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Hou Z, Guan J, Peng J, Li X, Yu Z, Zheng J. Double crossing conical intersections and anti-Vavilov fluorescence in tetraphenyl ethylene. J Chem Phys 2022; 156:144302. [DOI: 10.1063/5.0082679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Conical intersections (CIs) provide effective fast nonradiative decay pathways for electronic excitation, which can significantly influence molecular photoluminescence properties. However, in many cases, crossing a CI does not have direct observables, making studies of CIs experimentally challenging. Herein, the theoretically predicted double CIs by cis–trans twisting and cyclization in tetraphenyl ethylene, a well-known aggregation-induced emission molecule, are investigated with excitation dependent ultrafast UV/IR spectroscopy and fluorescence. Both the fluorescence quantum yield and the efficiency of cyclization are found to be smaller with a shorter excitation wavelength. An abrupt change occurs at about 300–310 nm. The results imply that crossing the twisting CI has a larger barrier than the cyclization CI, and the cis–trans twisting motion is probably involved with large solvation reorganization.
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Affiliation(s)
- Zhuowei Hou
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Jianxin Guan
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Jie Peng
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Xinmao Li
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Zhihao Yu
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
| | - Junrong Zheng
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, People’s Republic of China
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Su D, Kabir MP, Orozco-Gonzalez Y, Gozem S, Gadda G. Fluorescence Properties of Flavin Semiquinone Radicals in Nitronate Monooxygenase. Chembiochem 2019; 20:1646-1652. [PMID: 30748074 DOI: 10.1002/cbic.201900016] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Indexed: 11/09/2022]
Abstract
Fluorescent cofactors like flavins can be exploited to probe their local environment with spatial and temporal resolution. Although the fluorescence properties of the oxidized and two-electron-reduced states of flavins have been studied extensively, this is not the case for the one-electron-reduced state. Both the neutral and anionic semiquinones have proven particularly challenging to examine, as they are unstable in solution and are transient, short-lived species in many catalytic cycles. Here, we report that the nitronate monooxygenase (NMO) from Pseudomonas aeruginosa PAO1 is capable of stabilizing both semiquinone forms anaerobically for hours, thus enabling us to study their spectroscopy in a constant protein environment. We found that in the active site of NMO, the anionic semiquinone exhibits no fluorescence, whereas the neutral semiquinone radical shows a relatively strong fluorescence, with a behavior that violates the Kasha-Vavilov rule. These fluorescence properties are discussed in the context of time-dependent density functional theory calculations, which reveal low-lying dark states in both systems.
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Affiliation(s)
- Dan Su
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Mohammad Pabel Kabir
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Yoelvis Orozco-Gonzalez
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Samer Gozem
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, 50 Decatur St. SE, Atlanta, GA, 30302, USA.,Department of Biology, Georgia State University, 100 Piedmond Ave., Atlanta, GA, 30303, USA.,Center for Diagnostics and Therapeutics, Georgia State University, P.O. Box 5090, Atlanta, GA, 30303, USA.,Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, 30302, USA
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Lee J, Müller F, Visser AJWG. The Sensitized Bioluminescence Mechanism of Bacterial Luciferase. Photochem Photobiol 2018; 95:679-704. [PMID: 30485901 DOI: 10.1111/php.13063] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/17/2018] [Indexed: 11/27/2022]
Abstract
After more than one-half century of investigations, the mechanism of bioluminescence from the FMNH2 assisted oxygen oxidation of an aliphatic aldehyde on bacterial luciferase continues to resist elucidation. There are many types of luciferase from species of bioluminescent bacteria originating from both marine and terrestrial habitats. The luciferases all have close sequence homology, and in vitro, a highly efficient light generation is obtained from these natural metabolites as substrates. Sufficient exothermicity equivalent to the energy of a blue photon is available in the chemical oxidation of the aldehyde to the corresponding carboxylic acid, and a luciferase-bound FMNH-OOH is a key player. A high energy species, the source of the exothermicity, is unknown except that it is not a luciferin cyclic peroxide, a dioxetanone, as identified in the pathway of the firefly and the marine bioluminescence systems. Besides these natural substrates, variable bioluminescence properties are found using other reactants such as flavin analogs or aldehydes, but results also depend on the luciferase type. Some rationalization of the mechanism has resulted from spatial structure determination, NMR of intermediates and dynamic optical spectroscopy. The overall light path appears to fall into the sensitized class of chemiluminescence mechanism, distinct from the dioxetanone types.
