1
|
Kidd JB, Fiala TA, Swords WB, Park Y, Meyer KA, Sanders KM, Guzei IA, Wright JC, Yoon TP. Enantioselective Paternò-Büchi Reactions: Strategic Application of a Triplet Rebound Mechanism for Asymmetric Photocatalysis. J Am Chem Soc 2024; 146:15293-15300. [PMID: 38781687 PMCID: PMC11224773 DOI: 10.1021/jacs.4c02975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The Paternò-Büchi reaction is the [2 + 2] photocycloaddition of a carbonyl with an alkene to afford an oxetane. Enantioselective catalysis of this classical photoreaction, however, has proven to be a long-standing challenge. Many of the best-developed strategies for asymmetric photochemistry are not suitable to address this problem because the interaction of carbonyls with Brønsted or Lewis acidic catalysts can alter the electronic structure of their excited state and divert their reactivity toward alternate photoproducts. We show herein that a triplet rebound strategy enables the stereocontrolled reaction of an excited-state carbonyl compound in its native, unbound state. These studies have resulted in the development of the first highly enantioselective catalytic Paternò-Büchi reaction, catalyzed by a novel hydrogen-bonding chiral Ir photocatalyst.
Collapse
Affiliation(s)
- Jesse B. Kidd
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Tahoe A. Fiala
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Wesley B. Swords
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Yerin Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea; Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Kent A. Meyer
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Kyana M. Sanders
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - John C. Wright
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| | - Tehshik P. Yoon
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison WI 53706 USA
| |
Collapse
|
2
|
Yan P, Stegbauer S, Wu Q, Kolodzeiski E, Stein CJ, Lu P, Bach T. Enantioselective Intramolecular ortho Photocycloaddition Reactions of 2-Acetonaphthones. Angew Chem Int Ed Engl 2024; 63:e202318126. [PMID: 38275271 DOI: 10.1002/anie.202318126] [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: 11/27/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 01/27/2024]
Abstract
2-Acetonaphthones, which bear an alkenyl group tethered to its C1 carbon atom via an oxygen atom, were found to undergo an enantioselective intramolecular ortho photocycloaddition reaction. A chiral oxazaborolidine Lewis acid leads to a bathochromic absorption shift of the substrate and enables an efficient enantioface differentiation. Visible light irradiation (λ=450 nm) triggers the reaction which is tolerant of various groups at almost any position except carbon atom C8 (16 examples, 53-99 % yield, 80-97 % ee). Consecutive reactions were explored including a sensitized rearrangement to tetrahydrobiphenylenes, which occurred with full retention of configuration. Evidence was collected that the catalytic photocycloaddition occurs via triplet intermediates, and the binding mode of the acetonaphthone to the chiral Lewis acid was elucidated by DFT calculations.
Collapse
Affiliation(s)
- Peng Yan
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Simone Stegbauer
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Qinqin Wu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Elena Kolodzeiski
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Christopher J Stein
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Ping Lu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| |
Collapse
|
3
|
Liu Y, Yang F, Liu S, Zhang X, Li M. Molecular characteristics of microalgal extracellular polymeric substances were different among phyla and correlated with the extracellular persistent free radicals. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159704. [PMID: 36302439 DOI: 10.1016/j.scitotenv.2022.159704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Extracellular polymeric substance (EPS) plays essential roles in microalgal adaptation to the external environment and aggregate formation. The molecular characteristics of EPS and extracellular persistent free radicals (PFRs) of 15 microalgal species belonging to three phyla were analyzed using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), three-dimensional fluorescence excitation-emission matrices combined with parallel factor analysis (EEM-PARAFAC), and Electron Paramagnetic Resonance Spectrometer (EPR). Lignin accounted for the highest proportion of EPS for Cyanophyta and the proportion of lipids was higher for Bacillariophyta. The presence of PFRs was detected on the cell surfaces of all microalgae species (excluding Cyclotella sp.). The intensity of carbon-centered PFRs was positively correlated with the proportions of humic-like component and lignin, but was negatively correlated with the proportion of lipids in microalgal EPS. Following EPS extraction, carbon- and oxygen-centered free radicals were still detectable on the surface of microalgae. Given the high intensity of PFRs produced by Cyanophyta, the level of PFRs in eutrophic lakes and reservoirs predominated by Cyanophyta may be considerably high. Other organisms in the water column, such as bacteria and zooplankton are bound to be stressed by elevated level of PFRs. The ecological functions and environmental risks of PFRs carried by microalgae still need to be explored in follow-up research.
Collapse
Affiliation(s)
- Yang Liu
- College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, PR China
| | - Fang Yang
- College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, PR China
| | - Siwan Liu
- College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, PR China
| | - Xinpeng Zhang
- College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, PR China
| | - Ming Li
- College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, PR China.
| |
Collapse
|
4
|
Stegbauer S, Jandl C, Bach T. Chiral Lewis acid catalysis in a visible light-triggered cycloaddition/rearrangement cascade. Chem Sci 2022; 13:11856-11862. [PMID: 36320923 PMCID: PMC9580482 DOI: 10.1039/d2sc03159k] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 09/18/2022] [Indexed: 07/10/2024] Open
Abstract
Cascade (domino) reactions facilitate the formation of complex molecules from simple starting materials in a single operation. It was found that 1-naphthaldehyde derivatives can be converted to enantioenriched (82-96% ee) polycyclic benzoisochromenes via a cascade of ortho photocycloaddition and ensuing acid-catalysed rearrangement reactions. The cascade was initiated by irradiation with visible light (λ = 457 nm) and catalysed by a chiral AlBr3-activated 1,3,2-oxazaborolidine (14 examples, 65-93% yield). The absolute configuration of the products was elucidated by single crystal X-ray crystallography. Mechanistic experiments suggest that the ortho photocycloaddition occurs on the triplet hypersurface and that the chiral catalyst induces in this step the observed enantioselectivity.
