 10.1021/jp0731102] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bruno Cardey
- University of Franche-Comte, Laboratoire de Microanalyses Nucleaires, UMR CEA E4, 16 route de Gray, 25030 Besancon, France
| | - Sarah Foley
- University of Franche-Comte, Laboratoire de Microanalyses Nucleaires, UMR CEA E4, 16 route de Gray, 25030 Besancon, France
| | - Mironel Enescu
- University of Franche-Comte, Laboratoire de Microanalyses Nucleaires, UMR CEA E4, 16 route de Gray, 25030 Besancon, France
| |
Collapse
|
14
|
Bobrowski K, Hug GL, Pogocki D, Marciniak B, Schöneich C. Stabilization of sulfide radical cations through complexation with the peptide bond: mechanisms relevant to oxidation of proteins containing multiple methionine residues. J Phys Chem B 2007; 111:9608-20. [PMID: 17658786 DOI: 10.1021/jp071191w] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The recent study on the *OH-induced oxidation of calmodulin, a regulatory "calcium sensor" protein containing nine methionine (Met) residues, has supported the first experimental evidence in a protein for the formation of S therefore N three-electron bonded radical complexes involving the sulfur atom of a methionine residue and the amide groups in adjacent peptide bonds. To characterize reactions of oxidized methionine residues in proteins containing multiple methionine residues in more detail, in the current study, a small model cyclic dipeptide, c-(L-Met-L-Met), was oxidized by *OH radicals generated via pulse radiolysis and the ensuing reactive intermediates were monitored by time-resolved UV-vis spectroscopic and conductometric techniques. The picture that emerges from this investigation shows there is an efficient formation of the Met (S therefore N) radicals, in spite of the close proximity of two sulfur atoms, located in the side chains of methionine residues, and in spite of the close proximity of sulfur atoms and oxygen atoms, located in the peptide bonds. Moreover, it is shown, for the first time, that the formation of Met(S therefore N) radicals can proceed directly, via H+-transfer, with the involvement of hydrogen from the peptide bond to an intermediary hydroxysulfuranyl radical. Ultimately, the Met(S therefore N) radicals decayed via two different pH-dependent reaction pathways, (i) conversion into sulfur-sulfur, intramolecular, three-electron-bonded radical cations and (ii) a proposed hydrolytic cleavage of the protonated form of the intramolecular, three-electron-bonded radicals [Met(S therefore N)/Met(S therefore NH)+] followed by electron transfer and decarboxylation. Surprisingly, also alpha-(alkylthio)alkyl radicals enter the latter mechanism in a pH-dependent manner. Density functional theory computations were performed on the model c-(L-Met-Gly) and its radicals in order to obtain optimizations and energies to aid in the interpretation of the experiments on c-(L-Met-L-Met).
Collapse
|
15
|
Tachikawa T, Tojo S, Fujitsuka M, Majima T. One-Electron Oxidation Pathways during β-Cyclodextrin-Modified TiO2 Photocatalytic Reactions. Chemistry 2006; 12:7585-94. [PMID: 16927273 DOI: 10.1002/chem.200600097] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The photocatalytic one-electron oxidation reactions of aromatic sulfides using the carboxymethyl-beta-cyclodextrin (CM-beta-CD)-modified TiO(2) nanoparticles (TiO(2)/CM-beta-CD) were investigated by using nano- and femtosecond transient absorption spectroscopies. The one-electron oxidation processes of the substrate (S) by the valence band hole (h(VB) (+)) at the TiO(2) surface and the trapped hole at the adsorption site of the CM-beta-CD (h(CD) (+)) were examined. The transient absorption spectra and time traces observed for the charge carriers and the radical cation of S (S(.+)) revealed that the one-electron oxidation reaction of S during the nano- and femtosecond laser flash photolyses of TiO(2)/CM-beta-CD is significantly enhanced relative to bare TiO(2). The kinetics of the decay and the dimerization processes between S(.+)s are discussed on the basis of the results obtained by the pulse radiolysis technique.
