Synthesis, crystal structures and luminescent properties of zinc(II) and cadmium(II) complexes with N,N-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide

The assembly of Zn(II) and Cd(II) centers with different counter anions and XIL ligand (XIL = N,N-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide) gave rise to three new coordination complexes, Zn(XIL)Cl2·DMF (1), [Zn(XIL)2(SCN)2·2H2O]n (2) and [Cd(XIL)2(SCN)2·2H2O]n (3). Complex 1 exists as a centrosymmetric dimer with XIL as exo-bidentate ligand bridging two ZnCl2 units. The dimer forms a 3D supermolecular structure through the hydrogen bonding and strong π–π stacking interactions. Complexes 2 and 3 are iso-structural with a 1D double-chain configuration with XIL as bridging ligand and SCN− as terminal ligand. Among the three complexes, complex 1 exhibits the strongest photoluminescence.