Collapse
Affiliation(s)
- Simone Stegbauer
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
| | - Christian Jandl
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
| | - Thorsten Bach
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
| |
Collapse
|
5
|
Yu H, Zhan T, Zhou Y, Chen L, Liu X, Feng X. Visible-Light-Activated Asymmetric Addition of Hydrocarbons to Pyridine-Based Ketones. ACS Catal 2022. [DOI: 10.1021/acscatal.2c00789] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Han Yu
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Tangyu Zhan
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Yuqiao Zhou
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Long Chen
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Xiaohua Liu
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| |
Collapse
|
6
|
Xiao J, Lu S, Jia G, Wang Q, Li C. Relation Between Coordination and Lewis‐Acid Property of MOF‐Derived Mononuclear Zn(II) Catalyst Toward Epoxide Hydroxylation. ChemCatChem 2021. [DOI: 10.1002/cctc.202101340] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Juan‐Ding Xiao
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China
| | - Sheng‐Mei Lu
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China
| | - Guo‐Qing Jia
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China
| | - Qing‐Nan Wang
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China
| | - Can Li
- State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 P. R. China
| |
Collapse
|
7
|
Peschel MT, Kabaciński P, Schwinger DP, Thyrhaug E, Cerullo G, Bach T, Hauer J, Vivie‐Riedle R. Activation of 2‐Cyclohexenone by BF
3
Coordination: Mechanistic Insights from Theory and Experiment. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Martin T. Peschel
- Department Chemie Ludwig-Maximilians-Universität München 81377 München Germany
| | - Piotr Kabaciński
- IFN-CNR and Dipartimento di Fisica Politecnico di Milano 20133 Milano Italy
| | - Daniel P. Schwinger
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Erling Thyrhaug
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Giulio Cerullo
- IFN-CNR and Dipartimento di Fisica Politecnico di Milano 20133 Milano Italy
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Jürgen Hauer
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Regina Vivie‐Riedle
- Department Chemie Ludwig-Maximilians-Universität München 81377 München Germany
| |
Collapse
|
8
|
Peschel MT, Kabaciński P, Schwinger DP, Thyrhaug E, Cerullo G, Bach T, Hauer J, de Vivie-Riedle R. Activation of 2-Cyclohexenone by BF 3 Coordination: Mechanistic Insights from Theory and Experiment. Angew Chem Int Ed Engl 2021; 60:10155-10163. [PMID: 33595902 PMCID: PMC8252487 DOI: 10.1002/anie.202016653] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/01/2021] [Indexed: 11/22/2022]
Abstract
Lewis acids have recently been recognized as catalysts enabling enantioselective photochemical transformations. Mechanistic studies on these systems are however rare, either due to their absorption at wavelengths shorter than 260 nm, or due to the limitations of theoretical dynamic studies for larger complexes. In this work, we overcome these challenges and employ sub-30-fs transient absorption in the UV, in combination with a highly accurate theoretical treatment on the XMS-CASPT2 level. We investigate 2-cyclohexenone and its complex to boron trifluoride and analyze the observed dynamics based on trajectory calculations including non-adiabatic coupling and intersystem crossing. This approach explains all ultrafast decay pathways observed in the complex. We show that the Lewis acid remains attached to the substrate in the triplet state, which in turn explains why chiral boron-based Lewis acids induce a high enantioselectivity in photocycloaddition reactions.
Collapse
Affiliation(s)
- Martin T Peschel
- Department Chemie, Ludwig-Maximilians-Universität München, 81377, München, Germany
| | - Piotr Kabaciński
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, 20133, Milano, Italy
| | - Daniel P Schwinger
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Erling Thyrhaug
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Giulio Cerullo
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, 20133, Milano, Italy
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Jürgen Hauer
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | | |
Collapse
|
9
|
|
10
|
Stegbauer S, Jeremias N, Jandl C, Bach T. Reversal of reaction type selectivity by Lewis acid coordination: the ortho photocycloaddition of 1- and 2-naphthaldehyde. Chem Sci 2019; 10:8566-8570. [PMID: 31803430 PMCID: PMC6839505 DOI: 10.1039/c9sc03315g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/26/2019] [Indexed: 11/26/2022] Open
Abstract
The value of a specific substrate class for synthetic applications is greatly enhanced if different types of reactions can be performed selectively upon a judicious choice of reaction conditions. In the present study it was shown that the typical photochemical behaviour of naphthaldehydes is completely altered in the presence of Lewis acids. Without Lewis acids, reactions at the carbonyl group are exclusively observed while Lewis acids facilitate a visible light-mediated cycloaddition at the arene core providing access to products of aromatic C-H functionalization via cyclobutane intermediates.
