Synthesis,Characterization Of Metal-organic Frameworks Based On Rigid Imidazole Ligands

Metal-organic frameworks?MOFs?,which are built up of organic ligands and metal ions or clusters,have been attracted tremendous interests because their high porosity,enormously high surface areas and tunable structure cause various applications in gas storage/separation,catalysis,magnetism,drug delivery,sensing and so on.In addition,MOFs with fluorescent property have been also concerned by scientists and applied in luminescence detection and photocatalysis.The tetraphenylethene?TPE?consisting of four benzene rings and one olefinic bond is a typical fluorescent activating materials with aggregation induced emission characteristics owing to good fluorescent property.Based on tetraphenylethene,we synthesized a rigid quadridentate imidazoles ligand tetra?4-imidazoylphenyl?ethylene?TIPE??L?.Five novel MOFs {[Cd₄?L?₂?OBBA?₄]·8H₂O}n?1?,{[Co₄?L?₂?BPDC?₄]·5MeCN·16H₂O}n?2?,{[Cu₄?L?3·5Cl}n?3?,{[Cd₄?L?₂]·2H₂O}n?4?and {[Co₄?L?₂?BPDC?₄]·2H₂O}n?5?have been synthesized by hydrothermal synthesis and post-synthesized method,and characterized by PXRD,FTIR,single-crystal X-ray diffraction and elemental analysis.Also,potential applications have been investigated by adsorption,luminescence and catalysis.Crystallographic analysis indicates that the structure of complex 1 is the 4-fold interpenetrating form,which exhibits a?4,4?-connected 4-c afw net with a {{3.75}{3.7.7.7.7?2?.7?2?} topology.Considering the Co²⁺cations as 5-connected nodes,while the L ligand as 4-connected nodes links adjacent Co²⁺ cations,complex 2 shows a 3D?3D 4?2+2?-fold interpenetrating?4,5?-connected4,4-c 4T67 net with the point symbol of {{4.64.8}2{42.62.82}.Whereas,compound 3with an rarely prefect tetrahedron [Cu₄Cl]³⁺ cluster is a uninodal?4,4?-connected sqc6 net,which the point symbol of topology is the {66},{6?2?.6?2?.6?2?.6?2?.6?2?.6?2?}.Complex 4 is a chain like a bowknot and multiple chains form a 2D structure.Complex5 shows a 3D interpenetrating form with two types of channels which the sizes are23.2602?13?× 15.974?12??2 and 24.6324?15?× 14.5478?12??2,respectively.The thermogravimetric analysis?TGA?shows that four complexes 1-4 possess a quite thermal stability which can stable up to 300 ?.The solid state photoluminescence?PL?spectra study certified that compound 1,3 and 4 show intense photoluminescent peak and complex 1 have good sensitivity toward methamphetamine and nitroaromatic explosives by photoluminescence quenching.Moreover,complexes 4 shows good catalytic activity for 1,3-dipolar cyclization reactions and the yield can reach 90 % when the temperature is 60 ? and the reaction time is 3 h.Porphyrin and metalporphyrin derivatives were widely used in the construction of MOFs by scientific research workers,due to their unique physical,chemical,and electronic properties and their functions on energy and electron transfers,light harvesting and catalysis.Thus,a MOFs [Cd₃L₃Cl₃O₂]·solvent?6?based on 5,10,15,20-tetra?4-imidazolyl?porphyrin was synthesized by hydrothermal synthesis,and the single crystal X-ray analysis revealed that [Cd₃L₃Cl₃O₂]·solvent?6?crystallizes in the triclinic p₁ space group.