Navegando por Palavras-chave "excitation spectra"

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    Photophysical properties of coumarin compounds in neat and binary solvent mixtures: evaluation and correlation between solvatochromism and solvent polarity parameters
    (Sociedade Brasileira de Química, 2014-05-01) Moreira, Leonardo Marmo; Melo, Mirian M. de; Martins, Priscila A.; Lyon, Juliana Pereira; Romani, Ana Paula; Codognoto, Lucia [UNIFESP]; Santos, Sandra C. dos; Oliveira, Hueder Paulo Moisés de; Universidade Federal de São João Del Rei Departamento de Zootecnia; Universidade do Vale do Paraíba Instituto de Pesquisa e Desenvolvimento; Universidade Federal de São João Del Rei Departamento de Ciências Naturais; Universidade Federal do ABC Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de Pelotas Centro de Ciências Químicas, Farmacêuticas e de Alimentos; Universidade Federal do ABC Centro de Ciências Naturais e Humanas
    This work studied the fluorescent and solvatochromic properties of coumarin and its derivatives aiming to contribute in the elucidation of the excited state behavior of the molecule in solvent mixtures. This approach has been developed through a set of measurements involving different solvent ratios, which present distinct dielectric constants. The excitation and fluorescence maxima were largely blue-shifted with increasing participation of the organic solvent and the Stokes shifts were unusually low in mixtures with lower solvent polarity parameter, Δf. The emission intensity of coumarin was extremely sensitive to the polarity and the different structural conformations of solvents. These results influenced the spectroscopic behavior and explain the deviation from the linearity of the Lippert-Mataga relationship. The use of fluorescence spectroscopy makes the understanding of the behavior of the systems studied when in the presence of different environments being extremely important for the identification and characterization of coumarin in different pharmaceutical formulations.