Abstract
Titanosilicate microporous molecular sieves, activated by UV irradiation in the presence of H2O and molecular oxygen at room temperature, decompose a molecule having a size equivalent to the pore diameter of the catalyst, but are almost inactive for decomposition of a molecule having larger or smaller size. ESR analysis indicated that this size-selective photocatalytic activity is brought about by a combination of shortened lifetime of charge-transfer excited state of tetrahedrally coordinated titanium oxide (TiO4) species in the presence of H2O and restricted diffusion of the guest molecule inside the micropore of the catalyst. This observation indicates a potential utility of the titanosilicate molecular sieve as a photocatalyst for selective transformation of organic functional groups, associated with the size reduction of the molecule, so called "molecular shave" type reactions.
