Full-Dimensional Excited-State Intramolecular Proton Transfer Dynamics of Salicylic Acid

Abstract

Salicylic acid (SAc) and its excited-state intramolecular proton transfer (ESIPT) capabilities have been studied both experimentally and theoretically by static calculations. However, to our knowledge, no radiationless pathway has been proposed so far. Instead, excited-state deactivation was only investigated via fluorescence. Therefore, we will present full-dimensional photodynamics of SAc using the floating-occupation configuration-interaction (FOCI) treatment with single and paired double excitations based on the semiempirical RM1 Hamiltonian. To further clarify mechanistic details, the potential energy surface (PES) is scanned along the proton transfer coordinates in one and two dimensions. The time-evolution of relevant degrees of freedom (DOF), quantum yields and isomer populations are evaluated from 200 surface-hopping trajectories. It was found that a deactivation pathway from the excited state to the ground state is indeed accessible through a conical intersection, via rotation of the carboxyl group. Together with the ESIPT process, this rotation can also interchange the protons of the two (formal) OH groups, which makes the overall dynamics still more complex. Our full-dimensional photodynamics study provides a comprehensive overview of all these entangled steps.

Excitation-Dependent Multiple Fluorescence of a Substituted 2-(2′-Hydroxyphenyl)benzoxazole

“…The energies of HBO and compound 1 along the OH coordinates on the ground and excited states were calculated on the DFT/def2-SV­(P) and TDDFT/def2-SV­(P) levels of theory, respectively. The minimal energy path calculation required to freeze one internal coordinate, in this case the distance of the OH bond, while all other internal coordinates were allowed to relax. ,− The stationary points (minima and transition states as marked on Figure ) along the OH coordinates were preliminarily identified. These stationary points were then optimized again without any frozen coordinate using the bigger basis sets def2-TZVP to produce the data listed in Table .…”

Charge transfer dynamics at the boron subphthalocyanine chloride/C60 interface: non-adiabatic dynamics study with Libra-X

“…89 NDDO-based methods, such as AM1 and RM1, have been used previously in a number of NA-MD studies. [95][96][97][98] In this work we selected RM1 method in favour of MNDO for the sake of convenience of the dispersion energy adjustment. The MNDO may be another suitable methodology to simulate charge transfer if the dispersion energy is adjusted well to reproduce the SubPc/C 60 binding energies of DFT.…”

Photooxidation of water with heptazine-based molecular photocatalysts: Insights from spectroscopy and computational chemistry

“…6, exhibits a topography which is characteristic for H-atom transfer reactions. [44][45][46][47][48][49] The well on the left hand side, corresponding to the locally excited 1 Experimentally, the water photooxidation reaction was explored using suspensions of TAHz in water. 21 The extinction and stationary photoluminescence spectra of TAHz in water are shown in Fig.…”