Syntheses, crystal structures and fluorescent properties of imidazole based mixed-ligand nickle and cadmium complexes

Four novel mixed-ligand nickle and cadmium complexes [Cd(tolu)(2)(imi)(3)] (1) [CdCl2(imi)(2)]n (2), [Ni(imi)(6)] (tolu)(2) (3) and [Ni(mand)(2)(imi)(2)].H2O (4) (imi = imidazole, Htolu = o-toluic acid, Hmand = mandelic acid) were synthesized and isolated in solid state based on nickle and cadmium salts, imidazole and different car-boxylic acids. These complexes were characterized by FT-IR, elemental analyses, thermogravimetric (TG) ana-lyses, UV-vis, X-ray structural analyses and fluorescence spectra. Complexes 1 and 4 are neutral mixed-ligand molecules. Complex 2 exhibits a 2D chain constructed by [CdCl2(imi)(2)] units. Complex 3 possesses [Ni(imi)(6)](2-)anions with uncoordinated tolulate anions. In complexes 1-4, each imidazole ligand provides one nitrogen atom for coordination. Tolulate and mandelate ligands coordinate to the metal through carboxyl oxygen or hydroxyl oxygen atoms. Plenty of intramolecular hydrogen bonds as N-H...O and O-H...O interactions are observed in these complexes. Fluorescence properties of the complexes have been deeply investigated and the result reveals that Fe3+ ion has the greatest effect on fluorescence intensity of complex 3. The fluorescence intensity decreases with the increase of iron concentration.