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

Abstract

Four dinuclear complexes: [Mn₂(H₂O)₂(chdc)₂(bipy)₂], 1; [Co₂(H₂O)₂(chdc)₂(bipy)₂]·H₂O, 2; [Zn₂(H₂O)₂(chdc)₂(bipy)₂]·H₂O, 3; and [Cd₂(H₂O)₂(chdc)₂(bipy)₂]·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 complexes 1, 2 and 3 are isostructural and crystallize in the monoclinic system with the P2₁/c space group. The metal centers in these complexes are hexa-coordinated with a distorted octahedral coordination sphere. Complex 4 crystallizes in the triclinic system with the P 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 complexes 1 and 2 exhibit weak antiferromagnetic ordering. Complex 4 displays 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 μM and selectivity over common polar organic solvents.