Design,Synthesis And Property Study Of Novel Polyoxovanadates-Based Metal-Organic Polyhedra

Metal-organic polyhedra?MOPs?are an emerging class of porous supramolecular materials after metal-organic frameworks?MOFs?and zeolites.They are a class of discrete metal-organic molecular entities formed by the edge-sharing and vertice-sharing of molecular polygons.MOPs have high outer and inner specific surface areas and nano-scale cage-like structure,flexible geometric topology,can be applied in different fields,such as catalysis,gas separation,drug delivery,molecular sensing and so on,they can also be used as molecular building blocks to further build the extended network.Polyoxovanadates?POVs?are an important branch of polyoxometalates.Due to their coordination flexibility and structural diversity,they are more easily used as secondary building units?SBUs?to construct isolated molecular entities.In this thesis,twelve polyoxovanadate-based metal-organic polyhedra are successfully designed and synthesized by selecting different vanadates to react with bidentate,tridentate,and tetradentate carboxylate ligands.The metal-organic polyhedra with specific geometric configurations are obtained by modifing temperatures and different solvent ratios under solvothermal conditions.Due to their inherent properties,the structures have been studied for ion exchange and magnetic properties.1.Inspired by Reticular chemistry theory,we selected the trivalent polyoxovanadate clusters and linear bidentate carboxylate ligand H₂EDB as starting reactants.Under solvothermal conditions,two true supramolecular isomers based on tetrahedra were synthesized.The reversible structural transformation between two supramolecular isomers can be achieved by temperature induction in a solvent medium.Since compound 2 has a 5.4nm channel,the biomolecule vitamin B₁₂2 can be adsorbed into the crystal lattice by ion exchange mechanism.[Me₂NH₂]₅[V₆O₆?OCH₃?₉?SO₄?₄]?1?{[V₆O₆?OCH₃?₉?SO₄?]₄?edb?₆}^8-?2?{[V₆O₆?OCH₃?₉?SO₄?]₄?edb?₆}^8-?3?EDB=4,4'-?ethyne-1,2-diyl?dibenzoic acid2.Under solvothermal conditions,we use trivalent polyoxovanadate clusters and faced tridentate carboxylate ligand H₃TATB to assemble two novel polyoxovanadate-based metal-organic polyhedra.We have investigated the absorption ability of compound 4 toward dye molecules of different charge and size,only cationic dyes can be adsorbed into the crystal lattice through ion exchange except neutral and anionic dyes.[NH₂Me₂]₄{[V₆O₆?OCH₃?₉?VO₄?]₄?TATB?₄}·?MeOH?₂₄?4?[NH₂Me₂]₈{[V₆O₆?OCH₃?₉?SO₄?]₄?TATB?₄}·?MeOH?₈?5? TATB=1,3,5-triamino-2,4,6-trinitrobenzene3.Under the guidance of the face-directed assembly,we selected trivalent polyoxovanadate clusters and tetradentate carboxylate ligands to assemble five novel polyoxovanadate-based metal-organic cubes.Interestingly,compound 8 of this series is investigated as a molecular receptacle,which can adsorb cationic dye and in situ targeted capture pyrene molecule to generate host-guest supramolecular composite–compound 11.?NH₂Me₂?₁₆[?V₆O₆?OCH₃?₉?SO₄??₈?BPTC?₆]?6??NH₂Me₂?₁₆[?V₆O₆?OCH₃?₉?SO₄??₈?ABTC?₆]?7??NH₂Me₂?₁₈[V₆O₆?OCH₃?₉?SO₄?)₈?EBTC?₆]·?SO₄??8??NH₂Me₂?₂₂[?V₆O₆?OCH₃?₉?SO₄??₈?TPTC?₆]·?SO₄?₃?9??NH₂Me₂?₂₂[?V₆O₆?OCH₃?₉?SO₄??₈?ADIP?₆]·?SO₄?₃?10??NH₂Me₂?₁₈[V₆O₆?OCH₃?₉?SO₄?)₈?EBTC?₆]·?SO₄?·?pyrene?₂?11? BPTC=1,1'-biphenyl-3,3',5,5'-tetracarboxylic acid ABTC=azobenzene-3,3',5,5'-tetracarboxylic acid EBTC=1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic acid TPTC=terphenyl-3,3',5,5'-tetracarboxylic acid ADIP=5,5'-?anthracene-9,10-diyl?diisophthalic acid4.Based on the previous works of our group,under similar solvothermal conditions,we selected VOSO₄,NbCl₅,and H₃BTC as starting reactants to synthesize a unprecedented?3,4,5?-coordinated trinodal polyoxovanadate?POV?-based metal-organic polyhedron with undiscovered“Near-miss Johnson Solid”geometry,in which the polyoxovanadate cluster[NbV₅?SO₄?]acts as a 5-connected vertice,[V₅O₉Cl]acts as a 4-connected vertice,and the organic ligand H₃BTC acts as 3-connected vertice.Magnetic studies have shown that the structure is ferromagnetic.[NH₂Me₂]₃₀{[NbV₅O₆?m₃-O?₅?SO₄?]₄?V₅O₉Cl?₄?BTC?₁₂]}·?SO₄?₃?12?BTC=benzene-1,3,5-tricarboxylic acid...