SYNTHESES AND PROPERTIES OF THE COMPLEXES OF COPPER(II) WITH 1,4,7,10-TETRAAZACYCLOTRIDECANE-11,13-DIONE APPENDED WITH 2-METHYLTHIOPHENE PENDANTS

Two new macrocyclic 1,4,7,10-tetraazacyclotridecane-11,13-diones (diox o[13]aneN(4)) bearing 2-methylthiophene as additional pendants, H2L1 a nd H2L2, have been synthesized and characterized. The solution behavio ur of the copper(II) complexes has been studied by UV-Vis, ESR and cyc lic voltammetric techniques. A remarkable red-shift was observed for t he absorption band maxima of the electronic spectra of CuL1 and CuL2 c ompared to that of the corresponding unsubstituted macrocycle copper c omplex CuL (H2L = macrocyclic ligand, 1,4,7,10-tetraazacyclotridecane- 11,13-dione, without pendant groups). The ESR spectra have been studie d at 298 K and 112 K, and reflect weaker in-plane bonding in CuL1 and CuL2 compared to CuL. The E-1/2 of the copper complexes increases with the increase of the number of additional pendants, and the reasons fo r this are discussed.