Synthesis, Crystal Structures And Properties Of Porous Coordination Polymers With N-containing Heterocyclic Ligands And Carboxylate Ligands

This work focuses on the novel metal organic frameworks (MOFs) based on small simple N-containing heterocyclic ligands and benzene-polycarboxylate ligands with high symmetry (1,2,4-triazolate, benzene-1,3,5-tricarboxylate and benzene-1,2,4,5-tetracarboxylate). The relationship between the structures and their relevant properties of those complexes has been deeply discussed and also demonstrated. The thesis could be divided into four chapters. In Chapter 1, a brief introduction was given to the development of coordination chemistry and application of coordination complexes. Meanwhile, the development of coordination chemistry involved in triazolate and benzene-polycarboxylate ligands were emphasized. Finally the intention and significance of this study were elucidated.In Chapter 2, hydrothermal reactions of cadmium chloride and 1,2,4-triazole (Htrz) in different solvent medium have successfully synthesized three ternary Cd(II)/trz/Cl– complexes, [Cd(trz)Cl]·H₂O (1·H₂O), [Cd₄(trz)₅Cl₃(H₂O)]·(THF)_1.25·(H₂O)_2.5 (2·1.25THF·2.5H₂O), and [Cd₄(trz)₆Cl₂(H₂O)0.5]·(H₂O)_3.5 (3·3.5H₂O). All of these three coordination polymers behave three-dimensional (3-D) structural feature, which are constructed by distinct substructures including clusters, chains, rings and even 3-D frameworks. In all cases, 1,2,4-triazolate adoptsμ₁,2,4 bridging mode and chloride ions displayμ₂,μ₃,μ₄ bridging mode respectively which makes the structural diversity in the assembling system, for example,μ₄-Cl and cadmium triazolate build up an unprecedented tetranuclear cluster [Cd₄(trz)₈Cl]^– in 2. All of the materials exhibit intense blue fluorescent emission and high thermal stability wherein 1 present interesting guest-dependent photoluminescent property.The chapter 3 systematically investigated the hydrothermal reactions of benzene- polycarboxylic ligands and triazole with Cu(II) and Cd(II) salts under different conditions, thereby, obtaining seven new complexes, [Cu₁₈^IICu₂·(trz)₁₂(btc)₈·Cl] (CH₃CN)₈·nH₂O (4), [Cu₃^II (btc)₂·Cl_n·(OH)_n ]·[Cu^I(CH₃CN)]_n·nH₂O (5), Cu₂^II(Htrz)(btc) (μ₃-OH) (6), Cu₂^IICu^I (trz)₃(Hbtc) (7), Cu4(trz)2(H₂btec)(OH)2·H₂O (8), [Cd(AmtrzH) (Hbtc)]·H₂O (9), [Cd(Hbtc)·H₂O]·Him (10), with the emphasis on the template effects of guest during the synthesis. Counter ions, solvents, the ratio of reactants and pH value have different effects on the structures of the complexes. Additionally, topology analysis have been carried out and examined. The alternate arrangement of the 1,2,4-triazole and benzene-1,3,5-tricarboxylate in MOFs of 4 and 7 is an interesting phenomenon which is the first case in the construction of MOFs.In chapter 4, a briefly conclusion on this work and an outlook have been viewed.