Metal-organic Frameworks Based On Rigid Aromatic Carboxylate Ligand: Syntheses, Crystal Structures And Properties

Metal-organic frameworks (MOFs) have received great attention in the field of designand construction of the novel functional MOFs material, due to their excellent performancein gas storage, separation, catalysis, magnetism, luminescence and sensor etc. Owning tothe complicated factors such as organic ligands, metal ions, solvents and temperature thatcould have influence on the ultimate structures, the rational design and controllableprediction of the prospective networks is still a great challenge. In order to further studythe relations of structures with functions of these metal–organic frameworks, this thesisperformed research on the construction of novel metal–organic frameworks from threeacylamide-bridging multidentate carboxylate ligands with metal ions under solvothermalconditions. The three main contributions of this thesis are listed as follows.1. Three novel complexes,{[Zn2(L1)(py)(DMSO)2]·DMSO}n(1),{[Cd2(L1)(py)1.8(DMSO)1.2]·DMF·2DMSO}n(2),{[Co2(L1)(py)2(DMSO)]·0.5DMF·2DMSO}n(3), have been synthesized based onN,N’-Bis(4-carboxyphenyl)naphthalene-2,6-dicarboxamide ligand (H4L1) undersolvothermal conditions. Complex1shows a2D+2D�'3D interdigitation architecturethrough intermolecular hydrogen bonding and π···π stacking interactions between the2Ddilayer motifs. Complexes2and3are isostructural, both presenting3D porous frameworkwith (4,4)-connected crb topologies. Investigations on fluorescence and sensing propertiesof complexes2and3have also been performed. The results show that complexes2and3exhibit blue emission and high selectivity for nitroaromatic compounds.2. Six novel complexes,{[Zn2(L2)(py)(DMSO)2]·DMSO}n(4),{[Cd2(L2)1.5(H2O)2]·H2O}n(5),{[Cd3(L2)(H2L2)(H2O)5]·3H2O·DMSO·0.5DMF}n(6),{[Zn2(L2)(bpe)2]·H2O}n(7),{[Cd(L2)0.5(bpy)]·DMF}n(8),{[Cd(L2)0.5(phen)]·2H2O}n(9),were obtained based on N,N’-Bis(4-carboxyphenyl)naphthalene-1,4-dicarboxamide ligand(H4L2) and N-containing ligands (py=pyridine, bpe=1,2-bi(4-pyridyl)ethylene,bpy=2,2’-bipyridine, phen=1,10-phenanthroline) under solvothermal conditions. Complex4affords a2D planar network with1D “Z” metal chains. Complexes5,6and7possess3Dporous frameworks. Moreover, complexes8and9are similar, both showing the ladder structures. In addition, fluorescence and sensing properties of the complexes have alsobeen researched, which shows that all the complexes exhibit blue emission and complex9has high selectivity for picric acid and aniline.3. Based on N-(3,5-dicarboxyphenyl)-4-carboxy-1-naphthamide ligand (H3L3) andN-containing ligands (bpea=1,2-bi(4-pyridyl)ethane, bpp=1,3-bi(4-pyridyl)propane),two novel transition metal complexes {[Cd4(L3)2(bpea)4(H2O)2(CO2)2]·2H2O·DMF}n(10),{[Cd3(L3)2(bpp)3(H2O)2]·3H2O}n(11), and five novel rare earth metal complexes,{[Eu(L3)(H2O)2]·H2O}n(12),{[Eu(L3)(H2O)]·3H2O}n(13),[Gd(L3)(H2O)]n(14),{[Tb(L3)(H2O)]·3H2O}n(15),{[Ho(L3)(H2O)]·3H2O}n(16) were obtained undersolvothermal conditions. Due to the diversity of coordination modes and the differences ofthe metal ions, these complexes exhibit diverse structure features. Complexes10and11show different3D porous structures through the different N-containing co-ligands.Complex12has a dinuclear Eu2(CO2)2SBUs, and the dinuclear SBUs are further linkedsix neighbouring dinuclear SBUs through six different L33-ligands to form3D porousframework. Moreover, complexes13,14,15and16are isostructural, presenting3D porousarchitectures with1D metal chain. Fluorescence properties of complexes (10,11,13,15)have also been investigated. The results show that complexes10and11exhibit blueemission. Complexes13and15show a characteristic red-emission of Eu(III) and acharacteristic green-emission of Tb(III), respectively.In conclusion, sixteen complexes have been obtained based on three acylamide-bridgingmultidentate carboxylate ligands and metal ions with different methods, and characterizedby elemental analysis, FT-IR,1H-NMR, TG, PXRD and single-crystal X-ray diffraction.Furthermore, fluorescence and sensing properties of the complexes have also beeninvestigated. The complexes can not only enrich the carboxylate-complex system, but canalso be utilized as promising sensory material for such purposes as explosives monitoring.