Study On Synthesis And Properties Of Rare Earth Neodymium-Carboxylic Acid Complexes

Rare earth elements was known as "the material of the 21st century",it has a unique physical and chemical properties.China has a large amount of rare earth which has a profound impact on economic and social development.Neodymium as a member of the rare earth elements has some incomparable spectroscopic properties and it's complexes with organic ligands in probe light-emitting materials[3],superconducting materials,structure,molecular sieve,catalytic and biological activity,and other fields have caught people's widely attention.In this paper,three neodymium complexes have been synthesized with carboxylic acid compound by hydrothermal.For exploring the structure and property,much work have been done including the three part as follows:1.A neodymium coordination polymer[Nd2(C4H4O4)3·2H2O]n has been synthesized with succinic acid and Nd(NO3)3·6H2O under hydrothermal condition,and characterized by IR,UV,fluorescence,TG-DTA,electrochemistry and X-ray single-crystal diffraction.The crystal belongs to the triclinic system,a = 0.784 5(3)nm,b = 0.811 4(3)nm,c = 1.422 7(5)nm,? =96.933(5)°,? = 97.023(5)°,? = 103.513(5)°,Z =2 and V=0.863 4(5)nm3,with a nine-coordinated of the neodymium forming a distorted tetradecahedral.The polymer emits yellow-green luminescence at 367 nm(ex=326nm),duing to the charge transfer ligand to the central metal.2.A neodymium coordination polymer[Nd2(p-C8H4O4)(o-C8H4O4)2·4H2O]n has been synthesized with terephthalic acid,phthalic acid and Nd(N03)3·6H2O using hydrothermal method,and characterized by IR,UV,fluorescence,TG-DTA,electrochemistry and X-ray single-crystal diffraction.The complex is crystallized in triclinic space group P-1.Each neodymium coordination is arounded by nine oxygen atoms,a = 0.62078(4)nm,b =0.88862(5)nm,c = 2.52194(14)nm,a =88.605(2)°,p = 87.090(2)°,?? = 70.719(2)°,Z=2,V=1.31143(13)nm3.The results show that yellow-green luminescence could been observed at 391 nm(ex=305nm)for the complex.Cyclic voltammetry results of the compound show that the compound has a couple of irreversible redox peak in the range of-0.3?0.3 V,indicating that the polymer was corresponded to the unusual Nd(III)/Nd(V).3.A neodymium coordination polymer[Nd2(C10H4O8)(C10H2O8)-2H2O]n has been synthesized with benzenetetracarboxylic anhydride and Nd(NO3)3·6H2O under hydrothermal condition,and characterized by IR,UV,fluorescence,TG-DTA,electrochemistry and X-ray single-crystal diffraction.The complex is a three-dimensional framework containing nine-coordinate neodymium centers.There are two kinds of carboxylic groups,protonated carboxylic groups and deprotonated in the structure.The pyromellitic acid which contains protonated carboxylic groups acts as bridge to link six neodymium atoms,including two protonated carboxylic groups and two deprotonated carboxylic group,each protonated carboxylic group coordinates to one neodymium atom and each deprotonated carboxylic group connects to two neodymium atoms.The pyromellitic acid that have no protonated carboxylic groups also acts as bridge to link six neodymium atoms,the two para-carboxylate groups adopt a bidentate chelating mode coordinating to the same neodymium atom while the other two para-carboxylate groups adopt a bidentate chelating-bridging mode connecting two neodymium atoms.