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Cho DW, Lee CW, Park JG, Oh SW, Sung NK, Park HJ, Kim KM, Mariano PS, Yoon UC. Exploration of photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone, and pyrrolidone derivatives. Photochem Photobiol Sci 2011; 10:1169-80. [PMID: 21472163 DOI: 10.1039/c0pp00372g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photochemical reactions of N-trimethylsilylmethyl-substituted uracil, pyridone and pyrrolidone derivatives were carried out to determine if silicone containing substituents have an impact on excited state reaction profiles. The results show that ultraviolet irradiation of N-trimethylsilylmethyl substituted uracils in the presence of substituted alkenes leads to efficient formation of both dimeric and cross [2+2]-cycloaddition products. Qualitatively similar observations were made in a study of the photochemistry of N-trimethylsilylmethyl-2-pyridone. The combined results demonstrate that [2+2]-photocycloaddition is a more efficient excited state reaction pathway for the uracil and pyridone substrates as compared to other processes, such as ylide-forming trimethylsilyl group C-to-O migration. Finally, photoreactions of N-trimethylsilylmethyl-2-pyrrolidone in solutions containing dipolarophiles, such as methyl acrylate, lead to the formation of the desilylation product, N-methyl-2-pyrrolidone by way of a simple, non-ylide generating, protodesilylation process. In addition, observations were made which show that orbital symmetry allowed photocycloreversion reactions of dimeric uracil derivatives, involving cyclobutane ring splitting, to take place. These processes, which lead to the formation of monomeric uracils, appear to be stimulated by the presence of electron donor groups on the cyclobutane ring, a likely result of a new SET promoted cyclobutane ring cleavage pathway. In the cases of N-trimethylsilylmethyl-substituted cyclobutane derivatives that possess phthalimide groups, highly efficient excited state cleavage of the cyclobutane moiety occurs to produce uracil derivatives and corresponding vinyl phthalimide.
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Affiliation(s)
- Dae Won Cho
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, 609-735, Korea
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Wöhrle D, Ardeshirpur A, Heuermann A, Müller S, Graschew G, Rinneberg H, Kohl M, Neukammer J. Polymeric porphyrins as new photocatalysts in photodynamic therapy of cancer. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19920590104] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Matsubara Y, Koga K, Kobayashi A, Konno H, Sakamoto K, Morimoto T, Ishitani O. Development of an efficient and durable photocatalytic system for hydride reduction of an NAD(P)+ model compound using a ruthenium(II) complex based on mechanistic studies. J Am Chem Soc 2010; 132:10547-52. [PMID: 20662527 DOI: 10.1021/ja1040122] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanism of photocatalytic reduction of 1-benzylnicotinamidium cation (BNA(+)) to the 1,4-dihydro form (1,4-BNAH) using [Ru(tpy)(bpy)(L)](2+) (Ru-L(2+), where tpy = 2,2':6',2''-terpyridine, bpy = 2,2'-bipyridine, and L = pyridine and MeCN) as a photocatalyst and NEt(3) as a reductant has been clarified. On the basis of this mechanistic study, an efficient and durable photocatalytic system for selective hydride reduction of an NAD(P)(+) model compound has been developed. The photocatalytic reaction is initiated by the formation of [Ru(tpy)(bpy)(NEt(3))](2+) (Ru-NEt(3)(2+)) via the photochemical ligand substitution of Ru-L(2+). For this reason, the production rate of 1,4-BNAH using [Ru(tpy)(bpy)(MeCN)](2+) (Ru-MeCN(2+)) as a photocatalyst, from which the quantum yield of photoelimination of the MeCN ligand is greater than that of the pyridine ligand from [Ru(tpy)(bpy)(pyridine)](2+) (Ru-py(2+)), was faster than that using Ru-py(2+), especially in the first stage of the photocatalytic reduction. The photoexcitation of Ru-NEt(3)(2+) yields [Ru(tpy)(bpy)H](+) (Ru-H(+)), which reacts with BNA(+) to give 1:1 adduct [Ru(tpy)(bpy)(1,4-BNAH)](2+) (Ru-BNAH(2+)). In the presence of excess NEt(3) in the reaction solution, a deprotonation of the carbamoyl group in Ru-BNAH(2+) proceeds rapidly, mainly forming [Ru(tpy)(bpy)(1,4-BNAH-H(+))](+) (Ru-(BNAH-H(+))(+)). Although photocleavage of the adduct yields 1,4-BNAH and the cycle is completed by the re-coordination of a NEt(3) molecule to the Ru(II) center, this process competes with hydride abstraction from Ru-(BNAH-H(+))(+) by BNA(+) giving 1,4-BNAH and [Ru(tpy)(bpy)(BNA(+)-H(+))](2+). This adduct was observed as the major complex in the reaction solution after the photocatalysis was depressed and is a dead-end product because of its stability. Based on the information about the reaction mechanism and the deactivation process, we have successfully developed a new photocatalytic system using Ru-MeCN(2+) with 2 M of NEt(3) as a reductant, which could reduce more than 59 equivalent amounts of an NAD(P)(+) model, 1-benzyl-N,N-diethylnicotinamidium cation, selectively to the corresponding 1,4-dihydro form in a 6 x 10(-4) quantum yield using 436-nm light.
