Two 2D Co(II)/Mn(II) coordination polymers based on the quinoline-2,3-dicarboxylate ligand: synthesis, crystal structure, and fluorescence properties

A pair of two-dimensional (2D) isostructural coordination polymers (CPs), {[Co(2,3-qldc)(H2O)]} n (1) and {[Mn(2,3-qldc)(H2O)]} n (2), where 2,3-H2qldc = quinoline-2,3-dicarboxylic acid, were hydrothermally synthesized and characterized through IR spectroscopy, elemental and thermal analysis, power X-ray diffraction, and single-crystal X-ray diffraction. The results have revealed that the fully deprotonated 2,3-H2qldc ligand connects the Co(II)/Mn(II) atoms with a μ 3-bridge to form a square-wave 2D network, which is further extended into 3D stacks through O–H···O, C–H···O hydrogen bonds and π···π stacking interactions. Topologically, 1 or 2 can be simplified as a 4-connected sql type with a Schläfli symbol {44·62} and a Shubnikov tetragonal plane net, or as a 3-connected fes type with a Schläfli symbol {4·82} and a Shubnikov plane net. The thermal stability and the solid state fluorescence properties of 1 and 2 were investigated.