Syntheses, Structures And Properties Of Coordination Polymers With A Specific Topology

The design and construction of new functional coordination polymers have been one of the most intensive research topic in coordination chemistry, supramolecular chemistry and crystal engineering due to their novel topological structures and potential applications in the optical,electrical,magnetism,catalytic and molecular recognition fields . Based on these backgrounds, we are beginning our work to challenge this charming field.Variety of carboxylic acid ligands, versatile coordination modes , therefore, The use of crystal engineering principles, Metal ions and multi-carboxylic acid as structure-based element of metal organic coordination polymer design and synthesis ,which have been gotten rapid developed and has achieved many remarkable results .however , the reported coordination polymers are mostly constructed by rigid polycarboxylate ligands, but studies about the flexible polycarboxylate ligands and semi-rigid V-shaped polycarboxylate ligands are relatively few. Flexible multi-carboxylate aromatic ligand,Since the two aromatic rings have a certain interval between the groups,which can occur rotate to accommodate the formation of coordination bonds among groups,So these aromatic ring ligand both rigid and flexible, However, many flexible carboxylic aromatic ligand based transition metal complexes constructed are relatively few.The flexible ligand as coordination polymers of building units because of their conformation and coordination mode of coordination variability, Provides more possibilities for designing and synthesizing a novel structure and properties of coordination polymers.On the other hand, Metal chelates in which the metal ion is coordinatively unsaturated can act as electron acceptors and yield coordinative compounds with molecules including N atom being electron donors. To our knowledge, the molecules including N atom have mainly consisted of a series of pyridines ,but a series of imidazoles have been reported relatively few .we designed and synthesized a series of additional ligands including bix(1,4-bis(imidazol-1-ylmethyl)benzene), mbix(1,3-bis(imidazol-1-ylmethyl)benzene),obix(1,2-bis(imidazol-1- ylmethyl)benzene),bimb(4,4'-bis(imidazol-1-ylmethyl)biphenyl).In this work, 15 coordination polymers have been designed and synthesized with Zn(II), Co(II),Cd(II) ions and aromatic carboxylates by hydrothermal synthesis method, the structures and properties of the crystals have also been characterized. The influences of synthesis metal ion ,temperature, ligands structure and pH value based on the relationship between reaction conditions and products.Meanwhile, one of the five complexes were measured second-order nonlinear optical properties, we further discussed the relationship between second-order molecular polarizability and ferroelectricity and molecular structure as well as crystal structure.