Substituent effects of polycarboxylate ligands on the construction of Cd(II) coordination polymers incorporating bis-pyridyl-bis-amide ligands

Abstract

The synthesis, structures and properties of five new coordination polymers containing isomeric N,N′-di(pyridyl)suberoamide and polycarboxylate ligands, {[Cd(1,3-BDC)(L1)]·H2O}n [L1=N,N′-di(3-pyridyl)suberoamide; 1,3-H2BDC=benzene-1,3-dicarboxylic Acid] 1; [Cd(5-OH-IPA)(L1)]n (5-OH-IPA=5-hydroxyisophthalic Acid), 2; {[Cd3(1,3,5-BTC)2(L1)3(H2O)3]·8H2O}n (1,3,5-H3BTC=1,3,5-benzenetricarboxylic Acid), 3; [Cd(5-Br-IPA)(L2)]n [L2=N,N′-di(4-pyridyl)suberoamide; 5-Br-H2IPA=5-bromoisophthalic Acid], 4; [Cd(5-tert-IPA)(L2)0.5]n (5-tert-H2IPA=5-tert-butylisophthalic acid), 5, are reported, which have been characterized by single crystal X-ray diffraction. Complexes 1 and 2 show 2D double layers with the 3,5L2 topology and 3 reveals a 3D structure with the rare 3,4,4T90 topology. Complex 4 is a twofold interpenetrated 2D layer with a 2,6L1 topology and 5 shows a 3D coordination network with a rare 4,6T136 topology. In 5, the L2 ligand adopts a unique tetradentate bonding mode through two pyridyl nitrogen and two amide oxygen atoms. The structure-directing role roles of the substituent groups on the polycarboxylate ligands in determining the structural diversity are discussed. Their thermal and luminescent properties are also investigated.