Azide-Engineered Nanocrystals Enable Direct Grafting of Conjugated Polymers via Click Chemistry

Organic-inorganic hybrid nanocomposites comprising conjugated polymers in close contact with inorganic nanocrystals (NCs) were crafted via a catalyst-free click reaction. It highlights simple, robust, yet effective sodium azide treatment to effectively detach all of the insulating aliphatic ligands, including covalently bonded ones, from NC surfaces as well as to introduce covalently bonded azide functional sites, yielding azide-terminated NCs for click coupling. Subsequently, ethynyl-terminated organics (e.g., 1-octyne and ethynyl-terminated poly-(3-hexylthiophene) (-P3HT)) were tethered with azide-functionalized NCs via catalyst-free azide-alkyne cycloaddition, yielding semiconducting organic-inorganic nanocomposites (e.g., 1-octyne-CdSe/ZnS quantum dots and P3HT-CdSe tetrapod nanocomposites). The success of the click reaction was substantiated by Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopies. A significant reduction in the ethynyl proton signal after the click reaction and decreased azide absorption in FTIR spectra strongly support the anchoring of ethynyl-terminated organics (e.g., 1-octyne and -P3HT) with azide-functionalized NCs. This strategy for the preparation of functional organic-tethered nanocrystals enables the direct introduction of reactive azide sites onto bare NCs, eliminating the need for redundant organic bifunctional ligands or tedious multistep procedures, and may offer a promising route to functional nanocomposites for optoelectronic applications.