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Abou-Hatab S, Matsika S. Excited state hydrogen or proton transfer pathways in microsolvated n-cyanoindole fluorescent probes. Phys Chem Chem Phys 2024; 26:4511-4523. [PMID: 38240574 DOI: 10.1039/d3cp04844f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The sensitivity of the fluorescence properties of n-cyanoindole (n-CNI) fluorescent probes to the microenvironment makes them potential reporters of protein conformation and hydration. The fluorescence intensity of 5-CNI, 6-CNI, and 7-CNI is quenched when exposed to water solvent whereas substitution on position 4 of indoles dramatically increases it. A potential mechanism for this sensitivity to water may be similar to that found in indole. The fluorescence of indole is found to be quenched when interacting with water and ammonia solvent molecules via radiationless decay through an S1 (πσ*)/S0 conical intersection caused by excited state proton or hydrogen transfer to the solvent molecules. In this study we examine this fluorescence quenching mechanism along the N-H bond stretch of n-CNI probes using water cluster models and quantum mechanical calculations of the excited states. We find that n-CNI-(H2O)1-2 clusters form cyclic or non-cyclic structures via hydrogen bonds which lead to different photochemical reaction paths that can potentially quench the fluorescence by undergoing internal conversion from S1 to S0. However, the existence of a high energy barrier along the potential energy surface of the S1 state in most cases prevents this from occurring. We show that substitution on position 4 leads to the highest energy barrier that prevents the fluorophore from accessing these non-radiative channels, in agreement with its high intensity. We also find that the energy barrier in the S1 state of non-cyclic 5-CNI-(H2O)1-2 excited complexes decreases as the number of water molecules increases, which suggests great sensitivity of the fluorescence quenching on the aqueous environment.
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Min A, Kim J, Moon CJ, Ahn A, Park J, Choi MY. Spectroscopic and theoretical studies of jet‐cooled 3‐cyanoindole ammonia clusters in the gas phase. B KOREAN CHEM SOC 2022. [DOI: 10.1002/bkcs.12502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Ahreum Min
- Core‐Facility Center for Photochemistry & Nanomaterials Gyeongsang National University Jinju Republic of Korea
| | - Jiwon Kim
- Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences Gyeongsang National University Jinju Republic of Korea
| | - Cheol Joo Moon
- Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences Gyeongsang National University Jinju Republic of Korea
| | - Ahreum Ahn
- Center for Supercomputing Applications Korea Institute of Science and Technology Information Daejeon Republic of Korea
| | - Juhyeon Park
- Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences Gyeongsang National University Jinju Republic of Korea
| | - Myong Yong Choi
- Core‐Facility Center for Photochemistry & Nanomaterials Gyeongsang National University Jinju Republic of Korea
- Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences Gyeongsang National University Jinju Republic of Korea
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Lee GW. Observation of vibronic emission spectrum of jet-cooled 3-chloro-4-fluorobenzyl radical. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 261:120001. [PMID: 34098481 DOI: 10.1016/j.saa.2021.120001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/19/2021] [Accepted: 05/23/2021] [Indexed: 06/12/2023]
Abstract
We observed the vibronic emission spectrum of 3-chloro-4-fluorobenzyl radical using a corona-excited supersonic jet expansion (CESE) from the precursor 3-chloro-4-fluorotoluene. From an analysis of the observed spectrum, we investigate the formation of the 3-chloro-4-fluorobenzyl and 4-fluorobenzyl radicals and explained the reaction paths with an ab initio study. The D1 → D0 transition energy and the frequencies of vibrational mode of the 3-chloro-4-fluorobenzyl radical were determined with a Franck-Condon simulation from density functional theory calculations in the D0 and D1 states.
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Affiliation(s)
- Gi Woo Lee
- Inorganic Material Team, Chemical Development Group, Dongwoo Fine-chem, Iksansi, Jeonrabukdo, Republic of Korea.
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Henrichs C, Zimmermann S, Hebestreit ML, Schmitt M. Excited state structure of isolated 2-cyanoindole and the binary 2-cyanoindole-(H2O)1 cluster from a combined Franck-Condon and rotational constants fit. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130055] [Citation(s) in RCA: 1] [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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Hebestreit ML, Lartian H, Henrichs C, Kühnemuth R, Meerts WL, Schmitt M. Excited state dipole moments and lifetimes of 2-cyanoindole from rotationally resolved electronic Stark spectroscopy. Phys Chem Chem Phys 2021; 23:10196-10204. [PMID: 33951126 DOI: 10.1039/d1cp00097g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The permanent dipole moments of 2-cyanoindole (cyanoindole = CNI) in its ground and lowest excited singlet states have been determined from rotationally resolved electronic Stark spectroscopy under jet-cooled conditions. From the orientation of the transition dipole moment and the geometry changes upon electronic excitation the lowest excited singlet state could be shown to be of Lb-symmetry. The general statement, that the La-state has the larger permanent dipole moment of the two lowest excited singlet states, will be challenged in this contribution. On the basis of the different electronic nature of the first excited singlet state the behavior of 2-, 3-, 4- and 5-CNI is discussed. The excited state lifetime of isolated 2-CNI in the gas phase has been determined to be 9.4 ns. This value is compared to the excited state lifetime in ethyl acetate solution of 2.6 ns, which was quantified with a Strickler-Berg analysis. Using water as solvent shortens the 2-CNI lifetime to <40 ps. The reason for this drastic shortening is discussed in detail. Additionally, the rotationally resolved electronic spectrum of 2-CNI(1-d1) has been measured and analyzed.