Collapse
Affiliation(s)
- Simone Stegbauer
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Noah Jeremias
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| |
Collapse
|
11
|
Affiliation(s)
- Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- Faculty of Science and Engineering Meijo University, SENTAN, Japan, Science and Technology Agency (JST) Nagoya, Aichi 468-8502 Japan
| | - Jieun Jung
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| |
Collapse
|
12
|
Ohkubo K, Hirose K, Fukuzumi S. Solvent-Free Photooxidation of Alkanes by Dioxygen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone via Photoinduced Electron Transfer. Chem Asian J 2016; 11:2255-9. [DOI: 10.1002/asia.201600828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Kei Ohkubo
- Division of Applied Chemistry; Graduate School of Engineering; Osaka University, Suita; Osaka 565-0871 Japan
- Department of Material and Life Science; Graduate School of Engineering; Osaka University and SENTAN Japan Science and Technology Agency (JST), Suita; Osaka 565-0871 Japan
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Kensaku Hirose
- Department of Material and Life Science; Graduate School of Engineering; Osaka University and SENTAN Japan Science and Technology Agency (JST), Suita; Osaka 565-0871 Japan
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
- Faculty of Science and Technology; Meijo University, SENTAN Japan Science and Technology Agency (JST), Nagoya; Aichi 468-8502 Japan
| |
Collapse
|
13
|
Levin JR, Dorfner WL, Carroll PJ, Schelter EJ. Control of cerium oxidation state through metal complex secondary structures. Chem Sci 2015; 6:6925-6934. [PMID: 29861931 PMCID: PMC5951102 DOI: 10.1039/c5sc02607e] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 08/10/2015] [Indexed: 12/20/2022] Open
Abstract
A series of alkali metal cerium diphenylhydrazido complexes, M x (py) y [Ce(PhNNPh)4], M = Li, Na, and K, x = 4 (Li and Na) or 5 (K), and y = 4 (Li), 8 (Na), or 7 (K), were synthesized to probe how a secondary coordination sphere would modulate electronic structures at a cerium cation. The resulting electronic structures of the heterobimetallic cerium diphenylhydrazido complexes were found to be strongly dependent on the identity of the alkali metal cations. When M = Li+ or Na+, the cerium(iii) starting material was oxidized with concomitant reduction of 1,2-diphenylhydrazine to aniline. Reduction of 1,2-diphenylhydrazine was not observed when M = K+, and the complex remained in the cerium(iii) oxidation state. Oxidation of the cerium(iii) diphenylhydrazido complex to the Ce(iv) diphenylhydrazido one was achieved through a simple cation exchange reaction of the alkali metals. UV-Vis spectroscopy, FTIR spectroscopy, electrochemistry, magnetic susceptibility, and DFT studies were used to probe the oxidation state and the electronic changes that occurred at the metal centre.
Collapse
Affiliation(s)
- Jessica R Levin
- Roy and Diana T. Vagelos Laboratories , Department of Chemistry , University of Pennsylvania , 231 South 34th St. , Philadelphia , Pennsylvania 19104 , USA . ; Tel: +1 215-898-8633
| | - Walter L Dorfner
- Roy and Diana T. Vagelos Laboratories , Department of Chemistry , University of Pennsylvania , 231 South 34th St. , Philadelphia , Pennsylvania 19104 , USA . ; Tel: +1 215-898-8633
| | - Patrick J Carroll
- Roy and Diana T. Vagelos Laboratories , Department of Chemistry , University of Pennsylvania , 231 South 34th St. , Philadelphia , Pennsylvania 19104 , USA . ; Tel: +1 215-898-8633
| | - Eric J Schelter
- Roy and Diana T. Vagelos Laboratories , Department of Chemistry , University of Pennsylvania , 231 South 34th St. , Philadelphia , Pennsylvania 19104 , USA . ; Tel: +1 215-898-8633
| |
Collapse
|
14
|
Brimioulle R, Bauer A, Bach T. Enantioselective Lewis Acid Catalysis in Intramolecular [2 + 2] Photocycloaddition Reactions: A Mechanistic Comparison between Representative Coumarin and Enone Substrates. J Am Chem Soc 2015; 137:5170-6. [PMID: 25806816 DOI: 10.1021/jacs.5b01740] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The intramolecular [2 + 2] photocycloaddition of three 4-(alk-4-enyl)coumarins and three 1-(alk-4-enoyl)-2,3-dihydropyridones was studied in the absence and in the presence of Lewis acids (irradiation wavelength λ = 366 nm). Spectral and kinetic data were collected for the respective parent compounds with a pent-4-enyl and a pent-4-enoyl chain. For the substrates with a methyl group in cis- or trans-position of the terminal alkene carbon atom (hex-4-enyl and hex-4-enoyl substitution), the stereochemical outcome of the [2 + 2] photocycloaddition was investigated. The mechanistic course of the uncatalyzed coumarin reactions was found to be a singlet pathway, whereas Lewis acid-catalyzed reactions proceeded with higher reaction rates in the triplet manifold. Contrary to that, the dihydropyridones underwent a fast triplet reaction in the absence of the Lewis acid. In the presence of a chiral Lewis acid the reactions slowed down but, due to the high extinction coefficient of the Lewis acid/dihydropyridone complexes at λ = 366 nm, still resulted in high enantioselectivity.
Collapse
Affiliation(s)
- Richard Brimioulle
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Andreas Bauer
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| |
Collapse
|
15
|
D'Souza F, Imahori H. Preface — Special Issue in Honor of Professor Shunichi Fukuzumi. J PORPHYR PHTHALOCYA 2015. [DOI: 10.1142/s1088424615020010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
16
|
Sasaki S, Niko Y, Igawa K, Konishi GI. Aggregation-induced emission active D-π-A binaphthyl luminophore with dual-mode fluorescence. RSC Adv 2014. [DOI: 10.1039/c4ra05871b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
17
|
Li N, Zhang X, Xu X, Chen Y, Qiu R, Chen J, Wang X, Yin SF. Synthesis and Structures of Air-Stable Binuclear Hafnocene Perfluorobutanesulfonate and Perfluorobenzenesulfonate and their Catalytic Application in CC Bond-Forming Reactions. Adv Synth Catal 2013. [DOI: 10.1002/adsc.201300439] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
18
|
Yasui S, Tsujimoto M. Investigation of non-Rehm-Weller kinetics in the electron transfer from trivalent phosphorus compounds to singlet excited sensitizers. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3170] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Shinro Yasui
- Institute of Human and Environmental Sciences; Tezukayama University; Gakuen-Minami Nara 631-8585 Japan
| | - Munekazu Tsujimoto
- Institute of Human and Environmental Sciences; Tezukayama University; Gakuen-Minami Nara 631-8585 Japan
| |
Collapse
|
19
|
|
20
|
Mahoney BD, Piro NA, Carroll PJ, Schelter EJ. Synthesis, electrochemistry, and reactivity of cerium(III/IV) methylene-bis-phenolate complexes. Inorg Chem 2013; 52:5970-7. [PMID: 23621676 DOI: 10.1021/ic400202r] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A series of cerium complexes containing a 2,2'-methylenebis(6-tert-butyl-4-methylphenolate) (MBP(2-)) ligand framework is described. Electrochemical studies of the compound [Li(THF)2Ce(MBP)2(THF)2] (1) reveal that the metal based oxidation wave occurs at -0.93 V vs Fc/Fc(+). This potential demonstrates significant stabilization of the cerium(IV) ion in the MBP(2-) framework with a shift of ∼2.25 V from the typically reported value for the cerium(III/IV) couple of E°' = +1.30 V vs Fc/Fc(+) for Ce(ClO4)3 in HClO4 solutions. Compound 1 undergoes oxidation to form stable cerium(IV) species in the presence of a variety of common oxidants. The coordination of the redox-active ligands 2,2'-bipyridine and benzophenone to 1 result in complexes in which no apparent metal-to-ligand charge transfer occurs and the cerium ion remains in the +3 oxidation state.
