Chang, Xue-Ping; Zhang, Teng-Shuo; Fang, Ye-Guang; Cui, Ganglong published an article in 2021. The article was titled 《Quantum mechanics/molecular mechanics studies on the photophysical mechanism of methyl salicylate》, and you may find the article in Journal of Physical Chemistry A.Reference of Methyl Salicylate The information in the text is summarized as follows:
Me salicylate (MS) as a subunit of larger salicylates found in com. sunscreens has been shown to exhibit keto-enol tautomerization and dual fluorescence emission via excited-state intramol. proton transfer (ESIPT) after the absorption of UV radiation. However, its excited-state relaxation mechanism is unclear. Herein, we have employed the quantum mechanics(CASPT2//CASSCF)/mol. mechanics method to explore the ESIPT and excited-state relaxation mechanism of MS in the lowest three electronic states, i.e., S0, S1, and T1 states, in a methanol solution Based on the optimized geometric and electronic structures, conical intersections and crossing points, and min.-energy paths combined with the computed linearly interpolated Cartesian coordinate paths, the photophys. mechanism of MS has been proposed. The S1 state is a spectroscopically bright 1ππ* state in the Franck-Condon region. From the initially populated S1 state, there exist three nonradiative relaxation paths to repopulate the S0 state. In the first one, the S1 system (i.e., ketoB form) first undergoes an ESIPT path to generate an S1 tautomer (i.e., enol form) that exhibits a large Stokes shift in experiments The generated S1 enol tautomer further evolves toward the nearby S1/S0 conical intersection and then hops to the S0 state, followed by the backward ground-state intramol. proton transfer (GSIPT) to the initial ketoB form S0 state. In the second one, the S1 system first hops through the S1 → T1 intersystem crossing (ISC) to the T1 state, which then further decays to the S0 state via T1 → S0 ISC at the T1/S0 crossing point. In the third path, the T1 system that stems from the S1 → T1 ISC process via the S1/T1 crossing point first takes place a T1 ESIPT to generate a T1 enol tautomer, which can further decay to the S0 state via T1-to-S0 ISC. Finally, the GSIPT occurs to back the system to the initial ketoB form S0 state. Our present work could contribute to understanding the photophysics of MS and its derivatives In the experiment, the researchers used many compounds, for example, Methyl Salicylate(cas: 119-36-8Reference of Methyl Salicylate)
Methyl Salicylate(cas: 119-36-8) is a natural herbivore-induced plant volatile. It is a naturally occurring product in trees, legumes, exotic plants, vegetables, berries, and the primary constituent of the oil of wintergreen.Methyl Salicylate is produced from salicylic acid.Reference of Methyl Salicylate
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