Synthesis, Structure And Property Study Of Coordination Polymers Based On Azoledicarboxylate Ligand

Coordination Polymers （CPs）, as a novel functional material, arouse extensive attentionrecently. Their permanent porosity, high surface areas, fine-tunable pore structures, andadjustable chemical functionalities make them possessing potential applications in gas storage,catalysis, gas adsorption and separation, luminescence, and magnetism. As diverse organicligands were explored, and postsynthesis or modification for MOFs materials, the chemicaland physical properties would be improved and expanded the application scope. Recently, italso possessed the applications in drug release and sensor in biology. Therefore, assemblingMOFs with unique structures and tailor-making properties by rational design have a greatsignificance in developing novel materials.Herein, we utilize two organic ligands,1,2,3-triazole-4,5-dicarboxylic acid （H₃tzdc） and1,2,5-thiadiazole-3,4-dicarboxylic acid （H₂tdc） coordinated with different types of metalcenters （indium, lanthanide, and transition metal） to construct novel MOFs materials undersolvothermal conditions.19compounds were synthesized by changing the solvent polarity,pH value, temperature, and inducing different organic amine. The properties such as gasadsorption, luminescence for some compounds were investigated. We get the following threeaspects results:1. Four indium-organic frameworks1-4were solvothermally synthesized based on H₃tzdcand H₂tdc ligands, respectively, by inducing three types of organic amine. In compound1,four1,2-DACH molecules serving as terminal ligands in combination with four In³⁺ions andfour tzdc_3-ligands generate a metal-organic square （MOS）, and MOS was linked via K+toform a3D framework. Each MOS connected each other via16hydrogen bonds to produce azeolite-like rho topology. Compounds2and3have a similar reaction conditions with H₃tzdcligand and TMDP molecules. In compound2, three tzdc_3-ligands and three formic acidmolecules, as well as six In³⁺composed a hexanuclear cluster, and the ligand linked to thehexanuclear cluster to form a3D framework with a22A hexagonal-shaped nanopores. The ^framework exhibited a novel （4,6）-connected net. In compound3, twelve tzdc_3-ligandscoordinated with eight In³⁺to generate a metal-organic cubic （MOC）, and each MOCconnected each other by hydrogen bonds to form a3D supramolecular structure with four-foldInterpenetration. Each single fold structure possessing a pcu topology has a channel withdiameter of27.9×13.8A. Compound4based on H₂tdc ligand was obtained by inducingorganic amine Phen. In compound4, each MOS, constructed by two In³⁺, two tdc^2-ligandsand four Phen molecules, as the secondary building unit, connected each other via hydrogenbonds to form a2D layer structure. Compounds1-4with high thermal stability werecharacterized and formulated by elemental analysis, thermogravimetric analysis andsingle-crystal X-ray diffraction. Compounds1and2exhibited gas adsorption properties, andcompounds2and3displayed luminescent properties.2. Twelve novel three-dimensional （3D） lanthanide metal-organic frameworks5-16withformula [LnK（C₄N₂O₄S）2（H₂O）₂]（H₂O）_0.5（Ln=La （5）, Ce （6）, Pr （7）, Nd （8）, Sm （9）, Eu （10）,Gd （11）, Tb （12））,[LnK（C₄N₂O₄S）（C₄O₄）（H₂O）₂]（H₂O）_0.5（Ln=La （13）, Ce （14））, and[Ln₂（C₄N₂O₄S）₃（H₂O）]（H₂O）（Ln=La （15）, Ce （16））, were solvothermally synthesized by2,1,3-thiadiazole-4,5-dicarboxylate （H₂tdc） ligand with corresponding lanthanide nitrate.Three types of the structure from nonporous to microporous frameworks were exhibited withthe changing of solvent polarity, the ratio of ligand and metal center, and inducing the secondliner ligand fumaric acid. Compounds5-12with the isostructure （structure I） contain a1Dzigzag chain along the b axis, which connected by K⁺and pillared water molecules to form3D frameworks with moc topology. Compounds13and14are isomorphous coordinationpolymers （structure II） possessing a similar zigzag chain, which linked via the coligandfumaric acid to construct3D frameworks with dia topology, while compounds15-16（structure III） are isomorphous coordination polymers. They possess a1D right-left helicalchains along the b axis, and the right-left helical chains alternatively linked to form a3Dframework with a new （3,4,5）-connected topology. As the antenna effect of the H₂tdc ligand,the luminescent property shows that compounds9,10,12displays intense orange, red andgreen luminescence and exhibits the typical Sm³⁺, Eu³⁺and Tb³⁺ion emission, respectively.3. Three transition metal-organic frameworks17-19were solvothermally synthesized byH₃tzdc ligand. Compound17based on Cd²⁺, contained a tetranuclear cadmium cluster, and the cluster was connected via ligand to form a3D framework with bnn topology. Bothcompounds18and19were obtained by Cu²⁺. In compound18, four Cu²⁺and four ligandscomposed a unique metalloporphyrin-like plane, resulting in a3D framework with ptotopology. In compound19, twelve Cu²⁺and six tzdc^2-ligands form a Kagomé-like plane,leading to a2D layer, thus4,4’-bpy was induced as the pillers to hold the layers to generatethe3D framework, and the structure possessed a new topology with the （3,4）-connected net.Compounds17-19were characterized and formulated by elemental analysis,thermogravimetric analysis and single-crystal X-ray diffraction. Compound17, with highhydrothermal stability and open Cd sites, has been found to exhibit luminescent responsetoward different organic solvents, and it also displayed gas adsorption property.In summary, we utilized secondary building unit approach to synthesized19coordinationpolymers in solvothermal conditions. The results described here illustrate the influence of thevarious coordination modes to the unique structures, and the experimental data enriched thestructure and topology information of MOFs materials. The gas adsorption properties andluminescent properties provide value for the continuous development of functional MOFs.