Influence of N-donor ancillary ligands on the structures of three cadmium(II) complexes with L-shaped carboxylate ligand

Abstract This work presents a systematic investigation on reactions of cadmium nitrate with L-shaped 1-carboxymethylpyridinium-4-carboxylate (L) ligand in the presence of three different N-donor ancillary ligands 2,2′-bipyridine (2,2′-bipy), 1,10-phenanthroline (1,10-phen), and 4,4′-bipyridine (4,4′-bipy). Three new cadmium(II) complexes, namely, [Cd(L) 2 (H 2 O) 4 ] ( 1 ), [Cd(L) 2 (1,10-phen)]·7.54H 2 O ( 2 ), and [Cd(L) 2 (H 2 O)]·2H 2 O ( 3 ), were obtained and characterized by single-crystal X-ray diffraction, as well as IR spectroscopy. Structure analysis shows only 1,10-phen ligand takes part in coordination in complex 2 . Complex 1 possesses a 3D hydrogen-bonded supramolecular network, which are constructed by the linkage of neutral mononuclear [Cd(L) 2 (H 2 O) 4 ] molecules via abundant O–H⋯O hydrogen-bonds. Compared with 1 , complex 2 features a 2D layer structure, which is made up of 1D tubes consisting of helical chains via π-π interactions. Complex 3 displays a 3D metal-organic framework with {6 5 ·8} topology. The results reveal that different N-donor auxiliary ligands have a subtle effect on the final structures of coordination supramolecules. Moreover, the solid photoluminescent property of 2 was also studied at room temperature.