| Coordination polymers have attracted much attention from chemists andmaterial scientists due to their potential applications and fascinating structuraldiversities. It is well known that coordination polymers are crystallinecoordination-based compounds in which metallic centres are bridged via organicmultitopic ligands to form multi-dimensional networks; therefore, the ligand is thekey factor for manipulating the topologies of coordination polymers. Up to now,many new flexible or rigid ligands have been explored and assembled intocoordination polymers. Among these ligands, N-containing heterocyclic ligands havebecome excellent candidates for constructing coordination polymers with structurevarieties. Moreover, the rational design and controlled synthesis of coordinationpolymers with different topologies and functions has attracted considerable attentionin crystal engineering. It is noted that hydrothermal/solvothermal synthesis is one ofthe most effective ways for the synthesis of zeolites, coordination polymers or otherinorganic-organic materials. However, the mechanism during the reaction process isvery complicated since it involves many reaction factors, including the ratio of thestarting materials, temperature, pressure and pH, which have significant influenceson the final products.In this paper, we have prepared six new coordination polymers usingN-containing heterocyclic ligands under hydrothermal/solvothermal conditions. Thetopology and properties of these compounds will be discussed. The researchpresented herein focuses primarily on the following four aspects:1. Two1D coordination polymers Cu2I(C6N3H4)2(1) and CuII(C6N3H4)2·H2O (2)based on benzotriazole (Bta) have been hydrothermally synthesized by controlling the crystallization temperature under H2O-NH3·H2O conditions.In compound1, there are two types of1D {-Cu-N=N-N-}nchains areinterconnected to build a1D tube along c-axis. And it is rare that the Cu(I) ionsabove adopt three types of coordination modes as linear, triangular, and tetrahedralgeometry in compound1. Moreover, compound1exhibits a strong luminescenceband peaking at619nm upon excitation at403nm. In the reaction, temperatureshould be an important factor in controlling the reduction of Cu(II) ions into Cu(I).In compound2, each Cu atom adopts quadrilateral coordination geometry, withfour N atoms from four Bta-c ligands. Moreover, the quadrilateral building units areconnected with each other by the Bta-c ligands, forming an infinite1D chain alongb-axis. Therefore, these1D chains interact with each other through π-π interactionsof the Bta-c ligands to construct a2D layer structure.2. A new copper(I) imidazolate metal-organic framework, Cu2[bbimb](3), hasbeen synthesized by solvothermal reaction of Cu(NO3)2·3H2O and1,3-bis(2-benzimidazol)benzene (H2bbimb) in an ammonium/methanol mixturesystem.For3, the temperature should be an important factor in controlling the reductionof Cu(II) ions into Cu(I). From the perspective of network topology, the linearlycoordinated Cu atoms serve to replace the O2-bridges in traditional zeolites, and thebbimb2-ligands act as tetrahedral nodes. Thus, compound3represents a3D4-connected net with zeolite ABW topology.3. Compound4has been hydrothermally synthesized by using5,5'-(1H-imidazole-4,5-diyl)bis(1H-tetrazole)(H3IBT) as organic ligand, and itpresents a three-dimensional supermolecular structure, which are connected by themononuclear [Co4(C5N10H2)4(H2O)8] square molecules through hydrogen bonds.4. Two novel coordination polymers with different structures Cu(C4N2H3Br)Cl(5) and Cu(C4N2H3Br)(6) have been synthesized under ethanol system by changingthe molar ration of the reactants. Copper(II) ions was reduced to copper(I) during the synthesis of compound5.In summary, we have prepared a series of coordination polymers usingN-containing ligands under hydrothermal/solvothermal conditions. The resultsdescribed herein illustrate the remarkable structural diversity afforded bycoordination networks constructed from flexible and multifunctional N-containingligands. Furthermore, we have investigated the effects of temperature, metal ions,and various synthetic strategies on the structures of coordination polymers.
|
PDF Full Text Request