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Intramolecular hydrogen bonding plays a crucial role in the photophysics and photochemistry of the GFP chromophore.
J Am Chem Soc. 2012 Jan 25; 134(3):1662-72.JA

Abstract

In commonly studied GFP chromophore analogues such as 4-(4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (PHBDI), the dominant photoinduced processes are cis-trans isomerization and subsequent S(1) → S(0) decay via a conical intersection characterized by a highly twisted double bond. The recently synthesized 2-hydroxy-substituted isomer (OHBDI) shows an entirely different photochemical behavior experimentally, since it mainly undergoes ultrafast intramolecular excited-state proton transfer, followed by S(1) → S(0) decay and ground-state reverse hydrogen transfer. We have chosen 4-(2-hydroxybenzylidene)-1H-imidazol-5(4H)-one (OHBI) to model the gas-phase photodynamics of such 2-hydroxy-substituted chromophores. We first use various electronic structure methods (DFT, TDDFT, CC2, DFT/MRCI, OM2/MRCI) to explore the S(0) and S(1) potential energy surfaces of OHBI and to locate the relevant minima, transition state, and minimum-energy conical intersection. These static calculations suggest the following decay mechanism: upon photoexcitation to the S(1) state, an ultrafast adiabatic charge-transfer induced excited-state intramolecular proton transfer (ESIPT) occurs that leads to the S(1) minimum-energy structure. Nearby, there is a S(1)/S(0) minimum-energy conical intersection that allows for an efficient nonadiabatic S(1) → S(0) internal conversion, which is followed by a fast ground-state reverse hydrogen transfer (GSHT). This mechanism is verified by semiempirical OM2/MRCI surface-hopping dynamics simulations, in which the successive ESIPT-GSTH processes are observed, but without cis-trans isomerization (which is a minor path experimentally with less than 5% yield). These gas-phase simulations of OHBI give an estimated first-order decay time of 476 fs for the S(1) state, which is larger but of the same order as the experimental values measured for OHBDI in solution: 270 fs in CH(3)CN and 230 fs in CH(2)Cl(2). The differences between the photoinduced processes of the 2- and 4-hydroxy-substituted chromophores are attributed to the presence or absence of intramolecular hydrogen bonding between the two rings.

Authors+Show Affiliations

Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22175658

Citation

Cui, Ganglong, et al. "Intramolecular Hydrogen Bonding Plays a Crucial Role in the Photophysics and Photochemistry of the GFP Chromophore." Journal of the American Chemical Society, vol. 134, no. 3, 2012, pp. 1662-72.
Cui G, Lan Z, Thiel W. Intramolecular hydrogen bonding plays a crucial role in the photophysics and photochemistry of the GFP chromophore. J Am Chem Soc. 2012;134(3):1662-72.
Cui, G., Lan, Z., & Thiel, W. (2012). Intramolecular hydrogen bonding plays a crucial role in the photophysics and photochemistry of the GFP chromophore. Journal of the American Chemical Society, 134(3), 1662-72. https://doi.org/10.1021/ja208496s
Cui G, Lan Z, Thiel W. Intramolecular Hydrogen Bonding Plays a Crucial Role in the Photophysics and Photochemistry of the GFP Chromophore. J Am Chem Soc. 2012 Jan 25;134(3):1662-72. PubMed PMID: 22175658.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Intramolecular hydrogen bonding plays a crucial role in the photophysics and photochemistry of the GFP chromophore. AU - Cui,Ganglong, AU - Lan,Zhenggang, AU - Thiel,Walter, Y1 - 2012/01/10/ PY - 2011/12/20/entrez PY - 2011/12/20/pubmed PY - 2012/5/23/medline SP - 1662 EP - 72 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 134 IS - 3 N2 - In commonly studied GFP chromophore analogues such as 4-(4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (PHBDI), the dominant photoinduced processes are cis-trans isomerization and subsequent S(1) → S(0) decay via a conical intersection characterized by a highly twisted double bond. The recently synthesized 2-hydroxy-substituted isomer (OHBDI) shows an entirely different photochemical behavior experimentally, since it mainly undergoes ultrafast intramolecular excited-state proton transfer, followed by S(1) → S(0) decay and ground-state reverse hydrogen transfer. We have chosen 4-(2-hydroxybenzylidene)-1H-imidazol-5(4H)-one (OHBI) to model the gas-phase photodynamics of such 2-hydroxy-substituted chromophores. We first use various electronic structure methods (DFT, TDDFT, CC2, DFT/MRCI, OM2/MRCI) to explore the S(0) and S(1) potential energy surfaces of OHBI and to locate the relevant minima, transition state, and minimum-energy conical intersection. These static calculations suggest the following decay mechanism: upon photoexcitation to the S(1) state, an ultrafast adiabatic charge-transfer induced excited-state intramolecular proton transfer (ESIPT) occurs that leads to the S(1) minimum-energy structure. Nearby, there is a S(1)/S(0) minimum-energy conical intersection that allows for an efficient nonadiabatic S(1) → S(0) internal conversion, which is followed by a fast ground-state reverse hydrogen transfer (GSHT). This mechanism is verified by semiempirical OM2/MRCI surface-hopping dynamics simulations, in which the successive ESIPT-GSTH processes are observed, but without cis-trans isomerization (which is a minor path experimentally with less than 5% yield). These gas-phase simulations of OHBI give an estimated first-order decay time of 476 fs for the S(1) state, which is larger but of the same order as the experimental values measured for OHBDI in solution: 270 fs in CH(3)CN and 230 fs in CH(2)Cl(2). The differences between the photoinduced processes of the 2- and 4-hydroxy-substituted chromophores are attributed to the presence or absence of intramolecular hydrogen bonding between the two rings. SN - 1520-5126 UR - https://www.unboundmedicine.com/medline/citation/22175658/Intramolecular_hydrogen_bonding_plays_a_crucial_role_in_the_photophysics_and_photochemistry_of_the_GFP_chromophore_ L2 - https://doi.org/10.1021/ja208496s DB - PRIME DP - Unbound Medicine ER -