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Springer Verlag, Journal of Sol-Gel Science and Technology, 1(65), p. 83-92

DOI: 10.1007/s10971-012-2770-2

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Luminescent urea cross-linked tripodal siloxane-based hybrids

This paper is available in a repository.
This paper is available in a repository.

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Abstract

This work reports the synthesis of novel sol–gel derived urea cross-linked tripodal siloxane-based hybrids (classed as tri-ureasils) modified by the addition of phenyl-triethoxysilane (PTES) and diphenyldimethoxysilane (DPDMS). The materials were produced as transparent monoliths and thin films (thickness = 3.3–17.5 ± 0.1 lm) and characterized by X-ray diffraction, mid-infrared spec-troscopy, 29 Si and 13 C nuclear magnetic resonance, ther-mogravimetric analysis, ultraviolet/visible (UV/Vis) absorption and photoluminescence spectroscopies. The role played by PTES and DPDMS as light harvesting chro-mophores has been discussed and quantified through emis-sion quantum yield and UV/Vis absorption measurements. All the hybrids show efficient emission at room temperature in the blue spectral region with maximum emission quantum yield values ranging from 0.01 ± 0.001 to 0.10 ± 0.01. The highest values were found for the tri-ureasils incorporating PTES and DPDMS essentially due to an increase in the absorption coefficient (from 1.4 9 10 3 cm -1 , for the pris-tine tri-ureasil, to 8.6 9 10 3 cm -1 , for the hybrids modified by the chromophores). The existence of energy transfer between the DPDMS and PTES excited states and the hybrid host intrinsic emitting levels (NH/C=O-and sili-ceous-related levels) has been discussed.