Syntheses, Characterization and Crystal Structures of Three New Copper(II) Complexes Based on N,N′-bis(4-pyridinecarboxamide)-1,4-butane and Three Different Aromatic Dicarboxylates

Abstract

Three new copper(II) complexes based on the flexible N,N’-bis(4-pyridinecarboxamide)-1,4-butane (4-dpyb) and three different aromatic dicarboxylic acids [5-methylisophthalic acid (5-H2MIP), 5-aminoisophthalic acid (5-H2AIP), pyridine-2,6-dicarboxylic acid (2,6-H2PDA)], [Cu(4-dpyb)(5-MIP)(H2O)]·H2O (1), [Cu(4-dpyb)(5-HAIP)2] (2), [Cu(4-dpyb)0.5(2,6-PDA)]·H2O (3), have been hydrothermally synthesized. X-ray diffraction analysis reveals that complex 1 is a 2 D grid polymeric layer constructed by the [Cu-4-dpyb] chains and [Cu-5-MIP] chains, and the adjacent layers are further linked by hydrogen bonding interactions to form a 3 D supramolecular structure. Complex 2 is a 3 D supramolecular network based on the polymer chain [Cu(5-HAIP)2]n, in which the discrete 4-dpyb ligands are dispersed. Complex 3 represents a polymer chain based on the μ 4 -bridging 4-dpyb ligand, in which 2,6-PDA only serves as a terminal chelating ligand. For complex 3, the neighboring chains are extended into a 3 D supramolecular structure by hydrogen bonding and π–π stacking interactions. In these complexes, the flexible bis-pyridyl-bis-amide ligands 4-dpyb show the μ 2 -bridging mode (for 1), non-coordinated mode (for 2) and μ 4 -bridging mode (for 3), respectively, and three kinds of aromatic dicarboxylate anions (5-MIP, 5-HAIP and 2,6-PDA) also adopt three different coordination modes. The different coordination modes of ligands 4-dpyb and three dicarboxylates play important roles in the construction of final structures for title complexes. In addition, the thermal stabilities and fluorescent properties of complexes 1–3 have also been investigated. Three new 3 D supramolecular complexes based on 2 D polymer layers or 1 D chains, [Cu(4-dpyb)(5-MIP)(H2O)]·H2O (1), [Cu(4-dpyb)(5-HAIP)2] (2), [Cu(4-dpyb)0.5(2,6-PDA)]·H2O (3), have been hydrothermally synthesized. The different coordination modes of ligands 4-dpyb and three dicarboxylates play important roles in the construction of final structures for title complexes.