Functionalization and solubilization of small carbon nanoparticles with facile additions of malonic esters

Abstract Reactions of dibutyl malonate (DBM) and dioctyl malonate (DOM) with small carbon nanoparticles (CNPs) could be facilitated facilely and efficiently by relatively brief microwave irradiation for products of high solubility in nonpolar organic solvents, obviously different from the starting CNPs. The reaction products were characterized systematically by using high-resolution electron microscopy imaging, quantitative proton and carbon NMR analyses, optical absorption and fluorescence spectroscopy evaluations, and other instrumental measurements, with the results suggesting DBM-CNP and DOM-CNP adducts, in which each CNP is surface functionalized with a large number of DBM and DOM units, respectively. Such adducts should be comparable, at least phenomenologically, with methanofullerene multi-adducts from Bingel-Hirsch reactions of fullerene with derivatized malonate, even though mechanistically the DBM and DOM additions to CNPs are more likely due to DBM and DOM respective radicals generated in the microwave irradiation. The significance and potentially valuable applications of the ability for CNPs to engage in such facile and highly efficient radical addition reactions are discussed.