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Affiliation(s)
- Marie-Luise Hebestreit
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
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Excited state structure of isolated 4-cyanoindole from a combined Franck-Condon and rotational constants analysis†. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Huh CS. Observation of vibronic emission spectrum of jet-cooled 4-chloro-m-xylyl radical. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.136694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hebestreit ML, Schneider M, Lartian H, Betz V, Heinrich M, Lindic M, Choi MY, Schmitt M. Structures, dipole moments and excited state lifetime of isolated 4-cyanoindole in its ground and lowest electronically excited singlet states. Phys Chem Chem Phys 2019; 21:14766-14774. [PMID: 31222195 DOI: 10.1039/c9cp01618j] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rotationally resolved electronic spectrum of 4-cyanoindole and some N-D and C-D deuterated isotopologues has been measured and analyzed. Dipole moments in the ground and electronically excited state have been determined, using electronic Stark spectroscopy. From the geometry changes upon excitation, orientation of the transition dipole moment, and the values for the permanent dipole moments, the lowest excited singlet state could be shown to be of La symmetry. The excited state lifetime of isolated 4-cyanoindole has been determined to be 11 ns, while for the ringdeuterated isotopologues lifetimes between 5 and 6 ns have been found. The different behavior of 3-, 4-, and 5-cyanoindole is discussed on the basis of the different electronic nature of the electronically excited singlet states.
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Affiliation(s)
- Marie-Luise Hebestreit
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Michael Schneider
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Hilda Lartian
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Vivienne Betz
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Michael Heinrich
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Mirko Lindic
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Myong Yong Choi
- Department of Chemistry (BK21+) and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Michael Schmitt
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
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Schneider M, Hebestreit ML, Lindic MM, Parsian H, Torres-Boy AY, Álvarez-Valtierra L, Meerts WL, Kühnemuth R, Schmitt M. Rotationally resolved electronic spectroscopy of 3-cyanoindole and the 3-cyanoindole-water complex. Phys Chem Chem Phys 2018; 20:23441-23452. [PMID: 30182125 DOI: 10.1039/c8cp04020f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rotationally resolved electronic spectra of the origin bands of 3-cyanoindole, 3-cyanoindole(d1), and the 3-cyanoindole-(H2O)1 cluster have been measured and analyzed using evolutionary algorithms. For the monomer, permanent dipole moments of 5.90 D for the ground state, and of 5.35 D for the lowest excited singlet state have been obtained from electronic Stark spectroscopy. The orientation of the transition dipole moment is that of an 1Lb state for the monomer. The water moiety in the water cluster could be determined to be trans-linearly bound to the NH group of 3-cyanoindole, with an NHO hydrogen bond length of 201.9 pm in the electronic ground state. Like the 3-cyanoindole monomer, the 3-cyanoindole-water cluster also shows an 1Lb-like excited singlet state. The excited state lifetime of isolate 3-cyanoindole in the gas phase has been determined to be 9.8 ns, and that of 3-cyanoindole(d1) has been found to be 14.8 ns, while that of the 1 : 1 water cluster is considerably shorter (3.6 ns). The excited state lifetime of 3-cyanoindole(d1) in D2O solution has been found to be smaller than 20 ps.
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Affiliation(s)
- Michael Schneider
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Marie-Luise Hebestreit
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Mirko Matthias Lindic
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - Hilda Parsian
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
| | - América Yareth Torres-Boy
- División de Ciencias e Ingenierías, Universidad de Guanajuato-Campus León, León, Guanajuato 37150, Mexico
| | - Leonardo Álvarez-Valtierra
- División de Ciencias e Ingenierías, Universidad de Guanajuato-Campus León, León, Guanajuato 37150, Mexico
| | - W Leo Meerts
- Radboud University, Institute for Molecules and Materials, Felix Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - Ralf Kühnemuth
- Heinrich-Heine-Universität, Lehrstuhl für Molekulare Physikalische Chemie, D-40225 Düsseldorf, Germany
| | - Michael Schmitt
- Heinrich-Heine-Universität, Institut für Physikalische Chemie I, D-40225 Düsseldorf, Germany.
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Min A, Moon CJ, Ahn A, Lee JH, Kim SK, Choi MY. Electronic and vibrational spectroscopic studies of jet-cooled 5-cyanoindole and its water clusters, 5CI–(H2O) , (n= 0–2). Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.06.008] [Citation(s) in RCA: 5] [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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Ahn A, Min A, Moon CJ, Lee JH, Lee SJ, Warashina T, Ishiuchi SI, Fujii M, Choi MY. Spectroscopic study of jet-cooled indole-3-carbinol by laser desorption technique: Franck–Condon simulations and anharmonic calculations. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.08.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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