A new interpretation of the absorption and the dual fluorescence of Prodan in solution

Autor(es)

Vequi-Suplicy, Cintia C. ^{[1, 2]} ; Orozco-Gonzalez, Yoelvis ^{[1, 3]} ; Lamy, M. Teresa ^[1] ; Canuto, Sylvio ^[1] ; Coutinho, Kaline ^[1]

Afiliação do(s) autor(es)

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

^[2] Fdn IMDEA Nanociencia Cantoblanco, Madrid 28049 - Spain

^[3] Georgia State Univ, Dept Chem, Atlanta, GA 30302 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Chemical Physics; v. 153, n. 24 DEC 28 2020.
• Citações Web of Science: 0

Resumo

Remarkable interest is associated with the interpretation of the Prodan fluorescent spectrum. A sequential hybrid Quantum Mechanics/Molecular Mechanics method was used to establish that the fluorescent emission occurs from two different excited states, resulting in a broad asymmetric emission spectrum. The absorption spectra in several solvents were measured and calculated using different theoretical models presenting excellent agreement. All theoretical models {[}semiempirical, time dependent density functional theory and and second-order multiconfigurational perturbation theory] agree that the first observed band at the absorption spectrum in solution is composed of three electronic excitations very close in energy. Then, the electronic excitation around 340 nm-360 nm may populate the first three excited states (pi-pi L-{*}(b), n-pi ({*}), and pi-pi L-{*}(a)). The ground state S-0 and the first three excited states were analyzed using multi-configurational calculations. The corresponding equilibrium geometries are all planar in vacuum. Considering the solvent effects in the electronic structure of the solute and in the solvent relaxation around the solute, it was identified that these three excited states can change the relative order depending on the solvent polarity, and following the minimum path energy, internal conversions may occur. A consistent explanation of the experimental data is obtained with the conclusive interpretation that the two bands observed in the fluorescent spectrum of Prodan, in several solvents, are due to the emission from two independent states. Our results indicate that these are the n-pi ({*}) S-2 state with a small dipole moment at a lower emission energy and the pi-pi L-{*}(b) S-1 state with large dipole moment at a higher emission energy. (AU)

• Processo FAPESP: 06/55513-9 - Estudos experimentais e teóricos dos espectros eletrônicos das sondas fluorescentes Prodan e Laurdan em solventes e bicamadas lipídicas
• Beneficiário: Cíntia Cristina De Vequi Suplicy
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 12/15161-7 - Efeito do solvente na dinâmica de estados eletrônicos excitados e nos mecanismos de decaimento não radiativo
• Beneficiário: Yoelvis Orozco González
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 14/50983-3 - INCT 2014: fluidos complexos
• Beneficiário: Antonio Martins Figueiredo Neto
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 10/08365-0 - Estudo Teórico de Nucleosídeos Lipofílicos em Solventes e em Monocamadas Lipídicas Utilizando Métodos Híbridos de Mecânica Quântica e Mecânica Molecular.
• Beneficiário: Cíntia Cristina De Vequi Suplicy
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 17/11631-2 - CINE: desenvolvimento computacional de materiais utilizando simulações atomísticas, meso-escala, multi-física e inteligência artificial para aplicações energéticas
• Beneficiário: Juarez Lopes Ferreira da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia