[3 + 2] cycloaddition reaction of azomethine ylides generated by thermal ring opening of aziridines onto carbon nanohorns

Abstract

The covalent functionalization of carbon nanohorns (CNHs) via the 1,3-dipolar cycloaddition reaction of azomethine ylides generated by the thermal ring opening of aziridines bearing electron-withdrawing substituents is described. This is a complementary methodology, to the in situ generated azomethine ylides derived upon the thermal decarboxylation of immonium salts originated from condensation of α-aminoacids with aldehydes, for the surface modification of CNHs. The modified CNHs featuring pyrrolidine rings fused to the junction between two six-membered rings of CNHs 4a and 4b were characterized by Raman and ATR-IR spectroscopy as well as DLS, while imaged by HR-TEM microscopy and the loading of the organic addends was calculated by thermogravimetry. Furthermore, gold nanoparticles were grown and immobilized on CNH-based material 4b, yielding pyrrolidino-modified CNH/Au_nano hybrid material 5, which was additionally imaged by STEM-ADF to identify the presence of gold nanoparticles as verified by EDX spectroscopy analysis.