Solvation Structures and Deactivation Pathways of Luminescent Isothiazole-Derived Nucleobases: (tz)A, (tz)G, and I-tz

Autor(es)

de Araujo, Adalberto Vasconcelos Sanches ^[1] ; Valverde, Danillo ^[2] ; Canuto, Sylvio ^[2] ; Borin, Antonio Carlos ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Fundamental Chem, Inst Chem, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Inst Phys, BR-05508090 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 124, n. 34, p. 6834-6844, AUG 27 2020.
• Citações Web of Science: 0

Resumo

The photophysical relaxation pathways of (tz)A, (tz)G, and I-tz luminescent nucleobases were investigated with the MS-CASPT2 quantum-chemical method and double-zeta basis sets (cc-pVDZ) in gas and condensed phases (1,4-dioxane and water) with the sequential Monte Carlo/CASPT2 and free energy gradient (FEG) methods. Solvation shell structures, in the ground and excited states, were examined with the pairwise radial distribution function (G(r)) and solute-solvent hydrogen-bond networks. Site-specific hydrogen bonding analysis evidenced relevant changes between both electronic states. The three luminescent nucleobases share a common photophysical pattern, summarized as the lowest-lying 1(pi pi{*}) bright state that is populated directly after the absorption of radiation and evolves barrierless to the minimum energy structure, from where the excess of energy is released by fluorescence. From the (1)(pi pi{*})(min) region, the conical intersection with the ground state ((pi pi{*}/GS)(CI)) is not accessible due to the presence of high energetic barriers. By combining the present results with those reported earlier by us for the pyrimidine fluorescent nucleobases, we present a comprehensive description of the photophysical properties of this important class of new fluorescent nucleosides. (AU)

• Processo FAPESP: 17/02612-4 - Dinâmica de estados excitados e propriedades espectroscópicas de derivados de RNA e DNA naturais e sintéticos em meio solvente
• Beneficiário: Danillo Pires Valverde
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 14/50983-3 - INCT 2014: fluidos complexos
• Beneficiário: Antonio Martins Figueiredo Neto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 18/19454-5 - Estrutura e Fotofísica de Bases Nucleicas Fluorescentes e Pares de Bases Mediados por Metais de Transição
• Beneficiário: Antonio Carlos Borin
• Modalidade de apoio: Auxílio à Pesquisa - Regular