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Affiliation(s)
- Yasuo Matsubara
- Department of Chemistry, Tokyo Institute of Technology, O-okayama 2-12-1, E1-9, Meguro-ku, Tokyo 152-8551, Japan
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Yasuda M, Nishinaka Y, Nakazono T, Hamasaki T, Nakamura N, Shiragami T, Pac C, Shima K. Photochemistry of Flavins in Micelles: Specific Effects of Anionic Surfactants on the Monomerization of Thymine Cyclobutane Dimers Photosensitized by Tetra-O-acyl Riboflavins*. Photochem Photobiol 2008. [DOI: 10.1111/j.1751-1097.1998.tb05186.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Budyka MF, Alfimov MV. Photochemical reactions of complexes of aromatic amines with polyhalomethanes. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1995v064n08abeh000170] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kobayashi A, Konno H, Sakamoto K, Sekine A, Ohashi Y, Iida M, Ishitani O. Transition metal complexes coordinated by an NAD(P)H model compound and their enhanced hydride-donating abilities in the presence of a base. Chemistry 2006; 11:4219-26. [PMID: 15864798 DOI: 10.1002/chem.200401211] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ruthenium(II) and rhenium(I) complexes containing an NAD(P)H model compound, 1-benzyl-1,4-dihydronicotinamide (BNAH), as ligand, [Ru(tpy)(bpy)(BNAH)]2+ (1 a) and [Re(bpy)(CO)3(BNAH)]+ (1 b), were quantitatively produced by the reaction of the corresponding metal hydrido complexes with BNA(+) (1-benzylnicotinamidium cation). In the presence of base with pK(a) = 8.9, 1 a and 1 b have much greater reducing power than "free" BNAH. The oxidation potentials of 1 a in the absence and the presence of triethylamine were 0.55 V and -0.04 V, respectively, versus Ag/AgNO(3), whereas that of "free" BNAH was 0.30 V. Spectroscopic results clearly showed that the base extracts a proton from the carbamoyl group on 1 a and 1 b to give the deprotonated BNAH coordinating to the transition-metal complexes [Ru(tpy)(bpy)(BNAH-H+)]+ (3 a) and [Re(bpy)(CO)3(BNAH-H+)] (3 b); this deprotonation underlies the enhancement in reducing ability. The deprotonated forms 3 a and 3 b can efficiently reduce other NAD(P) models to give the corresponding 1,4-dihydro form, resulting in the deprotonated BNA+ being coordinated to the metal complexes [Ru(tpy)(bpy)(BNA(+)-H+)]2+ (2 a) and [Re(bpy)(CO)3(BNA+-H+)]+ (2 b); "free" BNAH and the protonated adducts 1 a and 1 b cannot act in this way. X-ray crystallography was performed on the PF6- salt of 2 a, and showed that the deprotonated nitrogen atom on the carbamoyl group coordinates to the ruthenium(II) metal center with a bond length of 2.086(3) Angstroms. Infrared spectral data suggested that the deprotonated carbamoyl group on the reduced forms 3 a and 3 b is converted to the imido group, and that the oxygen atom coordinates to the metal center.
