SYNTHESIS AND CHARACTERIZATION OF LUMINESCENT MIXED-LIGAND ZINC(II) COMPLEXES CONTAINING A NOVEL DITHIOL LIGAND

A series of mixed ligand zinc(II) complexes containing the uncommon di thiol ligand dithiosquarate (dtsq) and having the formula Zn(dtsq)(N-N ), where N-N is 2,2'-biquinoline (biq), 1,10-phenanthroline (phen) and 1,4-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine or batho ), have been synthesized. The crystal structure of Zn(dtsq)(batho) has been determined by X-ray crystallography. This complex crystallizes i n the monoclinic space group P2(1)/n with a = 10.840(4), b = 17.630(7) , c = 15.826(6) Angstrom beta = 101.23(2)degrees, V = 2967(2) Angstrom (3) and Z = 4. The final refinement of all non-hydrogen atoms converge d at R = 0.052 and R(W) = 0.075 for the 3406 observed reflections. The crystal structure indicates a mononuclear complex with a distorted te trahedral geometry around the zinc atom and having one ethanol of solv ation hydrogen bonded to one of the oxygens on the dtsq ligand. The co mplexes Zn(dtsq)(phen) and Zn(dtsq)(batho) are emissive in the solid s tate at room temperature and both complexes exhibit multiple emissions at lower temperature. The two emissions observed are believed to be m etal assisted ligand to ligand charge transfer (LLCT) and an intraliga nd pi pi transitions.