Modified mesoporous MCM-41 as hosts for photochromic spirobenzopyrans

Autor: Hermenegildo García, Isabel Casades, Manoj Narayana Pillai, Mercedes Alvaro
Rok vydání: 2002
Předmět:
Zdroj: Photochemical & Photobiological Sciences. 1:219-223
ISSN: 1474-9092
1474-905X
DOI: 10.1039/b110936g
Popis: The influence of the chemical composition and silylation of mesoporous MCM-41 materials on the photochromic behaviour of adsorbed spiropyran (BIPS) and 6-nitrospiropyran was studied. Upon incorporation, the spiropyrans underwent ring opening to form either zwitterionic merocyanine or its corresponding O-protonated form. In all silica MCM-41 or in the MCM-41 containing aluminium, the O-protonated merocyanine was predominantly formed. In the case of MCM-41 modified by silylation of the OH groups, a mixture of zwitterionic merocyanine and spiropyran was present. The photochromic response was studied by means of steady-state irradiation and by laser flash photolysis. Steady-state irradiation (lambda450 nm) of the solid samples gives rise in all cases to an intensity decrease of the absorption bands corresponding to either the protonated or the unprotonated merocyanine form (reverse photochromism). In contrast, laser flash photolysis at 308 nm of spiropyrans supported on silylated MCM-41 allows observation of the photochemical ring opening of residual spiropyran to the corresponding zwitterionic form (normal photochromism).
Databáze: OpenAIRE
Externí odkaz: