Photoionization of N-alkylphenothiazines in titanosilicate mesoporous TiSBA-15 molecular sieves

Abstract

N-alkylphenothiazines (PCn, where n = 1, 6, 10, 16) have been incorporated into titanosilicate mesoporous TiSBA-15 molecular sieve and photoionized at room temperature to form stable alkylphenothiazine cation radicals (PCn-), which are monitored by electron spin resonance spectroscopy. The results show that the photoyield and stability of PCn+ radicals strongly depend on the titanium content in the TiSBA-15 framework, suggesting that framework Ti(IV) serves as an effective electron acceptor. The overall photoyield and stability of PCn+ increase with increasing titanium content of 2-4% in TiSBA-15 and with increasing alkyl chain length of the alkylphenothiazine. (C) 2001 Elsevier Science B.V. All rights reserved.