Structural diversity, topology and luminescent properties of a two-dimensional Cd(II) coordination polymer incorporating 4,4′-dipyridyl and 4,4′-sulfonyldibenzoic acid

A new Cd(II) derivative, [Cd2(H2O)4(bipy)(sdba)2]∙10H2O (1), is synthesized hydro(solvo)thermally by the combination of divalent cadmium nitrate tetrahydrate as metal salt, an N-donor ancillary ligand 4,4′-bipyridine (bipy), and the flexible aromatic carboxylate, 4,4′-sulfonyldibenzoic acid (sdba), as organic linker. Single crystal X-ray diffraction analysis reveals that the Cd(II) atoms show a distorted trigonal bipyramidal environment. In the asymmetric unit, both the carboxylate and the N-donor connectors bridge pairs of cadmium ions; this ultimately leads to the formation of a set of undulated sheets formed by fused rings comprising six cadmium centers, two bipy and four sdba ligands. Considering the cadmium ions as nodes and the ligands as connectors, the structure can be described as a stack of 3-c uninodal nets of the type hcb, with point symbol {44.62} and vertex symbol [6.6.6]. The encapsulation of the Cd(II) derivative displays a moderate luminescent property.