Photophysics of aminobenzazole dyes in silica-based hybrid materials |
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Authors: | Silvia Regina Grando Fabiano da Silveira Santos Márcia Russman Gallas Tania Maria Haas Costa Edilson Valmir Benvenutti Fabiano Severo Rodembusch |
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Affiliation: | 1. LSS??Laborat??rio de S??lidos e Superf??cies, Universidade Federal do Rio Grande do Sul, Avenida Bento Gon?alves, 9500, CP 15003, Porto Alegre-RS, CEP 91501-970, Brazil 2. LNMO??Laborat??rio de Novos Materiais Organicos, Universidade Federal do Rio Grande do Sul, Avenida Bento Gon?alves, 9500, CP 15003, Porto Alegre-RS, CEP 91501-970, Brazil 3. LAPMA??Laborat??rio de Altas Press?es e Materiais Avan?ados, Universidade Federal do Rio Grande do Sul, Avenida Bento Gon?alves, 9500, CP 15003, Porto Alegre-RS, CEP 91501-970, Brazil
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Abstract: | In this work two aminobenzazole derivatives (5-AHBT and 5-AHBI) were dispersed in silica-based hybrid materials with different surface hydrophobicity, which were obtained by the sol?Cgel process using tetraethylorthosilicate as inorganic precursor and dimethyldimethoxysilane as organic precursor, with a molar percent of organic precursor changing from 0 to 50%. The photophysics of the obtained doped silica hybrid materials was investigated by means ultraviolet?Cvisible diffuse reflectance and steady-state fluorescence emission spectroscopy in the solid state. The materials present absorption maxima located around 353 and 318?nm when doped with 5-AHBT and 5-AHBI, respectively. The red shifted absorption maxima of the 5-AHBT can be explained by the better electron delocalization allowed by the sulfur atom in relation to the nitrogen. The fluorescence emission spectra are located in the blue-green regions and the high Stokes shift indicates that the ESIPT mechanism occurs in the excited state for both dyes. The photophysical behavior of 5-AHBT shows that this dye is more affected by the matrix polarity due to specific interactions that take place in the ground state. |
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