Photoluminescent metal(II)-organic complexes with two distinct atropisomeric units from axially prochiral ligands through C–H⋯O hydrogen bonds (M = zinc, cobalt, nickel)

By taking advantage of rich-electron modification of pyridine-3,5-dicarboxylates, three photoluminescent isostructural metal-organic complexes, namely, [M(Hsmpdc)2(H2O)4] · 6H2O (smpdc = 2,6-dimethyl-4-(thiophen-2-yl)pyridine-3,5-dicarboxylate, M = Zn (1), Co (2) and Ni (3)), were synthesized and characterized by single crystal X-ray analyses. There are interesting hydrogen-bonded M2+(H2O)8 ionic clusters in the structures of title compounds. And of the most interesting is that S- and R-atropisomeric units are constructed from axially prochiral organic ligands through C–H⋯O hydrogen bonds. Strong photoluminescent emission at 543 nm with obvious red shift might make compound 1 a potentially photoactive solid-state material for its thermal and chemical stability.