Enhanced Catalytic Activity on Titanosilicate Molecular Sieves Controlled by Cation−π Interactions

A new class of heterogeneous catalytic systems utilizing cation-guest interactions was designed based on microporous titanosilicate molecular sieves. Introducing heavier alkali metal cations on ion-exchange sites of the framework resulted in a significant enhancement of the catalytic activity for oxidation of cyclohexene and styrene, whereas such an enhancement was not observed in oxidation of cyclohexane without π systems. Distinct relationships between the catalytic activities and intermolecular interaction energies which were determined by IR spectroscopic and computational approaches clearly evidenced the predominance of the cation-π interaction in this catalytic system.