Collapse
Affiliation(s)
- Brian D Mahoney
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | | | | | | |
Collapse
|
21
|
Kawashima T, Manda S, Uto Y, Ohkubo K, Hori H, Matsumoto KI, Fukuhara K, Ikota N, Fukuzumi S, Ozawa T, Anzai K, Nakanishi I. Kinetics and Mechanism for the Scavenging Reaction of the 2,2-Diphenyl-1-picrylhydrazyl Radical by Synthetic Artepillin C Analogues. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2012. [DOI: 10.1246/bcsj.20120005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tomonori Kawashima
- Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS)
| | - Sushma Manda
- Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS)
| | - Yoshihiro Uto
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University
- ALCA, Japan Science and Technology Agency (JST)
| | - Hitoshi Hori
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima
| | - Ken-ichiro Matsumoto
- Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS)
| | - Kiyoshi Fukuhara
- Division of Organic Chemistry, National Institute of Health Sciences (NIHS)
| | | | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University
- ALCA, Japan Science and Technology Agency (JST)
- Department of Bioinspired Science, Ewha Womans University
| | | | - Kazunori Anzai
- School of Pharmaceutical Sciences, Nihon Pharmaceutical University
| | - Ikuo Nakanishi
- Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS)
| |
Collapse
|
22
|
Niko Y, Hiroshige Y, Kawauchi S, Konishi GI. Fundamental photoluminescence properties of pyrene carbonyl compounds through absolute fluorescence quantum yield measurement and density functional theory. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.05.072] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
23
|
Park J, Morimoto Y, Lee YM, Nam W, Fukuzumi S. Proton-Promoted Oxygen Atom Transfer vs Proton-Coupled Electron Transfer of a Non-Heme Iron(IV)-Oxo Complex. J Am Chem Soc 2012; 134:3903-11. [DOI: 10.1021/ja211641s] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jiyun Park
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Yuma Morimoto
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, ALCA, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871,
Japan
| | - Yong-Min Lee
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Wonwoo Nam
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Shunichi Fukuzumi
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
- Department of Material and Life
Science, Graduate School of Engineering, Osaka University, ALCA, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871,
Japan
| |
Collapse
|
24
|
Park J, Morimoto Y, Lee YM, You Y, Nam W, Fukuzumi S. Scandium ion-enhanced oxidative dimerization and N-demethylation of N,N-dimethylanilines by a non-heme iron(IV)-oxo complex. Inorg Chem 2011; 50:11612-22. [PMID: 22010853 DOI: 10.1021/ic201545a] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Oxidative dimerization of N,N-dimethylaniline (DMA) occurs with a nonheme iron(IV)-oxo complex, [Fe(IV)(O)(N4Py)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), to yield the corresponding dimer, tetramethylbenzidine (TMB), in acetonitrile. The rate of the oxidative dimerization of DMA by [Fe(IV)(O)(N4Py)](2+) is markedly enhanced by the presence of scandium triflate, Sc(OTf)(3) (OTf = CF(3)SO(3)(-)), when TMB is further oxidized to the radical cation (TMB(•+)). In contrast, we have observed the oxidative N-demethylation with para-substituted DMA substrates, since the position of the C-C bond formation to yield the dimer is blocked. The rate of the oxidative N-demethylation of para-substituted DMA by [Fe(IV)(O)(N4Py)](2+) is also markedly enhanced by the presence of Sc(OTf)(3). In the case of para-substituted DMA derivatives with electron-donating substituents, radical cations of DMA derivatives are initially formed by Sc(3+) ion-coupled electron transfer from DMA derivatives to [Fe(IV)(O)(N4Py)](2+), giving demethylated products. Binding of Sc(3+) to [Fe(IV)(O)(N4Py)](2+) enhances the Sc(3+) ion-coupled electron transfer from DMA derivatives to [Fe(IV)(O)(N4Py)](2+), whereas binding of Sc(3+) to DMA derivatives retards the electron-transfer reaction. The complicated kinetics of the Sc(3+) ion-coupled electron transfer from DMA derivatives to [Fe(IV)(O)(N4Py)](2+) are analyzed by competition between binding of Sc(3+) to DMA derivatives and to [Fe(IV)(O)(N4Py)](2+). The binding constants of Sc(3+) to DMA derivatives increase with the increase of the electron-donating ability of the para-substituent. The rate constants of Sc(3+) ion-coupled electron transfer from DMA derivatives to [Fe(IV)(O)(N4Py)](2+), which are estimated from the binding constants of Sc(3+) to DMA derivatives, agree well with those predicted from the driving force dependence of the rate constants of Sc(3+) ion-coupled electron transfer from one-electron reductants to [Fe(IV)(O)(N4Py)](2+). Thus, oxidative dimerization of DMA and N-demethylation of para-substituted DMA derivatives proceed via Sc(3+) ion-coupled electron transfer from DMA derivatives to [Fe(IV)(O)(N4Py)](2+).
