Perfect isolation of π-conjugated molecules on inorganic surfaces with [1]rotaxane structure for enhancing electrical properties

Abstract π-Conjugated molecules have been utilized to functionalize inorganic surfaces to form organic–inorganic hybrid materials. However, the intrinsically strong π–π interaction results in undesirable aggregations on the inorganic surface, thereby disturbing the charge transfer through the organic–inorganic interface. In this study, a new strategy was developed using insulated π-conjugated molecules bearing a [1]rotaxane structure, where the π-conjugation was covered with covalently linked permethylated α-cyclodextrins. Aggregation-free immobilization was achieved on an inorganic surface by using insulated molecules to suppress intermolecular interaction. In the presence of these insulated molecules, the hybrid interface displayed excellent interfacial electrical properties. Moreover, the functionalized hybrid surface was utilized as an electrocatalyst to produce hydrogen peroxide using a Co(II)–chlorin complex, wherein the catalytic efficiency was improved dramatically by utilizing insulated molecules as bridging moieties at the interface. These results demonstrate that the insulation of π-conjugated molecules is a powerful strategy for modifying inorganic surfaces.