Copper coordination compounds with (5Z,5Z′)-2,2′-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4H-imidazol-4-ones. Comparison with sulfur analogue

A series of new organic ligands (5Z,5Z′)-2,2′-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4H-imidazol-4-ones (L) consisting of two 5-(2-pyridylmethylene)-3,5-dihydro-4H-imidazol-4-one units linked with polymethylene chains of various lengths (n = 2–10, where n is the number of CH(2) units) have been synthesized. The reactions of these ligands with CuCl(2)·2H(2)O and CuClO(4)·6H(2)O gave Cu(2+) or Cu(1+) containing mono- and binuclear complexes with Cu(2)LCl(x) (x = 2–4) or CuL(ClO(4))(y) (y = 1, 2) composition. It was shown that the agents reducing Cu(2+) to Cu(1+) in the course of complex formation can be both a ligand and an organic solvent in which the reaction is carried out. This fundamentally distinguishes the selenium-containing ligands L from their previously described sulfur analogs, which by themselves are not capable of reducing Cu(2+) during complexation under the same conditions. A higher cytotoxicity and reasonable selectivity to cancer cell lines for synthesized complexes of selenium-containing ligands was shown; unlike sulfur analogs, ligands L themselves demonstrate a high cytotoxicity, comparable in some cases to the toxicity of copper-containing complexes.