Preparation And Properties Of Triazolyl Aromatic Carboxylic Acid Complexes

In this paper,we designed and synthesized a bifunctional semi-rigid ligand with 1,2,4-triazole and carboxylic groups,3,5-bis(4H-1,2,4-triazol-4-yl)benzoic acid(HL).Seven novel coordination.polymers,namely,{[Co2L2(SO4)(H2O)]·2H2O}n(1),{[Zn(L)(NO3)]·(H2O)}n(2),{[Zn(L)2]·2H2O}}(3),{Zn2(fum)(L)2}n(4),{[Cd2(L)(1,3,5-btc)(H2O)3]·3H2O}}(5),{[Cd2(L)2(1,2,4,5-btec)(H2O)2]·2H2O})(6),{[Ag2L]·guest} n(7),were synthesized based on different transition metal salts under solvothermal conditions.Complexes 1-7 were characterized by Single crystal X-ray diffraction,elemental analysis,infrared spectroscopy,powder X-ray diffraction and thermogravimetric analysis.Complex 1 was synthesized by HL and cobalt sulfate,the carboxyl group in which is not involved in the coordination.Co(II)were six-connected with triazole groups of the ligand,leading to a 2D 4,6L66 topological layer structure.Both 2 and 3 were constructed by zinc nitrate and Zn(II)atoms in the two complexes were all four connected.The main difference between 2 and 3 was the presence of lanthanum oxide as template in the synthesis of 3.In 3,one triazole of ligand was not coordinated with metals to form a 2D sql grid structure,which was completely different from the 3,4,L88 topological honeycomb layers structure in 2.Complex 4 was synthesized by the coordination of ligand HL and zinc nitrate in the presence of fumaric acid as the auxiliary ligand.In 4,the auxiliary ligands link the adjacent layers as pillars to generate a 3D 3,4L88 penetrating structure.Complexes 5 and 6 are constructed from cadmium n itrate,the involvement of different auxiliary ligands resulting different final structures.Complex 5 with 1,3,5-benzenetricarboxylic acid as the auxiliary ligand exhibits a 3D 3,3,3,6T3 topological structure.Complex 6 with 1,2,4,5-benzenetetracarboxylic acid shows a same 3D penetrating structure as complex 4.Complex 7 was synthesized by silver nitrate,showing a 3D sqc889 topological structure with Ag(I)as 3-connected point.The experiments also show that the fluorescence of complexes 2-6 can effectively be quenched by nitrobenzene,indicating their potential application as aromatic nitro compounds sensing materials.Moreover,the selective magnetic and fluorescence investigations were also conducted on the other 10 complexes 8-17 synthesized previously in our group.The magnetic properties results of Co based complexes 8-11 show that complex 8 has frequency dependence behavior and complex 10 has antiferromagnetic behavior.The fluorescence of Zn based complexes 12-17 could be quenched by nitrobenzene,which might have potential application for identifying aromatic nitro compounds.