Four new complexes based on 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) and four bis-pyridyl-bis-amide ligands with various spacers (3-bpye = N,N′-bis(3-pyridinecarboxamide)-1,2-ethane; 3-bpfp = bis(3-pyridylformyl)piperazine; 3-bpcd = N,N′-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide; and 3-bpcb = N,N′-bis(3-pyridinecarboxamide)-1,4-benzene), namely [Cu2(1,4-NDC)2(3-bpye)(H2O)] (1), [Cu(1,4-NDC)(3-bpfp)0.5] (2), [Cu3(1,4-NDC)3(3-bpcd)3]·2H2O (3), and [Cu(1,4-NDC)(3-bpcb)] (4), have been hydrothermally synthesized. Complex 1 is a 3D coordination network and represents an 8-connected {420.68} topology. Complex 2 shows a 2-fold interpenetrating 3D architecture with a 6-connected {412.63} topology. Complexes 3 and 4 possess similar 2D sql layers with the {44.62} topology, but the coordination modes of 1,4-NDC ligands and the conformations of the two bis-pyridyl-bis-amide ligands are different. The adjacent layers for 3 and 4 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. The successful assemblies of complexes 1–4 imply that by using the different bis-pyridyl-bis-amide ligands with diverse spacers can produce diverse metal–organic networks. Furthermore, the fluorescence and photocatalytic properties of complexes 1–4 have been investigated.
Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds