Effects of the size of aromatic chelate ligands and d10 metal ions on the structures of dicarboxylate complexes: From dinuclear molecule to helical chains and 2D network

Four new mixed-ligand complexes, namely [Zn2(pam)2(2,2′-bpy)2] (1), [Cd(pam)(2,2′-bpy)2]n (2), [Zn(pam)(phen)]n (3) and [Cd (pam)(phen)]n · 0.5n CH3CH2OH · 0.5nH2O (4) (H2pam = pamoic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydro(solvo)thermal conditions. Complex 1 possesses a discrete dinuclear metallamacrocyclic structure. Complex 2 is a 1D homochiral helical coordination polymer that is built from achiral components, whereas 3 displays a 1D helical chain structure. 4 is an unusual 2D double-layered structure generated by π ⋯ π interactions of two 2D networks. The structural differences of these complexes are mainly due to the differences of the size of the rigid aromatic chelate ligands and d10 metal ions. It appears that the chelate ligands and metal ions of the larger size favor the formation of high-dimensional structures, whereas those of the smaller size favor the formation of low-dimensional structures in the present system. The photoluminescence and thermal stability of these complexes were investigated.