Copper(I) halide complexes of 2,2,5,5-tetramethyl-imidazolidine-4-thione: Synthesis, structures, luminescence, thermal stability and interaction with DNA.

Five neutral mononuclear copper(I) halide complexes containing 2,2,5,5-tetramethylimidazolidine-4-thione (tmimdtH) and triphenylphosphane (PPh3) or tri-o-tolylphosphane (totp) have been prepared and structurally characterized by X-ray single-crystal analysis. The complexes containing PPh3 adopt the usual distorted tetrahedral geometry, while the presence of the bulkier totp forces the formation of three-coordinated trigonal planar species. The interaction of the compounds with calf-thymus DNA was monitored directly via UV-vis spectroscopy, DNA-viscosity measurements and indirectly via its competition with ethidium bromide for DNA studied by fluorescence emission spectroscopy. Intercalation was revealed as the most possible mode of binding. Furthermore, luminescent properties and thermal stabilities of the complexes were investigated.