Density Functional Theory Applied to Excited State Intramolecular Proton Transfer in Imidazole-, Oxazole-, and Thiazole-Based Systems

Autor(es)

de Carvalho, Fabricio ^[1] ; Coutinho Neto, Mauricio D. ^[1] ; Bartoloni, Fernando H. ^[1] ; Homem-de-Mello, Paula ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-5001 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Molecules; v. 23, n. 5 MAY 2018.
• Citações Web of Science: 1

Resumo

Excited state intramolecular proton transfer (ESIPT) is a photoinduced process strongly associated to hydrogen bonding within a molecular framework. In this manuscript, we computed potential energy data using Time Dependent Density Functional Theory (TDDFT) for triphenyl-substituted heterocycles, which evidenced an energetically favorable proton transfer on the excited state (i.e., ESIPT) but not on the ground state. Moreover, we describe how changes on heterocyclic functionalities, based on imidazole, oxazole, and thiazole systems, affect the ESIPT process that converts an enolic species to a ketonic one through photon-induced proton transfer. Structural and photophysical data were obtained theoretically by means of density functional theory (DFT) calculations and contrasted for the three heterocyclics. Different functionals were used, but B3LYP was the one that adequately predicted absorption data. It was observed that the intramolecular hydrogen bond is strengthened in the excited state, supporting the occurrence of ESIPT. Finally, it was observed that, with the formation of the excited state, there is a decrease in electronic density at the oxygen atom that acts as proton donor, while there is a substantial increase in the corresponding density at the nitrogen atom that serves as proton acceptor, thus, indicating that proton transfer is indeed favored after photon absorption. (AU)

• Processo FAPESP: 17/23416-9 - Fotossensibilizadores: estudos de propriedades fundamentais e aplicações biológicas
• Beneficiário: Paula Homem-de-Mello
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/13807-7 - Novas ferramentas para o estudo de reações de transferência de elétron em sistemas modelo do PS II
• Beneficiário: Fernando Heering Bartoloni
• Modalidade de apoio: Auxílio à Pesquisa - Regular