Synthesis and optical properties of 2,6-anthracene-bridged periodic mesostructured organosilicas

2,6-Bis(triethoxysilyl)anthracene was first synthesized by rhodium-catalyzed disilylation of 2,6-bis(trifluoromethanesulfonyloxy)anthracene with triethoxysilane. Using the new precursor, anthracene-bridged periodic mesostructured organosilicas were obtained without cleavage of the Si-C bondings. The anthracene-silica hybrids showed absorption at near ultraviolet region and blue-green fluorescence with a quantum yield of 0.13-0.15. The absorption and fluorescence behaviors of the 2.6-anthracene-silica hybrid film were compared with those of the previously reported 9,10-anthracene-silica hybrid film. Their absorbances Suggest that the 2,6-anthracene groups were packed more densely than the 9,10-anthracene groups in the mesoporous frameworks due to smaller steric hindrance. In spite of the densely packed structure, the 2.6-anthracene-silica hybrid film showed fluorescence emission at shorter wavelengths and a higher quantum yield than those of the 9,10-anthracene-silica hybrid film, suggesting relatively weak interaction between the anthracene groups in the framework because of restriction of intramolecular rotation motion for Substitution at 2,6-positions of anthracene. Dilution of the anthracene groups in the framework with trimethoxysilane promoted monomeric fluorescence and an increase of its quantum yield up to 0.18. (c) 2008 Elsevier Inc. All rights reserved.