Synthesis, structure and luminescent properties of two three-dimensional d10 metal complexes constructed from pyridine-3,4-dicarboxylic acid with new network topologies

Two novel three-dimensional d10 metal coordination polymers [Zn2(pydc)2(DMF)3]n (1) and [Cd2(pydc)2(H2O)]n (2) (H2pydc=pyridine-3,4-dicarboxylic acid, DMF=N,N-dimethylformamide) have been synthesized under solvothermal and hydrothermal conditions, and characterized by elemental analysis, IR, TG analysis and single crystal X-ray diffraction. Compound 1 exhibits a complex three-dimensional framework containing one-dimensional elliptic channels occupied by coordinated DMF molecules. In complex 2, adjacent sheets constructed by carboxyl-bridged Cd–O–Cd chains are pillared by pydc ligands into a three-dimensional network. From a topological point of view, the two three-dimensional nets display (3,4)-connected (6.82)2(6.85) and 4-connected (4.85)(42.6.83)2(43.62.8) topologies, respectively, which are unprecedented within coordination frames. Furthermore, both compounds show intense fluorescent emissions upon photoexcitation at room temperature.