Collapse
Affiliation(s)
- Jiyun Park
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | | | | | | | | | | |
Collapse
|
25
|
|
26
|
|
27
|
Kawashima T, Ohkubo K, Fukuzumi S. Radical Scavenging Reactivity of Catecholamine Neurotransmitters and the Inhibition Effect for DNA Cleavage. J Phys Chem B 2009; 114:675-80. [DOI: 10.1021/jp909314t] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Tomonori Kawashima
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| |
Collapse
|
28
|
Hadadzadeh H, Hosseinian SR, Fatemi SJA. Rhodium(III) and cadmium(II) complexes based on the polypyridyl ligand 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz). Polyhedron 2009. [DOI: 10.1016/j.poly.2009.05.072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
29
|
Fukuzumi S. Roles of Metal Ions in Controlling Bioinspired Electron-Transfer Systems. Metal Ion-Coupled Electron Transfer. PROGRESS IN INORGANIC CHEMISTRY 2009. [DOI: 10.1002/9780470440124.ch2] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
30
|
Fukuzumi S, Ohkubo K, Ortiz J, Gutiérrez AM, Fernández-Lázaro F, Sastre-Santos Á. Control of Photoinduced Electron Transfer in Zinc Phthalocyanine−Perylenediimide Dyad and Triad by the Magnesium Ion. J Phys Chem A 2008; 112:10744-52. [DOI: 10.1021/jp805464e] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Javier Ortiz
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Ana M. Gutiérrez
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Fernando Fernández-Lázaro
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Ángela Sastre-Santos
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| |
Collapse
|
31
|
Nokami T, Ohata K, Inoue M, Tsuyama H, Shibuya A, Soga K, Okajima M, Suga S, Yoshida JI. Iterative Molecular Assembly Based on the Cation-Pool Method. Convergent Synthesis of Dendritic Molecules. J Am Chem Soc 2008; 130:10864-5. [DOI: 10.1021/ja803487q] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Toshiki Nokami
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kousuke Ohata
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masafumi Inoue
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Hiroaki Tsuyama
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Akito Shibuya
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazuya Soga
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masayuki Okajima
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Seiji Suga
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| | - Jun-ichi Yoshida
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto 615-8510, Japan
| |
Collapse
|
32
|
Fukuzumi S, Kojima T. Control of redox reactivity of flavin and pterin coenzymes by metal ion coordination and hydrogen bonding. J Biol Inorg Chem 2008; 13:321-33. [DOI: 10.1007/s00775-008-0343-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Accepted: 01/11/2008] [Indexed: 11/30/2022]
|
33
|
Yuasa J, Fukuzumi S. OFF−OFF−ON Switching of Fluorescence and Electron Transfer Depending on Stepwise Complex Formation of a Host Ligand with Guest Metal Ions. J Am Chem Soc 2007; 130:566-75. [DOI: 10.1021/ja0748480] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Junpei Yuasa
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan
| |
Collapse
|
34
|
Maruyama T, Mizuno Y, Shimizu I, Suga S, Yoshida JI. Reactions of a N-Acyliminium Ion Pool with Benzylsilanes. Implication of a Radical/Cation/Radical Cation Chain Mechanism Involving Oxidative C−Si Bond Cleavage. J Am Chem Soc 2007; 129:1902-3. [PMID: 17260999 DOI: 10.1021/ja068589a] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomokazu Maruyama
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | | | | | | | | |
Collapse
|
35
|
Ohkubo K, Ortiz J, Martín-Gomis L, Fernández-Lázaro F, Sastre-Santos A, Fukuzumi S. Fullerene acting as an electron donor in a donor–acceptor dyad to attain the long-lived charge-separated state by complexation with scandium ion. Chem Commun (Camb) 2007:589-91. [PMID: 17264900 DOI: 10.1039/b612613h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A long-lived charge-separated (CS) state of fullerene-trinitrofluorenone linked dyad in which fullerene acts as an electron donor is formed by photoinduced electron transfer from C60 to TNF in the presence of Sc(OTf)3; the CS lifetime is determined as 23 ms in PhCN at 298 K.
Collapse
Affiliation(s)
- Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka, 565-0871, Japan
| | | | | | | | | | | |
Collapse
|
36
|
Manda S, Nakanishi I, Ohkubo K, Yakumaru H, Matsumoto KI, Ozawa T, Ikota N, Fukuzumi S, Anzai K. Nitroxyl radicals: electrochemical redox behaviour and structure–activity relationships. Org Biomol Chem 2007; 5:3951-5. [DOI: 10.1039/b714765a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
37
|
Yuasa J, Fukuzumi S. An OFF−OFF−ON Fluorescence Sensor for Metal Ions in Stepwise Complex Formation of 2,3,5,6-Tetrakis(2-pyridyl)pyrazine with Metal Ions. J Am Chem Soc 2006; 128:15976-7. [PMID: 17165717 DOI: 10.1021/ja066381j] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fluorescence intensity of 2,3,5,6-tetrakis(2-pyridyl)pyrazine (TPPZ) begins to increase at concentrations of metal ions (Mn+) above the 1:2 ratio of metal ion concentration to the initial concentration of TPPZ ([Mn+]/[TPPZ]0 > 0.5), when a 2:1 complex of TPPZ with Mn+ [(TPPZ)2-Mn+] is converted to a 1:1 complex of TPPZ with Mn+ (TPPZ-Mn+), which exhibits strong fluorescence.
Collapse
Affiliation(s)
- Junpei Yuasa
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan
| | | |
Collapse
|
38
|
Fukuzumi S. Proton-Coupled Electron Transfer of Unsaturated Fatty Acids and Mechanistic Insight into Lipoxygenase. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690223] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
39
|
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: 41] [Impact Index Per Article: 2.3] [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.
