| In recent decades,metal–organic frameworks?MOFs?have attracted much research interests for their diverse structures and potential applications in the realm of gas storage and separation,catalysis,photoluminescence,and chemical sensing.Nitroaromatic explosives detection has aroused much attention for the increasing concern about homeland security,environmental protection,and humanitarian implications in recent years.Fluorescence-based detection approach shows superiority for its remarkable sensitivity,simplicity,short response time,and ease of operation compared with other methods of explosive detection.Increasing attention has been paid to the design and synthesis of luminescent MOFs for the sensing and detection of explosives.Their tunable cavities,functionalized pore surfaces,ordered nature and large surface areas allow more contact of MOF surface with explosives.The aim of this thesis is to synthesize novel porous MOFs which may exhibit well fluorescent property.Based on these porous fluorescent MOFs,the property of these compounds detecting explosives is explored.In this thesis,the 1,3,5-tris?p-imidazolylphenyl?benzene?Tipb?act as main ligand to react with different carboxylate ligands in the presence of cadmium salts.By trial and error,we successfully synthesized five novel porous MOFs with interpenetration structure.Their structures were characterized by elemental analyses,ICP analyses,IR spectra,single-crystal X-ray diffraction analyses and X-ray powder diffraction?PXRD?.Besides,the thermal stabilities?TG?,fluorescent properties and sorption properties were also investigated.Five novel porous MOFs with interpenetration structures have been synthesized by self-assembly of 1,3,5-tris?p-imidazolylphenyl?benzene,benzene-1,3,5-tricarboxylic acid,thiophene-2,5-dicarboxylicacid,fdc=furan-2,5-dicarboxylicacid,2,6-Naphthalenedicarboxylic acid and cadmium salt,that are,[Cd2?Tipb?2?btc?Cl]·Gx?1?[Cd?Tipb??tdc?]·Gx?2?[Cd?Tipb??fdc?]·Gx?3?[Cd5?Tipb?4?btc?2Cl2?DMF?2?H2O?5]·Cl2·Gx?4?[Cd?Tipb??naph?]·Gx?5?Compound 1 and 4 are close to being isostructural,they all exhibit twofold interpenetrating3,4,5-connectednetworkwithpointsymbolof(42.6.82.10)(42.6.84.103)(42.6)2?83?.After interpenetrating,solvent accessible void of compound1 is still 39.1%of the crystal volume.Compound 2 and 3 are isostructural,they all show twofold interpenetrating?3,5?-connected with point symbol of?63??66.84?.The solvent accessible void of compound 3 and 4 are 33.8%and 33.4%respectively after interpenetrating.Compound 5 is also a two-fold interpenetrating?3,5?-connected network.But the effective free volume of compound 5 is 64.8%of the crystal volume,which is the biggest one in these compounds.Four of these MOFs exhibit strong fluorescent emission upon excitation at room temperature.Due to the presence of?-electron-rich N-donor ligand,the sensing sensitivities of compounds 1-4 towards electron deficient nitroaromatic explosives such as2,4,6-trinitrophenol?TNP?,2,4-dinitrotoluene?2,4-DNT?,1,3-dinitrobenzene?1,3-DNB?,nitrobenzene?NB?have been studied by fluorescence quenching experiments.The results indicate that compounds 1-3 are highly sensitive to TNP owing to the electron and energy transfer between MOFs and TNP.Besides,compound 1 shows selectivity to TNP when mix the TNP with others nitroaromatic explosives.Furthermore,these compounds remain stable after quenching and exhibit fine recyclability.Besides,the adsorption properties of 1-3 have also been investigated. |
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