Click reactions (e.g., Huisgen cycloaddition) on metal oxide nanostructures offer a versatile and robust surface molecular modification for various applications because they form strong covalent bonds in a wide range of molecular substrates. This study reports a rational strategy to maximize the conversion rate of surface click reactions on single-crystalline ZnO nanowires by monitoring the reaction progress. p-Polarized multiple-angle incidence resolution spectrometry (pMAIRS) and Fourier-transformed infrared (FT-IR) spectroscopy were employed to monitor the reaction progress of an azide-terminated self-assembled monolayer (SAM) on single-crystalline ZnO nanowires. Although various reaction parameters including the concentration of Cu(I) catalysts, triazolyl ligands, solvents, and target alkynes were systematically examined for the surface click reactions, 10−30% of terminal azide on the nanowire surface remained unreacted. Temperature-dependent FT-IR measurements revealed that such unreacted residual azides deteriorate the thermal stability of the nanowire molecular layer. To overcome this observed conversion limitation of click reactions on nanostructure surfaces, we considered the steric hindrance around the closely packed SAM reaction points, then experimented with dispersing the azide moiety into a methyl-terminated SAM. The mixed-SAM method significantly improved the azide conversion rate to almost 100%. This reaction method enables the construction of spatially patterned molecular surface modifications on metal oxide nanowire arrays without detrimental unreacted azide groups.

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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.