A QM/MM study of the conformation stability and electronic structure of the photochromic switches derivatives of DHA/VHF in acetonitrile solution

Autor(es)

Cardenuto, Marcelo Hidalgo ^[1] ; Cezar, Henrique M. ^[1] ; Mikkelsen, V, Kurt ; Sauer, Stephan P. A. ^[2] ; Coutinho, Kaline ^[1] ; Canuto, Sylvio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis, Rua Matao 1371, Cidade Univ, BR-05508090 Sao Paulo - Brazil

^[2] Mikkelsen, Kurt, V, Univ Copenhagen, Dept Chem, Univ Pk 5, DK-2100 Copenhagen - Denmark

• Tipo de documento: Artigo Científico
• Fonte: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 251, APR 15 2021.
• Citações Web of Science: 0

Resumo

We present a detailed theoretical study of the electronic absorption spectra and thermochemistry of molecular photoswitches composed of one and two photochromic units of dihydroazulene (DHA)/vinyl-heptafulvene (VHF) molecules. Six different isomers are considered depending on the ring opening/closure forms of the DHA units. The solvent effect of acetonitrile is investigated using a sequential Molecular Mechanics/Quantum Mechanics approach. The thermochemical investigations of these photochromic molecules were performed using the Free Energy Perturbation method, and the simulations were performed using Configurational Bias Monte Carlo. We show that to open the 5-member ring of the DHA, there is no significant gain in thermal release of energy for the back reaction when a unit or two DHA units are considered. Overall, we found agreement between the solvation free energy based on Monte Carlo simulations and the continuum solvent model. However, the cavitation term in the continuum model is shown to be a source of disagreement when the non-electrostatic terms are compared. The electronic absorption spectra are calculated using TDDFT CAM-B3LYP/cc-pVDZ. Agreement with experiment is obtained within 0.1 eV, considering statistically uncorrelated configurations from the simulations. Inhomogeneous broadening is also considered and found to be well described in all cases. (C) 2021 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 14/50983-3 - INCT 2014: fluidos complexos
• Beneficiário: Antonio Martins Figueiredo Neto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/25249-7 - Efeitos de solvente e teoria de resposta em ótica não-linear de segunda ordem
• Beneficiário: Marcelo Hidalgo Cardenuto
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado