The origin of the photochromic properties of diarylethenes is a conical intersection (which we have located computationally), but we show that dynamics calculations are necessary to explain why the conical intersection is accessible, because the excited-state reaction path is not contained in the branching space defining the intersection. Four different systems have been studied: 1,2-di(3-furyl)ethene, 1,2-di(3-thienyl)ethene, 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene, and a model hydrocarbon system. Critical points on the ground- and excited-state potential energy surfaces were calculated using complete active space self-consistent field (CASSCF) theory; dynamics calculations were carried out using the molecular mechanics-valence bond (MMVB) method. The main experimental observations (i.e., picosecond time domain, quantum yield, temperature dependence, and fluorescence) can be interpreted on the basis of our results.
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Data di pubblicazione: | 2003 | |
Titolo: | Can Diarylethene Photochromism Be Explained by a Reaction Path Alone? A CASSCF Study with Model MMVB Dynamics | |
Autori: | M. Boggio-Pasqua; M. Ravaglia; M.J. Bearpark; M. Garavelli; M.A.Robb | |
Rivista: | JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY | |
Abstract: | The origin of the photochromic properties of diarylethenes is a conical intersection (which we have located computationally), but we show that dynamics calculations are necessary to explain why the conical intersection is accessible, because the excited-state reaction path is not contained in the branching space defining the intersection. Four different systems have been studied: 1,2-di(3-furyl)ethene, 1,2-di(3-thienyl)ethene, 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene, and a model hydrocarbon system. Critical points on the ground- and excited-state potential energy surfaces were calculated using complete active space self-consistent field (CASSCF) theory; dynamics calculations were carried out using the molecular mechanics-valence bond (MMVB) method. The main experimental observations (i.e., picosecond time domain, quantum yield, temperature dependence, and fluorescence) can be interpreted on the basis of our results. | |
Digital Object Identifier (DOI): | 10.1021/jp036862e | |
Handle: | http://hdl.handle.net/11392/521251 | |
Appare nelle tipologie: | 03.1 Articolo su rivista |