The Design And Synthesis Of Metal–Organic Polyhedra Based On Polyoxotungstates And Polyoxovanadates

Polyoxometalates?POMs?are common basic building units in multifunctional materials and have attracted great interests because of their versatile structures and excellent properties.In recent years,it has become a hot topic in inorganic chemistry to connect POMs with organic ligands,construct metal-organic polyhedra?MOPs?and study their catalytic,adsorption and magnetic properties.This thesis mainly focuses on the design and synthesis of novel MOPs based on polyoxotungstates?POTs?and polyoxovanadates?POVs?.In this thesis,four starting materials were prepared,among which the inorganic raw materials were Na₁₀[A-?-SiW₉O₃₄]·18H₂O?A-?-SiW₉?and TBA₄[?-H₂SiW₁₀O₃₆Pd₂?OAc?₂](TBA-y-SiW₁₀-Pd₂),organic ligands were 4,4',4"-?1,3,5-triazine-2,4,6-triyl?tribenzoic acid?H₃TATB?and 4,4',4"-??1,3,5-triazine-2,4,6-triyl?tris?azanediyl??tribenzoic acid?H3TATAB?.The meterials were confirmed to be target products by IR and ¹H-NMR.According to the structural characteristics of POTs,a new polyoxotungstate-based metal-organic complex was designed and synthesized.It was prepared by a reaction of succinic acid with TBA-?-SiW₁₀-Pd₂ in organic solvents.The molecular formula is[?n-C₄H₉?₄N]₁₂[(?-SiW₁₀O₃₆Pd₂)?O₂C?CH₂?₂CO₂?]2?1?.The product was characterized by single-crystal X-ray diffraction,IR,¹H-NMR and TG.Compound 1 crystallizes in the tetragonal system with the space group P4/n c c,and it is a linear molecule composed of two {?-SiW₁₀O₃₆Pd₂} and two succinic acids.Compound 1 successfully incorporates organic ligands into POTs,which validated our design strategy in connecting POTs and flexible organic ligands,and provided a feasible experimental route to MOPs based on POTs.According to the structural characteristics of POVs,two polyoxovanadate-based MOPs were designed and synthesized.They were prepared with tridentate carboxylate ligands and VCl₃ under solvothermal conditions.Their molecular formulas are?NH₂Me₂?₁₂[?V₅O₉Cl?₆(C₂₄H₁₂O₆N₃)₈]·solvent?2?and?NH₂Me₂?₁₂[?V₅O₉Cl?6-(C₂₄H₁₅O₆N₆)8]?3?.The products were characterized by single-crystal and powder X-ray diffraction,IR,1H-NMR and TG.Both are octahedral structures composed of six{V₅O₉Cl} and eight tricarboxylic acids;the former is prepared with a new synthetic method and the latter is a novel MOP.Compound 2 crystallizes in the cubic system and Fm3m space group,and it has an inner cavity diameter of approximately 2.2 nm.Compound 3 crystallizes in the cubic system with the space group F432,and it has an inner cavity diameter of approximately 2.4 nm.The magnetic property of compound 2 showed that there was ferromagnetic behavior,which was rare in the mixed valence vanadium clusters.In this thesis,our objective is to design and prepare targeted MOPs with directional combination of organic polycarboxylates with POTs/POVs.The syntheses of MOPs based on POVs used reported hydrothermal methods and could be easily carried out with a variety of bridging ligands.On the other hand,with POTs,the traditional bench synthesis has to be adopted.While we successfully introduced a new flexible carboxylate linker,further work is still needed to find proper conditions where more rigid linkers may be incorporated.