Syntheses, structures and fluorescence properties of two Zn(II) coordination compounds with cis-4-cyclohexene-1,2-dicarboxylate ligand

Two Zn(II) coordination compounds, [Zn2(L)2(bipy)]n (1) and [Zn2(L)2(phen)2]2·14.75H2O (2), (H2L = cis-4-cyclohexene-1,2-dicarboxylic acid; bipy = 4,4’-bipyridine; phen = 1,10-phenanthroline), were synthesized. The L2– anions act as tri- and tetradentate ligands to bind to adjacent Zn(II) centers through carboxylate groups in µ1-η1:η0, µ1-η1:η1, µ2-η1:η1 and µ2-η2:η0 coordination fashions, respectively, forming binuclear units. Compound 1 has a chain structure composed of these dinuclear units, which is further extended via the bridging bipy molecules to afford a two-dimensional structure. Compound 2 features two binuclear structural units. The topological analysis of compound 1 reveals a (3,4,4,5)-connected net with the point symbol of {43‧62‧8}{43}{44‧62}{44‧66}. The fluorescence measurements have shown that compounds 1 and 2 present blue and blue-green fluorescence with emission maxima at 406 nm and 480 nm, respectively, which are ascribed to intra-ligand transitions.