Collapse
Affiliation(s)
- Atsuo Kobayashi
- Graduate School of Science and Engineering, Saitama University, Japan
| | | | | | | | | | | | | |
Collapse
|
40
|
Fukuzumi S. Bioinspired Electron-Transfer Systems and Applications. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2006. [DOI: 10.1246/bcsj.79.177] [Citation(s) in RCA: 188] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
41
|
Kitaguchi H, Ohkubo K, Ogo S, Fukuzumi S. Electron-Transfer Oxidation Properties of Unsaturated Fatty Acids and Mechanistic Insight into Lipoxygenases. J Phys Chem A 2006; 110:1718-25. [PMID: 16451000 DOI: 10.1021/jp054648f] [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: 11/28/2022]
Abstract
Rate constants of photoinduced electron-transfer oxidation of unsaturated fatty acids with a series of singlet excited states of oxidants in acetonitrile at 298 K were examined and the resulting electron-transfer rate constants (k(et)) were evaluated in light of the free energy relationship of electron transfer to determine the one-electron oxidation potentials (E(ox)) of unsaturated fatty acids and the intrinsic barrier of electron transfer. The k(et) values of linoleic acid with a series of oxidants are the same as the corresponding k(et) values of methyl linoleate, linolenic acid, and arachidonic acid, leading to the same E(ox) value of linoleic acid, methyl linoleate, linolenic acid, and arachidonic acid (1.76 V vs SCE), which is significantly lower than that of oleic acid (2.03 V vs SCE) as indicated by the smaller k(et) values of oleic acid than those of other unsaturated fatty acids. The radical cation of linoleic acid produced in photoinduced electron transfer from linoleic acid to the singlet excited state of 10-methylacridinium ion as well as that of 9,10-dicyanoanthracene was detected by laser flash photolysis experiments. The apparent rate constant of deprotonation of the radical cation of linoleic acid was determined as 8.1 x 10(3) s(-1). In the presence of oxygen, the addition of oxygen to the deprotonated radical produces the peroxyl radical, which has successfully been detected by ESR. No thermal electron transfer or proton-coupled electron transfer has occurred from linoleic acid to a strong one-electron oxidant, Ru(bpy)3(3+) (bpy = 2,2'-bipyridine) or Fe(bpy)3(3+). The present results on the electron-transfer and proton-transfer properties of unsaturated fatty acids provide valuable mechanistic insight into lipoxygenases to clarify the proton-coupled electron-transfer process in the catalytic function.
Collapse
Affiliation(s)
- Hironori Kitaguchi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan
| | | | | | | |
Collapse
|
42
|
Heinz B, Schmidt B, Root C, Satzger H, Milota F, Fierz B, Kiefhaber T, Zinth W, Gilch P. On the unusual fluorescence properties of xanthone in water. Phys Chem Chem Phys 2006; 8:3432-9. [PMID: 16855722 DOI: 10.1039/b603560d] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photo-excited xanthone is known to undergo ultrafast intersystem crossing (ISC) in the 1 ps time domain. Correspondingly, its fluorescence quantum yield in most solvents is very small ( approximately 10(-4)). Surprisingly, the quantum yield in water is 100 times larger, while ISC is still rapid ( approximately 1 ps), as seen by ultrafast pump probe absorption spectroscopy. Temperature dependent steady state and time resolved fluorescence experiments point to a delayed fluorescence mechanism, where the triplet (3)npi* state primarily accessed by ISC is nearly isoenergetic with the photo-excited (1)pipi* state. The delayed fluorescence of xanthone in water decays with a time constant of 700 ps, apparently by internal conversion between the (3)npi* state and the lowest lying triplet state (3)pipi*.
Collapse
Affiliation(s)
- B Heinz
- Department für Physik, Ludwig-Maximilians-Universität, Oettingenstr. 67, D-80538, München, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Zarkadis AK, Georgakilas V, Perdikomatis GP, Trifonov A, Gurzadyan GG, Skoulika S, Siskos MG. Triplet- vs. singlet-state imposed photochemistry. The role of substituent effects on the photo-Fries and photodissociation reaction of triphenylmethyl silanes. Photochem Photobiol Sci 2005; 4:469-80. [PMID: 15920631 DOI: 10.1039/b502089a] [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: 11/21/2022]
Abstract