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Affiliation(s)
- John Lee
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA
| | | | - Antonie J W G Visser
- Laboratory of Biochemistry Microspectroscopy Centre, Wageningen University, Wageningen, The Netherlands
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Demchenko AP, Tomin VI, Chou PT. Breaking the Kasha Rule for More Efficient Photochemistry. Chem Rev 2017; 117:13353-13381. [DOI: 10.1021/acs.chemrev.7b00110] [Citation(s) in RCA: 210] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Alexander P. Demchenko
- Palladin
Institute of Biochemistry, National Academy of Sciences of Ukraine, 9 Leontovicha Street, Kyiv 01030, Ukraine
| | - Vladimir I. Tomin
- Institute
of Physics, Pomeranian University in Słupsk, ul. Arciszewskiego, 22b, Słupsk 76-200, Poland
| | - Pi-Tai Chou
- Department
of Chemistry, National Taiwan University, 1 Roosevelt Road Section 4, Taipei 106, Taiwan
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Luo Y, Liu YJ. Bioluminophore and Flavin Mononucleotide Fluorescence Quenching of Bacterial Bioluminescence-A Theoretical Study. Chemistry 2016; 22:16243-16249. [PMID: 27665749 DOI: 10.1002/chem.201603314] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Indexed: 02/02/2023]
Abstract
Bacterial bioluminescence with continuous glow has been applied to the fields of environmental toxin monitoring, drug screening, and in vivo imaging. Nonetheless, the chemical form of the bacterial bioluminophore is still a bone of contention. Flavin mononucleotide (FMN), one of the light-emitting products, and 4a-hydroxy-5-hydro flavin mononucleotide (HFOH), an intermediate of the chemical reactions, have both been assumed candidates for the light emitter because they have similar molecular structures and fluorescence wavelengths. The latter is preferred in experiments and was assigned in our previous density functional study. HFOH displays weak fluorescence in solutions, but exhibits strong bioluminescence in the bacterial luciferase. FMN shows the opposite behavior; its fluorescence is quenched when it is bound to the luciferase. This is the first example of flavin fluorescence quenching observed in bioluminescent systems and is merely an observation, both the quenching mechanism and quencher are still unclear. Based on theoretical analysis of high-level quantum mechanics (QM), combined QM and molecular mechanics (QM/MM), and molecular dynamics (MD), this paper confirms that HFOH in its first singlet excited state is the bioluminophore of bacterial bioluminescence. More importantly, the computational results indicate that Tyr110 in the luciferase quenches the FMN fluorescence via an electron-transfer mechanism.
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Affiliation(s)
- Yanling Luo
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Ya-Jun Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China.
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Bu F, Duan R, Xie Y, Yi Y, Peng Q, Hu R, Qin A, Zhao Z, Tang BZ. Unusual Aggregation-Induced Emission of a Coumarin Derivative as a Result of the Restriction of an Intramolecular Twisting Motion. Angew Chem Int Ed Engl 2015; 54:14492-7. [PMID: 26439884 DOI: 10.1002/anie.201506782] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/31/2015] [Indexed: 12/22/2022]
Abstract
Aggregation-induced emission (AIE) is commonly observed for propeller-like luminogens with aromatic rotors and stators. Herein, we report that a coumarin derivative containing a seven-membered aliphatic ring (CD-7) but no rotors showed typical AIE characteristics, whereas its analogue with a five-membered aliphatic ring (CD-5) exhibited an opposite aggregation-caused quenching (ACQ) effect. Experimental and theoretical results revealed that a large aliphatic ring in CD-7 weakens structural rigidity and promotes out-of-plane twisting of the molecular backbone to drastically accelerate nonradiative excited-state decay, thus resulting in poor emission in solution. The restriction of twisting motion in aggregates blocks the nonradiative decay channels and enables CD-7 to fluoresce strongly. The results also show that AIE is a general phenomenon and not peculiar to propeller-like molecules. The AIE and ACQ effects can be switched readily by the modulation of molecular rigidity.
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Affiliation(s)
- Fan Bu
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)
| | - Ruihong Duan
- Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
| | - Yujun Xie
- Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
| | - Yuanping Yi
- Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
| | - Qian Peng
- Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China).
| | - Rongrong Hu
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)
| | - Anjun Qin
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China)
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China).
| | - Ben Zhong Tang
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China). .,Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China).
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Bu F, Duan R, Xie Y, Yi Y, Peng Q, Hu R, Qin A, Zhao Z, Tang BZ. Unusual Aggregation-Induced Emission of a Coumarin Derivative as a Result of the Restriction of an Intramolecular Twisting Motion. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506782] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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