Study on the fluorescence properties of benzopyrylium salt in Ti-HMS

Benzopyrylium. salt S-2 (2,4-diphenyl-5,6,7,8-tetrahedro-1-benzopyrylium perchlorate) was introduced into the channels of mesoporous molecular sieves Ti-HMS with different Ti content by impregnation method. The fluorescence properties (excitation, emission and lifetime) of S-2 in these sieves have been studied. The results indicated that S-2 molecules interact with the isolated framework Ti(4+) on the internal surface of Ti-HMS and the amount of S-2 introduced increases with the increasing of isolated titanium content. The observed biexponential decay can be interpreted in terms of two absorbed site, the isolate Ti site and the silanol site. The S-2 molecules absorbed on the Ti site have longer lifetime. (C) 2004 Elsevier Ltd. All rights reserved.