Syntheses, Structures And Property Study Of Coordination Polymers Based On A V-shaped Bis-imidazole Ligand

The synthesis of coordination polymers with structural diversities and excellentproperties as well as futher application investigation based on them is a researchfrontier of inorganic chemistry and supramolecular chemistry. In this paper, aV-shaped1,1’-(5-methyl-1,3-phenylene)bis(1H-imidazole)(B-im) selected as a mainligand and the carboxylic acids with different symmetric structures and functionalgroups selected as auxiliary ligands were used to synthesize eleven novelcoordination polymers, namely,[Ni(B-im)(Br-a)Cl]n·nH2O (1),[Zn(B-im)(Br-a)2]n·nCH3OH (2),[Ni(B-im)(I-a)(H2O)2]n·0.5nH2O (3),[Co(B-im)(I-a)(H2O)2]n·0.5nH2O (4),[Ni(B-im)(I-a)(H2O)2]n(5),[Mn2(B-im)2(I-a)2]n·2nH2O (6),[Ni(B-im)(M-a)(H2O)2]n(7),[Co(B-im)(M-a)(H2O)2]n(8),[Zn(B-im)(M-a)]n·nH2O (9),[Co2(B-im)2(M-a)2]n·nH2O(10) and [Co3(B-im)4(T-a)2(H2O)2]n·2.5nH2O (11)[5-Bromonicotinic acid (Br-a),Isophthalic acid (I-a),5-Methylisophthalic acid (M-a) and Trimesic acid (T-a)]through hydro-or sovlothermal reactions. The eleven synthesized coordinationpolymers were charactered through single crystal X-ray diffraction analyses andthermal stability analyses, and the fluorescent, UV-vis spectra and magneticproperties of some complexes were all studied.Complex1is a one-dimensional coordination polymer with nanotube. ThreeV-shaped B-im ligand molecules link with three nickel(II) ions to form a ternarymetal-organic ring with a diameter of about12. The metal-organic rings are furtherbridged into a one-dimensional nanotube through the coordination of ligands Br-awith the nickel(II) nodes. The structure is novel, and up to now only a few of caseswith similar nanotube structures designed coordination chemistry has been reported.The coordination polymer2with good fluorescence property was synthesized by theassembly of zinc(II) ions with ligands B-im and Br-a. The coordination polymerfeatures one-dimensional chain structures. Complexes3and4are isomorphisms.They are circular tubular coordination polymers which contain the9.4×18.32 quarternary metallorganic rings forming by four metal ions, two V-shaped B-imligands and two V-shaped carboxylic acid ligands I-a. Very interestingly, the adjacentmetal-organic rings in the same chain share two metal ions as common nodes toconnect with each other, with the dihedral angle between two adjacent quarternarymetal planes being115.7°. Particularly, when only changed the solvent and reactiontemperature used in the synthesis of complex3, complex5with obviously differentstructure was obtained. Complex5consists of the double chains which are extendedinto three-dimensional supramolecular structure by interchain π···π interactions.Coordination polymer6is a two-dimensional layer structure. In each layer, theligands B-im and I-a bridge manganese(II) ions into rare three-stranded polymericchains which are connected together again by the other half of I-a ligands. Whenchosen the carboxylic acid M-a as an auxiliary ligand, coordination polymers710were synthesized. Complexes7and8are isomorphisms, and their structures aresimilar to the double chains of complex5. In coordination polymer9, zinc(II) ions arebridged by carboxylic acid ligands M-a to form left-and right-handed spiral chainswhich are further bridged by ligands B-im to form a two-dimensional meso-layerstructure. When adjusted the reaction conditions of complex8, namely, by changingthe solvent and the reaction temperature, Coordination polymer10with differentstructure formed. The coordination polymer10is a two-dimensional layer structurewhich contains quaternary metal-organic ring units Co4(M-a)4. When selected thetrimesic acid T-a as an auxiliary ligand to assemble with Co(II) ions, coordinationpolymer11which has novel two-dimensional network was obtained. The thickness ofthe layer in complex11is about36.7.In the paper we systematically studied the crystal structure, purity and thermalstability of coordination polymers111. Meanwhile, the fluorescence performance ofzinc(II) complexes2and8, the solid UV-vis spectra of complexes4,8,10and11,and the magnetism of complexes46were investigated.