A series of single, double, and triple Me2biim-bridged dinuclear, trinuclear, and polymeric complexes:: Syntheses, crystal structures, and luminescent properties

Reaction of ZnCl2 and Me(2)biim (Me(2)biim = N,N'-dimethyl-2,2-'-biimidazole) in acidic or neutral aqueous solutions gave the noncoordinated ZnCl(4)(.)H(2)Me(2)biim (1) or the double Me(2)biim bridged [Zn2Cl4(mu-Me(2)biiM)(2)] (2). Use of CdX2 (X = Cl, Br, I) instead of ZnCl2 yielded the single Me(2)biim bridged one-dimensional coordination polymer [CdX2(mu-Me(2)biim)], (X = Cl, 3; Br, 4; 1, 5). The stacking of the infinite chains are dominated by C-H... X interactions in 3 and 4 but by vertical bar(...)vertical bar interactions in 5, responsible for their different crystal structures. Use of Zn(NO3)(2) instead of ZnCl2 produced the novel triple Me(2)biim-bridged [Zn-2(mu-Me(2)biim)(3)(H2O)(2)](NO3)(4)(H2O)-H-. (6). The unprecedented hexa-Me(2)bim bridged trinuclear [Cd-3(mu-Me(2)biiM)(8)](2)(ClO4)](2)(H2O)(6) (7) was obtained by using Cd(CH3CO2)(2) in the presence of NaClO4. Compounds 1-7 were characterized by X-ray crystallography and IR. Examination of photophysical properties of 1-7 indicates that the fluorescence emission of Me(2)biim has been effectively enhanced, quenched, or shifted in its metal complexes 1-7.