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

Abstract

N-alkylphenothiazines (PC n , 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 (PC n +), which are monitored by electron spin resonance spectroscopy. The results show that the photoyield and stability of PC n + 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 PC n + increase with increasing titanium content of 2–4% in TiSBA-15 and with increasing alkyl chain length of the alkylphenothiazine.