The photochemistry of three structurally very similar triphenylmethylsilanes 1, 2, 3 [p-X-C(6)H(4)-CPh(2)-SiMe(3): X = PhCO, 1; H, ; Ph(OCH(2)CH(2)O)C, 3] is described by means of 248 and 308 nm nanosecond laser flash photolysis (ns-LFP), femtosecond LFP, EPR spectroscopy, emission spectroscopy (fluorescence, phosphorescence), ns-pulse radiolysis (ns-PR), photoproduct analysis studies in MeCN, and X-ray crystallographic analysis of the two key-compounds 1 and 2. The photochemical behavior of 1, 2 and 3 is discussed and compared with that of a fourth one, 4, bearing on the p-position an amino group (X = Me(2)N) and whose detailed photochemistry we reported earlier (J. Org. Chem., 2000, 65, 4274-4280). Silane 1 undergoes on irradiation with 248 and 308 nm laser light a fast photodissociation of the C-Si bond giving the p-(benzoyl)triphenylmethyl radical (1*) with a rate constant of k(diss)= 3 x 10(7) s(-1). The formation of 1* is a one-quantum process and takes place via the carbonyl triplet excited state with high quantum yield (Phi(rad)= 0.9); the intervention of the triplet state is clearly demonstrated through the phosphorescence spectrum and quenching experiments with ferrocene (k(q)= 9.3 x 10(9) M(-1) s(-1)), Et(3)N (1.1 x 10(9) M(-1) s(-1)), and styrene (3.1 x 10(9) M(-1) s(-1)) giving quenching rate constants very similar to those of benzophenone. For comparative reasons radical 1* was generated independently from p-(benzoyl)triphenylmethyl bromide via pulse radiolysis in THF and its absorption coefficient at lambda(max)= 340 nm was determined ([epsilon]= 27770 M(-1) cm(-1)). We found thus that the p-PhCO-derivative 1 behaves similar to the p-Me(2)N one (the latter giving the p-(dimethylamino)triphenylmethyl radical with Phi(rad)= 0.9), irrespective of their completely different ground state electronic properties. In contrast, compounds 2, 3 that bear only the aromatic chromophore give by laser or lamp irradiation both, (i) radical products [Ph(3)C* and p-Ph(OCH(2)CH(2)O)C-C(6)H(4)-C(*)Ph(2), respectively] after dissociation of the central C-Si bond (Phi(rad)= 0.16), and (ii) persistent photo-Fries rearrangement products (of the type of 5-methylidene-6-trimethylsilyl-1,3-cyclohexadiene) absorbing at 300-450 nm and arising from a 1,3-shift of the SiMe(3) group from the benzylic to the ortho-position of the aromatic ring (Phi approximately 0.85 for 2). Using fs-LFP on 2 we showed that the S(1) state recorded at 100 fs after the pulse decays on a time scale of 500 fs giving Ph(3)C* through C-Si bond dissociation. In a second step and within the next 10 ps trityl radicals either escape from the solvent cage (the quantum yield of Ph(3)C* formation Phi(rad)= 0.16 was measured with ns-LFP), or undergo in-cage recombination to photo-Fries products. Thus, singlet excited states (S(1)) of the aromatic organosilanes (2, 3) prefer photo-Fries rearrangement products, while triplet excited states (1, 4) favor free radicals. Both reactions proceed via a common primary photodissociation step (C-Si bond homolysis) and differentiate obviously in the multiplicity of the resulting geminate radical pairs; singlet radical pairs give preferably photo-Fries products following an in-cage recombination, while triplet radical pairs escape the solvent cage (MeCN). The results demonstrate the crucial role which is played by the chromophore which prescribes in a sense, (i) the multiplicity of the intervening excited state and consequently that of the resulting geminate radical pair, and (ii) the dominant reaction path to be followed: the benzophenone- and anilino-chromophore present in silanes 1 and 4, respectively, impose effective intersystem crossing transitions (k(isc)= 10(11) s(-1) and 6 x 10(8) s(-1), respectively) leading to triplet states and finally to free radical products, while the phenyl chromophore in 2 and 3, possessing ineffective isc (k(isc)= 6 x 10(6) s(-1)) leads to photo-Fries product formation via the energetic high lying S(1) state [approximately 443 kJ mol(-1)(106 kcal mol(-1))].
Collapse
|
44
|
Okamoto K, Ohkubo K, Kadish KM, Fukuzumi S. Remarkable Accelerating Effects of Ammonium Cations on Electron-Transfer Reactions of Quinones by Hydrogen Bonding with Semiquinone Radical Anions. J Phys Chem A 2004. [DOI: 10.1021/jp046078+] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
45
|
Hayamizu T, Maeda H, Mizuno K. Diastereoselective protonation on radical anions of electron-deficient alkenes via photoinduced electron transfer. J Org Chem 2004; 69:4997-5004. [PMID: 15255727 DOI: 10.1021/jo0496953] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diastereoselective protonations in the photoinduced electron transfer (PET) reactions of 1,1-dicyanoethene derivatives (1a-e) by use of organosilicon compounds such as allyltrimethylsilane (2) and benzyltrimethylsilane (5) are described. Irradiation of an acetonitrile-acetic acid solution containing 4-tert-butylcyclohexylidenepropanedinitrile (1a) and an excess of 2 in the presence of phenanthrene (Phen) as a sensitizer afforded reduction and allylated products (3a, 4a) in 63:37 and 57:43 ratios in a less regioselective manner. Photoreactions of 3,3,5-trimethylcyclohexylidenepropanedinitrile (1b), 2-methylcyclohexylidenepropanedinitrile (1c), bicyclo[2.2.1]-2-heptylidenepropanedinitrile (1d), and 1,7,7-trimethylbicyclo[2.2.1]-2-heptylidenepropanedinitrile (1e) with 2 showed higher diastereoselectivity via the PET process. Similar diastereoselectivities were obtained in the Phen-sensitized photoreaction of 1a-e with 5. When 2,4,6-trimethylpyridinium tosylate (7) was used as a proton source in place of acetic acid, the product ratios were substantially changed in several cases. From these results, steric and torsional effects have been postulated as important factors for the control of the diastereoselectivity in these PET reactions.
