Nanospheres of copper(III) 1,2-dicarbomethoxy-1,2-dithiolate and its composite with water soluble carbon nanotubes

Abstract

We report here the synthesis and structural characterization of a new discrete bis-dithiolene complex, [PPh₄][Cu(DMED)₂] (1; DMED = 1,2-dicarbomethoxy-1,2-dithiolate), involving the reaction between a copper polysulfide precursor with activated acetylene. 1 is stable, showing a sulfur-based radical character, as observed by electronic, EPR and cyclic voltammetric studies. This complex, possessing terminal –COOCH₃ groups, forms nanospheres by hydrogen bonding in a mixture of solvents containing water as one of the components. These nanospheres further aggregate with water soluble (carboxylated) carbon nanotubes (wsCNTs). These nano-composites are assisted by hydrogen bonding between the carboxylic acid groups of the wsCNTs and the peripheral –COOCH₃ groups of the coordinated dithiolenes of the nanospheres, which is promoted by water molecules. Interaction between the nanospheres on wrapping with wsCNTs, in forming the nano-composites, showed a perturbed EPR signal of the sulfur radical originating from the oxidised dithiolate ligand of the discrete complex 1.