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 (H 2 O) 2 (chdc) 2 (bipy) 2 ], 1 ; [Co 2 (H 2 O) 2 (chdc) 2 (bipy) 2 ]·H 2 O, 2 ; [Zn 2 (H 2 O) 2 (chdc) 2 (bipy) 2 ]·H 2 O, 3 ; and [Cd 2 (H 2 O) 2 (chdc) 2 (bipy) 2 ]·H 2 O, 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 P 2 1 / 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 1&cmb.macr; 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. Selective and reversible fluorescence sensing of acetonitrile in water by [Cd 2 (H 2 O) 2 (chdc) 2 (bipy) 2 ]·H 2 O with a detection limit of 1.1 × 10 −6 M.