Design And Synthesis In/M-MOFs And Their Selective Gas Adsorption And Fluorescence Detection Properties

Metal-Organic Frameworks?MOFs?have received wide attentions due to their enormous potential applications such as gas selective adsorption and separation,optical and chemical sensing,etc.Their unique structures can be constructed by selecting suitable metals and ligands.Despite their many advantages,the applications of MOF materials are limited due to poor stability under severe conditions.Therefore,it is highly demanded to design and fabricate MOF materials with higher stability and excellent performance.Heterometallic MOF materials have certain potential in improving the performance and stability of the frameworks.They not only combine the physicochemical properties of two metals,but also provide the chances to obtain novel topologies.In this paper,based on the hard and soft acid-base theory,CBDA[5,5-(carbonylbis?azanediyl?-diisophthalic]acid was chosen as the organic ligand to successfully construct three unique heterometallic MOF materials.And their structures and related properties are characterized.The main research contents are as follows.1.Synthesis and performance studies of stable In/Tb-CBDA and In/Eu-CBDA:Under solvothermal conditions,two heterometallic MOFs In/Tb-CBDA and In/Eu-CBDA have been successfully constructed by CBDA ligand and bimetallic center?terbium nitrate/europium nitrate and indium nitrate?.By Single-crystal X-ray diffraction analysis,the two compounds are isostructural.These structures possesses?4,4,6?-connected network linked by tetra-nuclear[In₄O₂?COO?₄]cluster,tri-nuclear[M3O?COO?6]cluster?M=Tb,Eu?and ligand CBDA,which is a novel topology.In the structure,the unique tetra-nuclear[In4O2?COO?4]cluster chelated by two?3-O centres are linked by four carboxylate groups from four ligands,a tri-nuclear[M₃O?COO?₆]?M=Tb,Eu?cluster chelated by two?₃-O centres are linked by six carboxylate groups from six ligands.In addition,they have good porosity and high acid-base stability.We systematically studied the performance of In/Tb-CBDA and In/Eu-CBDA for the adsorption and separation of CO₂,CH₄,C₂H₆ and C₃H₈ and the detection of dichromate ions as well as nitroaromatic compounds.The results show that In/Tb-CBDA has excellent selectivity for C₃H₈/CH₄ and good detection ability for dichromate ions.2.Synthesis and gas adsorption/separation studies of In/Cu-CBDA:By using same CBDA as organic ligand,a novel 3D skeleton network was assembled under the condition of mixed solvothermal by introducing copper nitrate to form bimetallic center with indium nitrate,named as In/Cu-CBDA.The structure contains In?COO?₄clusters and[Cu₂?COO?₄]clusters,which are connected by ligand CBDA to form a three-dimensional network with nbo-topology.In the structure,it exists two kinds of cages?Cage A and Cage B?with different sizes and shapes.The cages interconnected alternately to extend a one-dimensional MOP chain.Interestingly,the structure exhibits two types of helical chains with opposite helical directions?left-and right-handed helical chains?,which are less common in the reported literature.In addition,In/Cu-CBDA displays good stability and high gas adsorption and separation properties.