Bis- and Tris(tetraazamacrocyclic) Copper Complexes with Disulfide Linkers

Abstract

Di- and trinuclear title complexes, 2Cu and 3Cu, containing, respectively, two and three macrocyclic fragments bound by aliphatic linkers with the -S–S- moieties have been synthesized by using cystamine dihydrochloride in the presence of triethylamine. The structure of the 2Cu complex in the solid state was confirmed by X-ray analysis. Two macrocyclic rings of 2Cu form a rectangular cavity of size 17.18 Å [S19···S19 (1 – x, –y, –z)] × 3.62 Å. The shorter dimension of the cavity is the shortest observed in bis(macrocycle)s studied by us. The bis(macrocyclic) molecules in the crystal lattice are surrounded by PF₆^– ions and water molecules. Redox properties of the new compounds were determined by applying various voltammetric techniques. The macrocyclic architectures remained stable in nonaqueous solutions. For the bis- and tris(macrocyclic) compounds, the exchange of one electron takes place almost independently at each of the copper centers. The complexes were self- assembled at the gold surface to produce stable monolayer-modified electrodes. The immobilization of these highly charged cations on the electrode required the application of appropriate negative potentials during the self-assembly process.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)