Dinuclear complexes of Mn, Co, Zn and Cd assembled with 1,4-cyclohexanedicarboxylate: synthesis, crystal structures and acetonitrile fluorescence sensing properties

Four dinuclear complexes: [Mn-2(H2O)(2)(chdc)(2)(bipy)(2)],1; [Co-2(H2O)(2)(chdc)(2)(bipy)(2)]center dot H2O,2; [Zn-2(H2O)(2)(chdc)(2)(bipy)(2)]center dot H2O,3; and [Cd-2(H2O)(2)(chdc)(2)(bipy)(2)]center dot H2O,4; chdc =e,a-cis-1,4,cyclohexanedicarboxylate and bipy = 2,2 '-bipyridine, were attained as single crystals under ambient conditions. Crystallographic studies show that complexes1,2and3are isostructural and crystallize in the monoclinic system with theP2(1)/cspace group. The metal centers in these complexes are hexa-coordinated with a distorted octahedral coordination sphere. Complex4crystallizes in the triclinic system with the P (1) over bar space group; in this compound, the metal centers are hepta-coordinated and their coordination sphere is distorted-capped trigonal prismatic. Magnetic property measurements reveal that complexes1and2exhibit weak antiferromagnetic ordering. Complex4displays solid-state blue emission properties and a highly sensitive response to acetonitrile in water based on turn-on fluorescence with a low detection limit of 1.1 mu M and selectivity over common polar organic solvents.