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

The metal-organic coordination compounds refer to a type of complexes owing periodic network structures that self-assembly by one or more inorganic metal ions or metal clusters through bridging,or chelating organic ligands.Coordination compounds both have the advantages of inorganic and organic compounds,such as high surface areas and thermal stabilities.The potential applications of metal-organic coordination compounds in magnetics,optical properties,selective adsorption,catalysis,and sensing have become one of the research hotspots in the field of materials science.In this dissertation,26 novel coordination compounds with different luminescent or magnetic properties were designed and synthesized based on the main group metals,transition metals and rare earth metals with four different N-heterocyclic carboxylic acid ligands.The relationship between the structures and properties of these complexes,the changes of the structure properties of different complex metals,different pH values,and different coordination anions were both studied.The complexes were also characterized by infrared,single crystal X-ray diffraction and elemental analysis methods,besides,powder diffraction experiments were done to determine their purities.Their thermal stability and luminescent/magnetic properties were analyzed.In this paper,we mainly discuss the following four parts:1?Based on 2-?2-pyridyl?-1H-imidazole-4,5-dicarboxylic acid?o-H₃PIDC?as the main ligand,H₂C₂O₄ as an ancillary ligand,and rare earth metals?La?III?-Er?III??in the hydrothermal reaction with different reaction conditions under different pH values,11three-dimensional coordination polymers with optical properties or magnetic properties were created.Notably,the ligands adopt the same?₃-kN,O:kO?,O??:kO??conformation in all compounds,which brings about two types of isostructural lanthanide coordination polymers but formed two series of complexes.La?III?,Ce?III?complexes are mononuclear coordination polymers containing[Ln₂?COO?₂]secondary structural units,and the central metal is an eight-coordinate bicapped trigonal prism geometry.The Pr?III?-Er?III?complexes are binuclear coordination polymers containing[Ln₄?COO?₄]secondary structural units.Two central metals of the asymmetric unit are the eight-coordinate bicappedtrigonalprismgeometryanddodecahedronconfiguration.The photoluminescence measurement indicates that Eu?III?and Tb?III?coordination polymers show very strong reddish-orange and green emission bands with CIE chromaticity coordinates?0.612,0.325?and?0.284,0.523?and high quantum yields of 54.3%&34.7%.The magnetic properties results indicate a ferromagnetic interaction between Gd?III?magnetic centers in complex 7 and antiferromagnetic interactions in other complexes.By careful inspection of these structures,it is found that the central metals have significant influences on the resulting magnetic and luminescence properties.2?Based on 2-?3-pyridyl?-1H-imidazole-4,5-dicarboxylic acid?m-H₃PIDC?as ligands,two 2D magnetic metal complexes 12 and 13 with helical configuration were synthesized.Among them,12 is a Co coordination compound,and 13 is a copper coordination compound.The ligand H₃PIDC adopts the?₃-coordination mode in the complexes 12 and13.Each HPIDC^2-anion adopts a?₃-kN,O:kO?,O?:kN?mode connecting two Co?II?centers in bis?bidentate?and one monodentate modes in 12.In the complex 12,the carboxyl group connects Co?II?ions in a bridging mode to form a one-dimensional(-Co-HPIDC^2--Co-HPIDC^2--)chain.Ligands HPIDC^2-in 13 serve as T-shaped3-connectors,and adopt a?₃-kN,O:kN?,O?:kN?coordination mode connecting one Cu?II?atoms and one Cu?I?in bis-N,O-chelating mode and bridging another one Cu?I?in a monodentate mode.In complex 13,the Cu atoms and HPIDC^2-anions are arranged in a line to form 1D wave chains{-Cu1-Cu2-Cu3-}along the[0 0 1]direction,which are further interconnected by the HPIDC^2-ligand along b axis to forming a helix chain{-Cu2-Cu3-Cu1-}to build a 2D layer along the[0 1 1]direction.Furthermore,complexes12 and 13 featured with 2D?8²·10?and 2D?12³?₂?12?₃ network topologies,respectively.The magnetic results indicate that complex 12 shows antiferromagnetic property and complex 13 shows ferromagnetic property.3?Based on 2-?2-pyridyl?-1H-imidazole-4,5-dicarboxylic acid?o-H3PIDC?as a ligand,the transition metal Zn?II?with the d¹00 electron configuration and the main group metal Ba?II?with the S electron structures forming two optical properties coordination polymers.The resulting is quite different from structures to properties for complexes 14and 15.In complex 14,HPIDC^2-ligands link Zn?II?centers into infinite 1-D linear chains that are stabilized by hydrogen bonds and?···?stacking interactions into a 3-D supramolecular architecture.In complex 15,the central metal Ba?II?is a seven-coordinate pentagonal bipyramidal geometry.In 15,ligand H₃PIDC is partially deprotonated and links two Ba?II?centers into a?12⁶??12?₂ framework.The results of optical properties show that the complexes 14 and 15 have strong luminescence properties and the fluorescence intensity of the complex 14 is higher than complex 15.4?Based on 2-?3-pyridyl?-1H-pyrazole-benzene carboxylic acid?Hppb?as a ligand,11 different coordination polymers were synthesized by changing different metal cations or?and?anions.They play a regulatory role in the structural construction of the complexes:when only the anions were changed,five coordination polymers were synthesized.Considering the special structure of d¹00 ions,we chose it in hoped to obtain new metal compounds that exhibited photoluminescent properties.The anions of metal salts in this chapter were NO₃^–,Cl^–,Br^–,I^–,respectively.When only metal cations were changed,five isomorphic 0D binuclear structures were obtained.When both anions and cations were changed at the same time,a 0D mononuclear structure with two different kind's anions was obtained.In addition,we also studied how to increase the dimension of the complexes and enhance the optical intensity in the selection of anions.