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Affiliation(s)
- Atsuo Kobayashi
- Graduate School of Science and Engineering, Saitama University, Japan
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Cabrera CG, de Waisbaum RG, Nudelman NS. Kinetic and mechanistic studies on the hydrolysis and photodegradation of diazepam and alprazolam. J PHYS ORG CHEM 2005. [DOI: 10.1002/poc.861] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sheng Z, Pan Y, Yan L, Hei X, Guo Z, Dai J, Song Q, Yu S. Steady-state and laser flash photolysis studies on the oxidative splitting of cyclobutane thymine dimer by triplet 9,10-anthraquinone-2-sulfonate. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/s1010-6030(03)00279-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Kobayashi A, Takatori R, Kikuchi I, Konno H, Sakamoto K, Ishitani O. Formation of Novel 1:1 Adducts Accompanied by Regioselective Hydride Transfer from Transition-Metal Hydrido Complexes to NAD(P) Models. Organometallics 2001. [DOI: 10.1021/om010362v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Atsuo Kobayashi
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
| | - Ryosuke Takatori
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
| | - Itsumi Kikuchi
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
| | - Hideo Konno
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
| | - Kazuhiko Sakamoto
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
| | - Osamu Ishitani
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan
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Tamai T, Ichinose N, Tanaka T, Sasuga T, Hashida I, Mizuno K. Generation of Polyphenylene Radical Cations and Their Cosensitization Ability in the 9,10-Dicyanoanthracene-Sensitized Photochemical Chain Reactions of 1,2-Bis(4-methoxyphenyl)cyclopropane. J Org Chem 1998. [DOI: 10.1021/jo971649y] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Toshiyuki Tamai
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | - Nobuyuki Ichinose
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | - Tomoko Tanaka
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | - Tsuneo Sasuga
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | - Isao Hashida
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | - Kazuhiko Mizuno
- Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8533, Japan, Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minamimachi, Neyagawa, Osaka 572-0019, Japan, and Department of Applied Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
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Spiller W, Wöhrle D, Schulz-Ekloff G, Ford WT, Schneider G, Stark J. Photo-oxidation of sodium sulfide by sulfonated phthalocyanines in oxygen-saturated aqueous solutions containing detergents or latexes. J Photochem Photobiol A Chem 1996. [DOI: 10.1016/1010-6030(95)04248-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Borsarelli CD, Montejano HA, Cosa JJ, Previtali CM. Medium effects on the photochemical reaction between pyrene and indole. A laser flash photolysis study. J Photochem Photobiol A Chem 1995. [DOI: 10.1016/1010-6030(95)04124-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yasuda M, Nakazono T, Hamasaki T, Nishinaka Y, Nakamura N, Pac C, Shima K. Remarkable Effect of Surfactant on Flavin Photochemistry: Monomerization of Thymine Cyclobutane Dimers Photosensitized by Flavins in the Presence of SDS in Aqueous Solution. CHEM LETT 1995. [DOI: 10.1246/cl.1995.563] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Borsarelli C, Chesta C, Cosa J, Crystall B, Phillips D. Quenching of an intramolecular naphthalene-triethylamine exciplex by tetrabutylammonium perchlorate. Evidence for the formation of an emissive complex. Chem Phys Lett 1995. [DOI: 10.1016/0009-2614(94)01307-h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nuclear magnetic resonance and UV spectral probe of photochemical steady states of vitamin K1. J Photochem Photobiol A Chem 1994. [DOI: 10.1016/1010-6030(94)80060-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ishitani O, Inoue N, Koike K, Ibusuki T. A novel type of hydride-transfer photocatalysis by RuII–pyridine complexes: regiocontrolled reduction of an NAD(P) model compound by triethylamine. ACTA ACUST UNITED AC 1994. [DOI: 10.1039/c39940000367] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Miyake K, Masaki Y, Miyamoto I, Yanagida S, Ohno T, Yoshimura A, Pac C. Flavin-photosensitized monomerization of dimethylthymine cyclobutane dimer in the presence of magnesium perchlorate. Photochem Photobiol 1993; 58:631-6. [PMID: 8284317 DOI: 10.1111/j.1751-1097.1993.tb04944.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have investigated the photosensitized monomerization of the cis,syn-cyclobutane dimer of 1,3-dimethylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction.
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Affiliation(s)
- K Miyake
- Department of Chemical Process Engineering, Faculty of Engineering, Osaka University, Japan
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Nakanishi K, Mizuno K, Otsuji Y. Photosubstitution of Dicyanobenzenes by Allylic Silanes, Germanes, and Stannanes via Photoinduced Electron Transfer. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1993. [DOI: 10.1246/bcsj.66.2371] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kim ST, Sancar A. Photochemistry, photophysics, and mechanism of pyrimidine dimer repair by DNA photolyase. Photochem Photobiol 1993; 57:895-904. [PMID: 8337263 DOI: 10.1111/j.1751-1097.1993.tb09232.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
DNA photolyases photorepair pyrimidine dimers (Pyr < > Pyr) in DNA as well as RNA and thus reverse the harmful effects of UV-A (320-400 nm) and UV-B (280-320 nm) radiations. Photolyases from various organisms have been found to contain two noncovalently bound cofactors; one is a fully reduced flavin adenine dinucleotide (FADH-) and the other, commonly known as second chromophore, is either methenyltetrahydrofolate (MTHF) or 8-hydroxydeazaflavin (8-HDF). The second chromophore in photolyase is a light-harvesting molecule that absorbs mostly in the near-UV and visible wavelengths (300-500 nm) with its high extinction coefficient. The second chromophore then transfers its excitation energy to the FADH-. Subsequently, the photoexcited FADH- transfers an electron to the Pyr < > Pyr generating a dimer radical anion (Pyr < > Pyr.-) and a neutral flavin radical (FADH.). The Pyr < > Pyr.- is very unstable and undergoes spontaneous splitting followed by a back electron transfer to the FADH.. In addition to the main catalytic cofactor FADH-, a Trp (Trp277 in Escherichia coli) in apophotolyase, independent of other chromophores, also functions as a sensitizer to repair Pyr < > Pyr by direct electron transfer.
