Synthesis, Structures, And Properties Of Metal-Organic Frameworks Based On Nitrogen Heterocyclic Ring And Carboxyl Acid Mixed-ligands

Metal-organic frameworks as a kind of functional material have been applicated in gas separation and adsorption, catalysis and fluorescence chemical sensing and so on. Therefore,the design of metal-organic frameworks with novel structure and specific function become a hotspot in the research of inorganic chemistry. Many factors, such as metal atom center,organic ligand, reaction temperature, solvent composition, p H value, etc., affect the structures of the as-synthesized compounds. Therefore, the directional synthesis of metal-organic frameworks with specific structure or function is still a great technical challenge.In this paper, we designed and synthesized different types of organic ligands, and chose different solvents and auxiliary ligands to build novel network topology structures of metal-organic frameworks. We systematically studied and analysed the structures and related properties of these compounds.(1) We designed and synthesized four kinds of metal-organic frameworks with different space structures, such as Co(aip)(py)3(1), Co(aip)(4,4'-bipy)(2), Mn(aip)(4,4'-bipy)(3) and Mn(aip)(dptz)(4). We used 5-azidoisophthalic acid as organic ligand, pyridine as organic amine, and cobalt nitrate as ligands to form metal nodes. Through carboxylate ligands linking with different metal nodes, a one dimensional(1D) chain molecular structure of compound 1formed. Subsequently, compound 2 with two dimensional(2D) layered structure was synthesized by the modulation of the second ligands. On this basis, the size of the metal ions and the second ligands were further changed and compounds 3 and 4 with 2D layered structure were synthesized. In this paper, the thermal stability of compounds 1-4 were studied and variable temperature magnetic susceptibility tests were acheieved. The results showed that the four compounds performed weak antiferromagnetic property.(2) We have designed a neutral ligand, N, N'-sulfonyldiimidazole, coordinated with the transition metal ions and different anions to adjust the structures of the metal-organic frameworks. We synthesized eleven kinds of polymers, such as [Zn(sdi)(NO3)2(H2O)](5),[Zn(sdi)2(NO3)2](6), [Co(sdi)2(NO3)2](7), [Cu(sdi)2(NO3)2]·2CO(CH3)2(8), [Mn(sdi)2(H2O)2]·2NO3(9), [Co(sdi)2(H2O)2]·2Cl O4(10), [Zn(sdi)(bdc)0.5(OCH3)(H2O)]·Cl O4·H2O(11),[Cd(sdi)(N3)2](12), [Mn(sdi)(N3)2](13), [Ni(sdi)2(SO4)](14) and [Cd(sdi)0.5(btc)(OCH3)](15).Structural analysis showed that the structures of the metal-organic frameworks changed from zero dimensional(0D) to three-dimensional(3D). Compound 5 contructed with [Zn(sdi)]2dimer showed 0D structure; compounds 6-11 showed 1D structure of a sealed ring; compound12 showed 2D structure with 63 topology meshes; compounds 13 and 14 showed 3D pcu topology; compound 15 is a 3D(65.8) Cd SO4 topology. We studied the magnetic property of compound 13 and the fluorescence properties of compound 5, 6, 11, 12 and 15.(3) We used the rigid ligand NBPDC mixed with three kinds of flexible ligands, bpp(1,3-bi(4-pyridyl) propane), bib(1,4-bis(imidazol) butane) and bip(1,5-bis(imidazol)pentane), to construct a series of coordination polymers. We choose1,4-bimb(1,4-bis(imidazol-1-ylmethyl)benzene), 1,3-bimb(1,3-bis(imidazol-1-ylmethyl)benzene) and 4,4'-bimbp(4,4'-(bis(imidazol- l-ylmethylene)) as one component of the mixed ligands. Eight kinds of metal-organic frameworks, such as [Mn(NBPDC)(1,4-bimb)]n(16),[Zn(NBPDC)(1,4-bimb)]n(17),[Cd(NBPDC)(1,4-bimb)]n(18),[Mn2(NBPDC)2(1,3-bimb)(H2O)]n(19),{Zn(NBPDC)(1,3-bimb)}n(20), [Cd2(NBPDC)2(1,3-bimb)2(H2O)]n(21),[Mn(NBPDC)(4,4'-bimbp)]n(22), [Cd2(NBPDC)2(4,4'-bimbp)2]n(23) have been synthesized.We have discussed the coordination modes and topologies of these metal-organic frameworks,and discussed the fluorescence and magnetic properties of the partical polymers.In this paper, the synthesis method of solvent heat was used to study the structure and properties of metal-organic frameworks The synthesis of compound 1-23 enriched the structure of the complexes and provided some experimental evidence for the exploration of the structure. The fluorescence and magnetic properties of the gained metal-organic frameworks were also explored.