Collapse
Affiliation(s)
- Tomoo Hayamizu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
| | | | | |
Collapse
|
46
|
Yuasa J, Ohkubo K, Guldi DM, Fukuzumi S. Drastic Changes in the Lifetime and Electron Transfer and Energy Transfer Reactivity of the Triplet Excited State of p-Benzoquinone by Complex Formation with Scandium Ion Salts. J Phys Chem A 2004. [DOI: 10.1021/jp047748e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Junpei Yuasa
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Dirk M. Guldi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| |
Collapse
|
47
|
Fukuzumi S, Yuasa J, Satoh N, Suenobu T. Scandium Ion-Promoted Photoinduced Electron Transfer from Electron Donors to Acridine and Pyrene. Essential Role of Scandium Ion in Photocatalytic Oxygenation of Hexamethylbenzene. J Am Chem Soc 2004; 126:7585-94. [PMID: 15198606 DOI: 10.1021/ja031649h] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoinduced electron transfer from a variety of electron donors including alkylbenzenes to the singlet excited state of acridine and pyrene is accelerated significantly by the presence of scandium triflate [Sc(OTf)(3)] in acetonitrile, whereas no photoinduced electron transfer from alkylbenzenes to the singlet excited state of acridine or pyrene takes place in the absence of Sc(OTf)(3). The rate constants of the Sc(OTf)(3)-promoted photoinduced electron-transfer reactions (k(et)) of acridine to afford the complex between acridine radical anion and Sc(OTf)(3) remain constant under the conditions such that all the acridine molecules form the complex with Sc(OTf)(3). In contrast to the case of acridine, the k(et) value of the Sc(OTf)(3)-promoted photoinduced electron transfer of pyrene increases with an increase in concentration of Sc(OTf)(3) to exhibit first-order dependence on [Sc(OTf)(3)] at low concentrations, changing to second-order dependence at high concentrations. The first-order and second-order dependence of k(et) on [Sc(OTf)(3)] is ascribed to the 1:1 and 1:2 complexes formation between pyrene radical anion and Sc(OTf)(3). The positive shifts of the one-electron redox potentials for the couple between the singlet excited state and the ground-state radical anion of acridine and pyrene in the presence of Sc(OTf)(3) as compared to those in the absence of Sc(OTf)(3) have been determined by adapting the free energy relationship for the photoinduced electron-transfer reactions. The Sc(OTf)(3)-promoted photoinduced electron transfer from hexamethylbenzene to the singlet excited state of acridine or pyrene leads to efficient oxygenation of hexamethylbenzene to produce pentamethylbenzyl alcohol which is further oxygenated under prolonged photoirradiation of an O(2)-saturated acetonitrile solution of hexamethylbenzene in the presence of acridine or pyrene which acts as a photocatalyst together with Sc(OTf)(3). The photocatalytic oxygenation mechanism has been proposed based on the studies on the quantum yields, the fluorescence quenching, and direct detection of the reaction intermediates by ESR and laser flash photolysis.
Collapse
Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan.
| | | | | | | |
Collapse
|
48
|
Budyka MF, Zyubina TS, Zarkadis AK. Quantum chemical study of the Si–C bond photodissociation in benzylsilane derivatives: a specific ‘excited-state’ silicon effect. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.theochem.2003.08.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
49
|
Ohkubo K, Menon SC, Orita A, Otera J, Fukuzumi S. Quantitative evaluation of Lewis acidity of metal ions with different ligands and counterions in relation to the promoting effects of Lewis acids on electron transfer reduction of oxygen. J Org Chem 2003; 68:4720-6. [PMID: 12790575 DOI: 10.1021/jo034258u] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The g(zz) values of ESR spectra of superoxide (O(2)(.-) complexes of metal ion salts acting as Lewis acids with different ligands and counterions were determined in acetonitrile at 143 K. The binding energies (DeltaE) of (O(2)(.-)/Lewis acid complexes have been evaluated from deviation of the g(zz) values from the free spin value. The DeltaE value is quite sensitive to the difference in the counterions and ligands of metal ion salts acting as Lewis acids. On the other hand, the fluorescence maxima of the singlet excited states of 10-methylacridone/Lewis acid complexes are red-shifted as compared with that of 10-methylacridone, and the relative emission energies (Deltahnu(f)) vary significantly depending on the Lewis acidity of metal ion salts with different counterions and ligands. The promoting effects of Lewis acids were also examined on electron transfer from cobalt(II) tetraphenylporphyrin to oxygen in acetonitrile at 298 K, which does not occur in the absence of Lewis acids under otherwise the same experimental conditions. Both DeltaE and Deltahnu(f) values are well correlated with the promoting effects of Lewis acids on the electron transfer reduction of oxygen. Such correlations indicate that DeltaE and Deltahnu(f) values can be used as quantitative measures of Lewis acidity of metal ion salts with different ligands and counterions. The Lewis acidity thus determined can also be applied to predict the promoting effects of Lewis acids on organic synthesis.
Collapse
Affiliation(s)
- Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST Science and Technology Corporation, Suita, Osaka 565-0871, Japan
| | | | | | | | | |
Collapse
|
50
|
Okamoto K, Imahori H, Fukuzumi S. Metal ion-promoted intramolecular electron transfer in a ferrocene-naphthoquinone linked dyad. Continuous change in driving force and reorganization energy with metal ion concentration. J Am Chem Soc 2003; 125:7014-21. [PMID: 12783556 DOI: 10.1021/ja034831r] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermal intramolecular electron transfer from the ferrocene (Fc) to naphthoquinone (NQ) moiety occurs efficiently by the addition of metal triflates (M(n)()(+): Sc(OTf)(3), Y(OTf)(3), Eu(OTf)(3)) to an acetonitrile solution of a ferrocene-naphthoquinone (Fc-NQ) linked dyad with a flexible methylene and an amide spacer, although no electron transfer takes place in the absence of M(n)()(+). The resulting semiquinone radical anion (NQ(*)(-)) is stabilized by the strong binding of M(n)()(+) with one carbonyl oxygen of NQ(*)(-)( )()as well as hydrogen bonding between the amide proton and the other carbonyl oxygen of NQ(*)(-). The high stability of the Fc(+)()-NQ(*)(-)/M(n)()(+)() complex allows us to determine the driving force of electron transfer by the conventional electrochemical method. The one-electron reduction potential of the NQ moiety of Fc-NQ is shifted to a positive direction with increasing concentration of M(n)()(+), obeying the Nernst equation, whereas the one-electron oxidation potential of the Fc moiety remains the same. The driving force dependence of the observed rate constant (k(ET)) of M(n)()(+)-promoted intramolecular electron transfer is well evaluated in light of the Marcus theory of electron transfer. The driving force of electron transfer increases with increasing concentration of M(n)()(+) [M(n)()(+)], whereas the reorganization energy of electron transfer decreases with increasing [M(n)()(+)] from a large value which results from the strong binding between NQ(*)(-) and M(n)()(+).
Collapse
Affiliation(s)
- Ken Okamoto
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, CREST, Japan Science and Technology Corporation, Suita, Osaka 565-0871, Japan
| | | | | |
Collapse
|