Synthesis,Structures And Properties Of Coordination Complexes Based On N-heterocyclic Polycarboxylate Groups

Coordination polymers,which involve self-assembly of organic ligands with appropriate functional groups and metal ions with specific directionality and functionality,are a kind of infinite network structure hybrid inorganic-organic supermolecular materials.As a new type of hybrid materials,coordination polymers have potential application in magnetism,gas storage,interphase forcing,chemical sensing,electroluminescent,molecular recognition,the energy storage and transformation aspects.This paper designed and synthesized 18 new different coordination polymers with fluorescent or magnetic properties based on the main group metals(Ba2+)and transition metals(Mn2+,Fe2+,Co2+,Ni2+,Cu2+,Zn2+,Cd2+)with six kinds of different nitrogen heterocyclic carboxylic acid ligands.The structures of complexes are characterized by X-ray single crystal diffraction and we studied magnetic properties of coordination polymers containing metals(Fe2+,Co2+ Ni2+ and Mn2+)with unpair electron.In addition,we also studied fluorescent properties of the metal coordination polymers with d10 electronic configuration and the detection of metal ions and common anions.In this paper,we mainly discussed from the following four parts.1.Seven new complexes are synthesized and characterized by three asymmetric pyrazole carboxylic acid ligands with different metals.The different crystal structures are constructed by different coordination models of the ligands.Two kinds of complexes synthesized via L1 ligand show different coordination modes,which are ?3-?N,O1:?O1?:?O2 and ?2-?N,O1:?O2,respectively.While the three kinds of complexes synthesized by means of L2 ligand show the same coordination model,which is ?2-?N,O1:?O2,O2?.And two kinds of complexes contained L3 ligand show different coordination modes,which are ?3-?N,O1:?O2:?O3and ?2-?N,O1:?O3.With the increase of carboxyl,polynuclear complexes are easily formed.In addition,magnetic analysis showed that the tri-nuclear copper(II)complex 6 formed ligand L3 exist ferromagnetic interactions,while other complexes shows antiferromagnetic interactions.We also studied fluorescent properties of 3 and 4 complexes.In contrast to that of L2 ligand,both complexes have luminescence enhancement,which may be due to the combination of ligand and metal atoms enhanced ligands rigid and reduced the ligand energy loss caused by no radioactive decay.2.Two novel homogeneous complexes of cadmium and manganese were assembled by 1-(4-carboxybenz-yl)-1H-benzoim-idazole-5,6-dicarboxylic acid(H3cbic)ligand with high stability in water and high thermostability,showing 2D networks containing one dimensional left and right-handed double helical chains and topology symbols are(47.63).we found that complex 8 features the highly selective and ultrasensitive recognition for Fe3+ ion and have high quenching effect coefficient and the low detection limit(3.1×10-5)mol/L for Fe3+.Importantly,this system shows steady luminescence within the p H range from 6.0 to 14,which is broader than the reported MOF-based luminescent sensors for detecting Fe(III).Furthermore,a simple adsorption test demonstrated that a weak bond is formed between Fe3+ and the uncoordinated carboxyl group of complex 8.In addition,the magnetic properties of complex 9 were discussed and the results showed weak antiferromagnetic interactions between Mn(II)centers.3.Two complexes of cadmium and manganese were obtained from1-(4-carboxybenzyl)-2-propyl-1Himidazole-4,5-dicarboxylic acid(H3cpimda)under hydrothermal conditions.The H3 cpimda ligand was found to have partly lost one carboxylate group from imidazole-4,5-dicarboxylic acid and generated a new ligand,namely,1-(4-carboxybenzyl)-2-propyl-1H-imidazole-4-carboxylic acid(H2cpima).In the building process of cadmium complex 10,both ligands involved in coordination,forming a 2D structure with topology symbols of(43)2(46.66.83).While in the process of constructing manganese complex 11,only ligand cpima2-participated in coordination forming a simple 0D structure.At the same time,owing to imidazole rings and more carboxyl groups,there is a strong hydrogen bonding and weak interactions in complex 10.Thus,a 3D network is formed by these weak interactions of 2D structure.We found that fluorescence intensity of complex 10 is stronger than that of free ligand,which should be due to the ligand ?-? electron transfer between the ligands.In addition,the magnetic property of complex 11 is discussed and there are weak antiferromagnetic interactions between the metal centers of Mn(II).4.Seven complexes are assembled by 1,1'-(1,4-phenylenebis(methylene))bis(1H-pyrazole-3,5-dicar-boxylic acid)(H4L6)which fully deprotonated formed L4-.Ligands had five different coordination modes,in complexes 12?14 of iron(II),cobalt(II),nickel(II)with a 2D homogeneous structure.Also,manganese complex 15 had also a 2D structure.In the complexes 16?18 of barium,zinc and cadmium,16 and 18 are 3D structures and complex 17 is a 2D structure.The magnetic properties of complexes 12?14 have different behaviers,although they are isomorphism.Complexes 12 and 13 are antiferromagnetic and 14 with a nickel center representing ferromagnetic property.In addition,we also found that complex 16 has a highly recognition of Fe3+ and Cr2O72-ion in DMF solution.More importantly,it can distinguish Cr2O72-and Cr O42-ions in DMF solution.Compared with relevant literatures,complex 16 in the identification of Fe3+ and Cr2O72-ion has a lower detection limit and high quenching constants.In addition,the fluorescence properties of complex 17 are studied and found fluorescence emission of complex 17 attributed to electron transition between ligands(ILCT)by DFT calculation.