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Affiliation(s)
- S T Kim
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599-7260
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Yamashita T, Tsurusako T, Nakamura N, Yasuda M, Shima K. Electron-Transfer Photosensitized Oxygenation of Stilbene and Naphthalene Derivatives in the Presence of Acetate Ion. Controlling the Reaction of the Cation Radicals by Weak-Nucleophilic Salts. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1993. [DOI: 10.1246/bcsj.66.857] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Masaki Y, Miyake K, Yanagida S, Pac C. Participation of a Chain Mechanism in Efficient Monomerization of Dimethylthymine Cyclobutane Dimer Photosensitized by a Flavin in the Presence of Perchloric Acid. CHEM LETT 1992. [DOI: 10.1246/cl.1992.319] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kim ST, Rose SD. Pyrimidine dimer splitting in covalently linked dimer-arylamine systems. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1992; 12:179-91. [PMID: 1619516 DOI: 10.1016/1011-1344(92)85007-h] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cyclobutadipyrimidines (pyrimidine dimers) undergo photosplitting which is sensitized by electron donors. We prepared a series of compounds in which a dimer is directly linked to an arylamine, which acts as sensitizer for dimer splitting. Two diastereomers of the dimer-arylamine exhibited very different splitting efficiencies. Also studied were N-methyl, ring methoxy, as well as deuterated derivatives of the sensitizer. These dimer-arylamines had an absorption band with lambda max approximately 300 nm. In each case intramolecular photosensitization of dimer splitting was highly dependent on the solvent, ranging in one instance from phi spl = 0.02 in water to a high value of 0.31 in the least polar solvent mixture examined (1,4-dioxane: isopentane, 1:99). A mechanism is proposed which involves photoinduced electron transfer from arylamine to dimer and splitting of the dimer radical anion. The dependence of splitting on the solvent was rationalized on the basis of retardation of back electron transfer due to Marcus inverted behavior of the charge-separated species. Photolyases might achieve their high efficiency of dimer splitting in part by employing a hydrophobic active site to slow back electron transfer in a similar manner.
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Affiliation(s)
- S T Kim
- Department of Chemistry and Biochemistry, Arizona State University, Tempe 85287-1604
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Yamashita T, Tsurusako T, Yasuda M, Shima K. Unusual Effects of Acetate Ion on Photosensitized Oxygenation of Naphthalene Derivatives via Electron Transfer. CHEM LETT 1991. [DOI: 10.1246/cl.1991.1487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Tamiaki H, Maruyama K. Synthesis and electron-transfer efficiency of oligopeptide-bridged donor–acceptor molecules. ACTA ACUST UNITED AC 1991. [DOI: 10.1039/p19910000817] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pac C, Miyamoto I, Masaki Y, Furusho S, Yanagida S, Ohno T, Yoshimura A. Chloranil-photosensitized monomerization of dimethylthymine cyclobutane dimers and effect of magnesium perchlorate. Photochem Photobiol 1990; 52:973-9. [PMID: 1962858 DOI: 10.1111/j.1751-1097.1990.tb01813.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The photosensitized monomerization of the cyclobutane dimers of 1,3-dimethylthymine by p-chloranil was investigated by means of steady-state irradiation and laser-flash photolysis. Quantum yields for the monomerization are 0.34 for the cis,syn dimer, 0.39 for the trans,syn dimer, and much less than 10(-2) for the cis,anti isomer. Formation of the chloranil anion radical associated with quenching of triplet chloranil by the dimers demonstrates that electron transfer from dimers to triplet chloranil occurs to initiate the monomerization. Kinetic analysis suggested that the syn-dimer cation radicals undergo the ring cleavage at greater than or equal to 10(9) s-1 before escaping from the solvent cage, while the reactivity of the anti-dimer cation radical is very low. The different reactivities of the syn and anti dimer cation radicals are discussed in terms of through-bond coupling between the n orbitals of N(1) and N(1') involving the cyclobutane-ring sigma orbitals. In the cases of the syn-dimers, the sensitizer-dimer ion-radical pairs undergo the rapid geminate recombination that works as a major energy dissipating channel responsible for the lower-than-unity quantum yields. It has been found that the presence of Mg(ClO4)2 at 0.1 M enhances approximately 1.5 times either the monomerization of the syn dimers or the formation of the chloranil anion radical. A laser-flash photolysis study shows that Mg2+ forms a complex with either the triplet or the anion radical of chloranil. The net salt effects are attributed to the retardation of the rapid geminate recombination by the participation of Mg2+ in the sensitizer-dimer ion-radical pairs.