Collapse
Affiliation(s)
- Takashi Tachikawa
- The Institute of Scientific and Industrial Research (SANKEN) Osaka University Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | | | | | | |
Collapse
|
16
|
Tachikawa T, Tojo S, Fujitsuka M, Majima T. One-Electron Redox Processes during Polyoxometalate-Mediated Photocatalytic Reactions of TiO2 Studied by Two-Color Two-Laser Flash Photolysis. Chemistry 2006; 12:3124-31. [PMID: 16358350 DOI: 10.1002/chem.200501077] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The one-electron redox processes of several compounds during polyoxometalate (POM)-mediated photocatalytic reactions of TiO(2) were investigated using the two-color two-laser flash-photolysis technique. The efficiency of the one-electron oxidation of aromatic sulfides by the trapped hole (h(tr) (+)) or the surface-bound OH radical (OH(s) (.)) is found to be significantly enhanced due to electron transfer from the conduction band (CB) of TiO(2) to the POM. The efficiency of the electron transfer from the CB of TiO(2) to the POM decreases in the order H(2)W(12)O(40) (6-) < SiW(12)O(40) (4-) < PW(12)O(40) (3-), that is, it depends on the reduction potential (E(red)) of the POMs. Electron injection from PW(12)O(40) (4-) in the excited state (PW(12)O(40) (4-*)) to the CB of TiO(2) was clearly observed using the two-color two-laser flash-photolysis technique. Storage of electrons in the TiO(2)/PW(12)O(40) (3-)/methyl viologen (MV(2+)) ternary system was also achieved upon two-color two-laser irradiation.
Collapse
Affiliation(s)
- Takashi Tachikawa
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | | | | | | |
Collapse
|
17
|
Mishra B, Priyadarsini KI, Mohan H. Effect of pH on One-Electron Oxidation Chemistry of Organoselenium Compounds in Aqueous Solutions. J Phys Chem A 2006; 110:1894-900. [PMID: 16451022 DOI: 10.1021/jp055784n] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pulse radiolysis coupled with absorption detection has been employed to study one-electron oxidation of selenomethionine (SeM), selenocystine (SeCys), methyl selenocysteine (MeSeCys), and selenourea (SeU) in aqueous solutions. Hydroxyl radicals (*OH) in the pH range from 1 to 7 and specific one-electron oxidants Cl2*- (pH 1) and Br2*- (pH 7) have been used to carry out the oxidation reactions. The bimolecular rate constants for these reactions were reported to be in the range of 2 x 10(9) to 10 x 10(9) M(-1) s(-1). Reactions of oxidizing radicals with all these compounds produced selenium-centered radical cations. The structure and stability of the radical cation were found to depend mainly on the substituent and pH. SeM, at pH 7, produced a monomer radical cation (lambdamax approximately 380 nm), while at pH 1, a dimer radical cation was formed by the interaction between oxidized and parent SeM (lambdamax approximately 480 nm). Similarly, SeCys, at pH 7, on one-electron oxidation, produced a monomer radical cation (lambdamax approximately 460 nm), while at pH 1, the reaction produced a transient species with (lambdamax approximately 560 nm), which is also a monomer radical cation. MeSeCys on one-electron oxidation in the pH range from 1 to 7 produced monomer radical cations (lambdamax approximately 350 nm), while at pH < 0, the reaction produced dimer radical cations (lambdamax approximately 460 nm). SeU at all the pH ranges produced dimer radical cations (lambdamax approximately 410 nm). The association constants of the dimer radical cations of SeM, MeSeCys, and SeU were determined by following absorption changes at lambdamax as a function of concentration. From these studies it is concluded that formation of monomer and dimer radical cations mainly depends on the substitution, pH, and the heteroatoms like N and O. The availability of a lone pair on an N or O atom at the beta or gamma position results in monomer radical cations having intramolecular stabilization. When such a lone pair is not available, the monomer radical cation is converted into a dimer radical cation which acquires intermolecular stabilization by the other selenium atom. The pH dependency confirms the role of protonation on stabilization. The oxidation chemistry of these selenium compounds is compared with that of their sulfur analogues.
