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.

Cation‐π interaction is an intermolecular interaction between the face of a π system and an adjacent cation, which brings about a change in molecular dynamics of organic reactants in catalysis. In this study, a series of alkali metal cations‐anchored TiO2/SiO2 hybrid catalysts were prepared based on organo‐functionalized MCM‐41 mesoporous silica, in order to examine the effect of cation‐π interaction in heterogeneous catalysis. Immobilizing heavier alkali metal cations on surface‐functionalized carboxylic acid ion‐exchange sites provided a dramatic impact on diffusion properties of aromatic molecules, which led to a significant enhancement in photocatalytic degradation of phenol in water under ultraviolet light irradiation, whereas such an enhancement was not observed in degradation of cyclohexanol without π electrons. A distinct relationship was observed between the catalytic activities and adsorption energies determined by thermogravimetric analysis, which evidenced a role of the cation‐π interaction as a diffusion‐controlling tool in this reaction system.