Syntheses,Characterization And Properties Of New Metal-organic Frameworks Based On Tripodal Ligands

In recent decades,metal-organic framework materials?MOFs?have become one of the current research focuses with their high porosity and specific surface area,rich and varied topology,fine physical and chemical properties such as adjustability and tailorability,which were widely used in gas storage,catalysis,separation purification,drug delivery,sensors and other fields.In this paper,based on the mixed-ligand strategy,a total of 10 new structures of MOFs were successfully constructed through two kinds of designed rigid tripodal ligands with the second carboxylic acid ligands and metal ions.Their structures and physical properties have been evaluated.The detailed studies are as follows:1.Syntheses,characterization and properties of five interpenetrating MOFs based on tripodal ligand tris[4-?1H-imidazol-1-yl?phenyl]phosphine oxide?tipo?.Five metal-organic frameworks with the combination of novel tripodal ligand tris[4-?1H-imidazol-1-yl?phenyl]phosphine oxide?tipo?and different polycarboxylates,namely[Zn₂?bpdc?₂?tipo??H₂O?]�5H₂O?1?,[Cd?tipo?₂][Cd₂?bdc?₃]�4H₂O?2?,[Cd₂?ndc?₂?tipo?₂]�4H₂O?3?,[Cd₂?bpedc?₂?tipo?₂]�15H₂O?4?and[Cd₂?hfdc?₂?tipo?₂]�10H₂O?5?,have been synthesized and structurally characterized.Compound 1 featured a 2D?3D parallel polycatenation of 3,3,4-connected net with the unusual 4 degree of catenation and 2 index of separation.Compound 2 showed an unprecedented polycatenation of charged networks 2D kgd and 3D pcu constructed by different organic ligands.Compound 3 exhibited a combination of 2D?3D parallel polycatenation of sql net and polythreading.Compound 4 featured a 4-fold interpenetration of 3,5-connected 3,5T1 net.Compound 5 displayed an unusual 2-fold interpenetration of sdd net.The luminescent properties of 1-5 in the solid state have been investigated.2.Synthesis and properties of two self-catenated MOFs based on tris[4-?1H-imidazol-1-yl?phenyl]phosphine oxide?tipo?Two novel self-penetrating metal-organic frameworks,namely [Cd₃?bdc??HCOO?₂?tipo?₂?H₂O?₂]�2NO₃�6DMF?6?and[Zn₈?OH?₄?bpdc?₆?tipo?₄]�16DMF?7?have been successfully synthesized.Compound 6exhibited a cationic 4,6-connected self-catenated framework with large 1D channels.Compound 7 featured a 3,4-connected self-catenated framework with potential O-donor located on the surface of the channels.Compound 6 showed a high adsorption for dichromate.Post synthetic modification of 7 by lanthanide ions(Eu³⁺and Tb³⁺)afforded fluorescent materials.3.Syntheses,characterization and properties of three entangled MOFs based on tripodal ligand tris[4-?2'-methylimidazol-yl?phenyl]phosphine oxide?tmpo?Three new entangled metal-organic frameworks,namely[Zn₂?cdc??tmpo?₂]�2NO₃�5DMF?8?,[Cd₃?2,6-ndc?₃?tmpo?₂]�8H₂O�4DMF?9?and[Cd₂?bpedc??tmpo?₂]�2NO₃�4H₂O�2DMF?10?have been synthesized and structurally characterized.Compound 8 was an unusual self-catenated cationic metal-organic framework.Compound 9 featured an unusual 3,4-c self-catenated framework.Compound 10 presented an unprecedented 4,5-c self-catenated framework.Furthermore,the photochemical properties of these three compounds were investigated in detail.Because of the cationic framework and good water-stability of 8,this compound showed efficiently selective adsorption of anionic dyes from water.Compound 10 could be served as a good fluorescent sensor for 4-NP and 2,4-DNP detection,with the detection limits of 1.4�10^-44 M for 4-NP and 5�10^-55 M for 2,4-DNP.