| In recent years, coordination polymers have been increasingly focused, not only because of their intriguing structures and topologies, but also for their potential applications in many fields, such as luminescence, gas adsorption, magnetism, catalysis and so on. As a result, a variety of complexes with abundant structural features and useful properties have been discussed in some comprehensive reviews. One of the effective strategies for constructing coordination polymers is to select suitable multidentate organic ligands to link metal centers into infinite metal-organic frameworks. Among the successfully employed organic ligands, N-and O-donor multidentate flexible ligands are regarded as excellent building blocks with the aim to acquire desirable metal-organic frameworks.In this paper, our work includes two parts as follow:1. We designed and synthesized a new imidazol-1-yl and carboxylate-containing flexible ligand:5-(imidazol-1-ylmethyl)isophthalic acid (H2L1) as a building block for construction of coordination polymers with diverse structures. Nine new mental-organic polymers:[CoLl(DMF)]n (1),[CoL1(bpa)0.5]n (2),{[CoL1(bpe)0.5]·(H20)2}n (3),{[CoL1(bpy)0.5]·(H2O)}n (4),[CdL1(bpa)0.5]n (5),[ZnL1(bpe)0.5]n (6),{[CuL1(phen)]·(H2O)2}n (7),{[CuL1(bpe)(H2O)]·(H2O)3}n (8),{[NiL1(bpe)(H2O)]·(H2O)3}n (9)(bpa=1,2-bis(4-pyridyl)ethane, bpe=1,2-di(pyridine-4-yl)ethylene, bpy=4,4’-bipyridine, phen=1,10-phenanthroline) were obtained by the reactions of H2L1and ancillary nitrogen-containing ligands with divalent metal salts. The structures of these polymers have been characterized by IR, elemental analysis, single-crystal X-ray diffraction, thermal stability and UV properties.Due to the two carboxylate groups and the flexible imidazol-1-ylmethyl arm, H2L1could lead the coordination polymers exhibit various types of architectures. In complex1, each LI2-ligand bridges two Co(â…¡) centers to form the right-handed (Co-L2-)n helical chains. Complexes2and3are isostructural, exhibiting two-fold2Dâ†'3D interpentration framework. Each L12-anion bridges three Cd centers to give a ID infinite zig-zag chain [Co(Ll)]n. These chains are further connected by crossed ancillary ligands generating a2D layer. X-ray structural analysis revealed that complex4is a two-fold3D interpentration framework. In the Complex5, the Cd unit is first linked by nitrogen atoms and the three oxygen atoms of the4-carboxyl group to form (R) right-and (L) left-handed helical channels, such layers are further linked by the bpa to give a3D metal-organic framework, In the complexes7,8and9, the2D double layers are further associated together through π…πinteractions from ancillary nitrogen ligands to lead to a3D supramolecular structure.2. Based on H2L1, we designed and synthesized another new imidazol-1-yl and carboxylate-containing ligand:5-(2-methylimidazol-1-ylmethyl) isophthalic acid (H2L2). Three novel metal-organic frameworks, namely,[CoL2(H2O)]n (10),[ZnL2(H2O)]n (11),[CuL2(DMF)]n (12) were obtained by the solvothermally reaction of H2L2with different divalent metal salts.Complex10is a two-fold3D interpentration framework, which has two different chiral helical chains. Complexes11and10are isostructural. In the compex12, two Cu atoms are linked together by two μ2-η-:η--bridging carboxylate groups to form a dinuclear secondary building unit (SBU)[Cu2(CO2)4]. The3D framework is constructed by linking these SBU through the shared L22-... |
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