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Affiliation(s)
- C Pac
- Department of Chemical Process Engineering, Faculty of Engineering, Osaka University, Japan
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Kim ST, Hartman RF, Rose SD. Solvent dependence of pyrimidine dimer splitting in a covalently linked dimer-indole system. Photochem Photobiol 1990; 52:789-94. [PMID: 2089427 DOI: 10.1111/j.1751-1097.1990.tb08683.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cyclobutadipyrimidines (pyrimidine dimers) undergo splitting that is photosensitized by indole derivatives. We have prepared a compound in which a two-carbon linker connects a dimer to an indolyl group. Indolyl fluorescence quenching indicated that the two portions of the molecule interact in the excited state. Intramolecular photosensitization of dimer splitting was remarkably solvent dependent, ranging from phi spl = 0.06 in water to a high value of phi spl = 0.41 in the least polar solvent mixture examined, 1,4-dioxane-isopentane(5 : 95). A derivative with a 5-methoxy substituent on the indolyl ring behaved similarly. These results have been interpreted in terms of electron transfer from the excited indolyl group to the dimer, which would produce a charge-separated species. The dimer anion within such a species could split or undergo back electron transfer. The possibility that back electron transfer is in the Marcus inverted region can be used to rationalize the observed solvent dependence of splitting. In the inverted region, the high driving force of a charge recombination exceeds the reorganization energy of the solvent, which is less for solvents of low polarity than those of high polarity. If this theory is applicable to the hypothetical charge-separated species, a slower back electron transfer, and consequently higher splitting efficiencies, would be expected in solvents of lower polarity. Photolyases may have evolved in which a low polarity active site retards back transfer of an electron and thereby contributes to the efficiency of the enzymatic dimer splitting.
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Affiliation(s)
- S T Kim
- Department of Chemistry, Arizona State University, Tempe 85287-1604
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Young T, Nieman R, Rose SD. Photo-CIDNP detection of pyrimidine dimer radical cations in anthraquinonesulfonate-sensitized splitting. Photochem Photobiol 1990; 52:661-8. [PMID: 2089415 DOI: 10.1111/j.1751-1097.1990.tb08664.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Anthraquinone-2-sulfonate (AQS) photosensitizes pyrimidine dimer splitting. Electron abstraction from the dimer is thought to induce dimer splitting, but direct evidence for the existence and intermediacy of dimer radical cations has been lacking. By employing photochemically induced dynamic nuclear polarization, we have found emission signals in the NMR spectra of dimers upon photolysis of dimers in the presence of anthraquinone-2-sulfonate. The two dimers employed were cis, syn-thymine dimer in which the N(1)-positions were linked by a three-carbon bridge and the N(3), N(3')-dimethyl derivative of that compound. The anthraquinone-2-sulfonate sensitized photochemically induced dynamic nuclear polarization spectrum of the methylated derivative exhibited an emission signal from the dimer-C(6) hydrogens. This result implied the existence of a dimer radical cation (mD+.) formed by electron abstraction by excited anthraquinone-2-sulfonate and nuclear spin sorting within a solvent caged radical ion pair [mD+. AQS-.]. Product pyrimidine photochemically induced dynamic nuclear polarization signals were also seen [enhanced absorption by C(6)-hydrogens and emission by C(5)-methyl groups]. Nuclear spin polarization in the product resulted from spin sorting in one or more of its precursors, including mD+. The results support the conclusion that dimer radical cations not only exist but are intermediates in the photosensitized splitting of pyrimidine dimers by anthraquinonesulfonate.
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Affiliation(s)
- T Young
- Department of Chemistry, Arizona State University, Tempe 85287-1604
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