Photophysics of aminobenzazole dyes in silica-based hybrid materials

• Published in: Journal of sol-gel science and technology Vol. 63; no. 2; pp. 235 - 241
• Main Authors: Grando, Silvia Regina, da Silveira Santos, Fabiano, Gallas, Márcia Russman, Costa, Tania Maria Haas, Benvenutti, Edilson Valmir, Rodembusch, Fabiano Severo
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Boston Springer US 01.08.2012; Springer; Springer Nature B.V
• Subjects: Absorption; Ceramics; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Derivatives; Dyes; Emission analysis; Emission spectra; Exact sciences and technology; Fluorescence; General and physical chemistry; Glass; Ground state; Hydrophobicity; Inorganic Chemistry; Materials Science; Maxima; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Polarity; Precursors; Reflectance; Silicon dioxide; Sol-gel processes; Spectrum analysis; Sulfur; Ultraviolet reflection; Fluorescence; Hybrid xerogel materials; ESIPT; Photoactive matrix; Binary compound; Stokes shift; Organic dye; Hybrid material; Hydrophobicity; Nitrogen; Precursor; Steady state; Silica; Mechanism; Solid state; Absorption; Sol gel process; Polarity; Sulfur; Xerogel; Reflectance
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-012-2720-z

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–gel 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–visible 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.