A Series Of Coordination Polymers Constructed From The Polycarboxylate Ligands: Synthesis And Properties

Metal-organic coordination polymers were constructed from the metal nodes/cluster and the organic ligands. With rich and intriguing structures, such materials can be applied to a wide application areas, becoming a hot research field in recent years. Specifically, various synthetic routes and multiple choices of metal and organic ligands make coordination polymers possessing diverse structures which brings coordination polymers an extended research scope and wide application foreground, such as chemical sensing, the separation of chiral molecules, proton conduction, dyes adsorption and luminescence and so on.33 compounds were designed and synthesized based on the H4btca (H4btca= 1,1'-biphenyl-2,3,3',5'-tetracarboxylic acid) and H4L (H4L 5,5'-(1H-1,2,4-triazole-3,5-diyl)diisophthalic acid) ligands in this thesis and the N-donor ligands were introduced during some processes of the synthesis. The thermal stability and luminescence properties of some compounds were investigated. It is well known that the special structures of coordination polymers have profound effects on the corresponding properties. Based on the features of the structures exhibited by some compounds, the chemical sensing, crystal transformation, multi-color emission, near-infrared luminescence and dyes adsorption properties of them were investigated. The main content were shown as follows:The first chapter, a brief introduction of the post synthetic strategies of compounds and the research dynamic state of the application areas were shown. The application areas contain the chemical sensing, crystal transformation, multi-color luminescence emission and the near-infrared luminescence. The topic basis was put forward according to the introduction.The second chapter,17 compounds including 1D,2D or 3D structures were synthesized based on the H4btca/H4L (H4btca=1,1'-biphenyl-2,3,3',5'-tetracarboxylic acid, H4L= 5,5'-(1H-=1,2,4-triazole-3,5-diyl)diisophthalic acid) ligands and transition metals. During some part of the self-assembing process, the auxiliary ligands were introduced and play important roles. The effort was made to discuss the effects of the auxiliary ligands and solvent polarity on the formation and final structures of compounds. Some pairs of the compounds, such as 1 and 3,5 and 6,8 and 9, were synthesized under the similar experimental conditions except the introducing of different auxiliary ligands between each other of the pair. Different auxiliary ligands possess the different geometries and different number and position of the coordinate atoms. The comparison of structures were made for each pair and the conclusion was got that the auxiliary ligands together with the H4btca ligands possessing the different coordination modes both result in the different structures. In terms of compound 5 and 6,5 shows a 2-D structure while 6 exhibits the 3-D structure due to the introducing of PyBIm ligand in 5 and the triangular Htpim ligand in 6. Thus the dimensions of the compounds could be controlled by the auxiliary ligands to some extent. The mixed solvent with different polarity was used during the synthesis of compound 17. After adjusting the solvent ratio of DMF:C2H5OH:H2O, the phenomenon occurs that compound 17 can be got from the solvent with the higher polarity. Such discovery enriches the experiences of the design and synthesis of the compounds.The third chapter, seven 2-D lanthanide metal-organic frameworks containing the uncoordinated -COOH were constructed by the H4btca ligands and lanthanide metal ions with the formular [La(Hbtca)(H2O)3]n (18), {[Tb(Hbtca)(H2O)4]·H2O}n (19) and{[Ln(Hbtca)(H2O)2]·H2O}n (Ln= Tb (20), Yb (21), Eu (22), Y (23), Er (24)). Compounds 20-24 were isomorphous. Compound 19 shows the narrow and green luminescence emission spectra of Tb3+ and the variation of the luminescence intensity could act as one sensing signal.19 exhibits selective sensing properties of nitroaromatic compounds via the luminescence quenching effect. 20, with the uncoordinated-COOH in the pores, emits the green characteristic luminescence emission spectra of Tb3+. Owing to the potential coordination ability towards the foreign metal ions of -COOH, compound 20 can selectively recognize Fe3+ in the aqueous environment via the luminescence quenching effect and without the interference from other co-existed metal ions.The fourth chapter, the reversible single crystal to single crystal transformation was realized for compound 19 at room temperature. After immersing 19 in the aqueous solution of Cu(NO3)2 at ambient temperature, a totally different structure, compound 25 with the formular{[Cu2.5(?3-O)(OH)(H2O)3]·7H2O}n, was formed. After being immersed in the aqueous solution of Tb(NO3)3,25 can recover back to 19. This is the first example of reversible crystal transformation which occurs between the different valences of metal ions and accompanied by the change of metal coordination environment.The fifth chapter, eight isostructural Ln-MOFs, namely, [Ln(Hbtca) · x(H2O)]n(Ln= Nd(26), Sm(27), Eu(28), Gd(29), Tb(30), Ho (31), Er(32), Yb (33)), with the uncoordinated-COOH in the pores, were constructed based on the H4btca ligands. The average bond lengths of Ln-O obtained from the single crystal data were analysed. When the radius of Ln3+ decrease, the average bond length of Ln-O decrease. Such phenomenon indicates there exist the lanthanide contraction effect. This series of Ln-MOFs realize the multiple applications shown as follows: Compound 26 has the near-infrared luminescence. Owing to the red characteristic luminescence of Eu3+ exhibited by compound 28 and the green characteristic luminescence of Tb3+ exhibited by compound 30, the co-doped materials with the luminescence emission color varing from red to green were designed and synthesized. These co-doped materials have the similar experimental conitions as compound 28 except a mixtures of Eu(NO3)3·6H2O and Tb(NO3)3·6H2O instead of pure Eu(NO3)3·6H2O. Such series of co-doped materials (compound 34-38) shows the multi-color luminescence emission. Compound 30 can selectively adsorb the dyes of congo red. With the uncoordinated -COOH in the pores, compound 30 have the hydrogen-bond interaction with the dyes of the congo red.