Collapse
Affiliation(s)
- B Mishra
- Radiation & Photo Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India
| | | | | |
Collapse
|
18
|
Mohan H, Mittal JP. Effect of substituents on different channels of OH radical reaction with substituted organic sulfides. Radiat Phys Chem Oxf Engl 1993 2005. [DOI: 10.1016/j.radphyschem.2005.04.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
19
|
Tachikawa T, Tojo S, Fujitsuka M, Majima T. Exclusion of Aromatic Radical Cations from Cyclodextrin Nanocavity Studied by Pulse Radiolysis. J Phys Chem B 2005; 109:17460-6. [PMID: 16853232 DOI: 10.1021/jp0528663] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The influence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) on the one-electron oxidation reaction of aromatic sulfides (S) with Br2*- and the decay process of the S radical cation (S*+) was investigated by pulse radiolysis. The dissociation kinetics of S*+ from the CD cavity was examined in terms of the apparent equilibrium constants (Kapp) for the formation and decay processes of S*+. Inhibition of the one-electron oxidation reaction of S by Br2*- was clearly observed in the presence of HP-beta-CD. On the basis of a comparison between the determined Kapp values, it was found that the binding ability of S*+ with HP-beta-CD is much lower than that of S, because of the hydrophobic nature of the cavity. The formation process of the dimer radical cation of 4-(methylthio)phenylmethanol ((MTPM)2*+), which is generated between MTPM(*+) and neutral MTPM in solution, was also inhibited by the addition of HP-beta-CD.
Collapse
Affiliation(s)
- Takashi Tachikawa
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | | | | | | |
Collapse
|
20
|
Strzelczak G, Korzeniowska-Sobczuk A, Bobrowski K. Electron spin resonance study of radiation-induced radicals in polycrystalline aromatic carboxylic acids containing a thioether group. Radiat Phys Chem Oxf Engl 1993 2005. [DOI: 10.1016/j.radphyschem.2004.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
21
|
Tachikawa T, Yoshida A, Tojo S, Sugimoto A, Fujitsuka M, Majima T. Evaluation of the Efficiency of the Photocatalytic One-Electron Oxidation Reaction of Aromatic Compounds Adsorbed on a TiO2 Surface. Chemistry 2004; 10:5345-53. [PMID: 15390135 DOI: 10.1002/chem.200400516] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The TiO2 photocatalytic one-electron oxidation mechanism of aromatic sulfides with a methylene bridging group (-(CH2)n-, n=0-4) between the 4-(methylthio)phenyl chromophore and the carboxylate binding group on the surface of a TiO2 powder slurried in acetonitrile (MeCN) has been investigated by time-resolved diffuse reflectance (TDR) spectroscopy. The electronic coupling element (H(DA)) between the hole donor and acceptor, which was estimated from the spectroscopic characteristics of the charge transfer (CT) complexes of the substrates (S) and the TiO2 surface, exhibited an exponential decline with the increasing of the methylene number of S. The determined decay factor (beta) of 9 nm(-1) also supports the fact that the 4-(methylthio)phenyl chromophore is separated from the TiO2 surface. The efficiency of the one-electron oxidation of S adsorbed on the TiO2 surface, which was determined from the relationship between the amount of adsorbates and the concentration of the generated radical cations, significantly depended on the H(DA) value, but not on the oxidation potential of S determined in homogeneous solution.
Collapse
Affiliation(s)
- Takashi Tachikawa
- Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | | | | | | | | | | |
Collapse
|
22
|
Tachikawa T, Tojo S, Fujitsuka M, Majima T. Influences of Adsorption on TiO2 Photocatalytic One-Electron Oxidation of Aromatic Sulfides Studied by Time-Resolved Diffuse Reflectance Spectroscopy. J Phys Chem B 2004. [DOI: 10.1021/jp037003t] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Takashi Tachikawa
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Sachiko Tojo
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Mamoru Fujitsuka
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Tetsuro Majima
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| |
Collapse
|
23
|
Mishra B, Maity DK, Priyadarsini KI, Mohan H, Mittal JP. One-Electron Oxidation of Selenourea in Aqueous Solution. J Phys Chem A 2004. [DOI: 10.1021/jp0371130] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- B. Mishra
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - D. K. Maity
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - K. I. Priyadarsini
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - H. Mohan
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - J. P. Mittal
- Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| |
Collapse
|