| Metal organic framework materials(MOFs)have a lot of potencial applications in absorption,catalysis and detection,due to their porous structures.Ionothermal reactions have attracted much attention in the synthesis of MOFs materials,with the fact that with ionic liquids(ILs)as reaction media,ionothermal synthesis shows advantages of environment-friendly,safety,and significantly different reaction environment from hydro(solvo)thermal one.Our work used low eutectic mixed solvents(DESs),one important member of ILs,as reaction media to obtain tranditional metal MOFs,and to control the cavity structures and properties of MOFs through the components of DESs.1.In this part,four types of DESs,choline chloride/urea,choline chloride/acrylamide,choline chloride/ethylene glycol,choline chloride/1,3-dimethyl urea,as reaction media,Ni(NO3)2· 6H2O,Co(NO3)2·6H2O,Zn(NO3)2·6H2O,and Cu(NO3)2·6H2O act as metal sources to react with 1,3,5-benzenetricarboxylic acid(H3BTC)ligand to give seven M-BTC MOFs:OD macrocyclic[M2(HBTC)2(N2H4C0)2]·7H20(M = Ni(Nil),Co(Col),N2H4CO = urea),1D[Zn4(HBTC)4(H20)8(H2N2C0)2](Znl),2D[Cu2(BTC)Cl]·H20(Cul),[Ni3(BTC)3]· 8H20(Ni2),[Ni2(BTC)Cl][(CH3)2N2CO]2(Ni3,(CH3)2N2CO =1,3-dimethyl urea),and 3D[Cu3(BTC)2(H2O)3](Cu2).As DESs = choline chloride/urea,the products are isomorphism Nil and Col;DESs = choline chloride/acrylamide or choline chloride/ethylene glycol,te similar ionotrhermal reactions gave out the same product Ni2;as = choline chloride/acrylamide,or choline chloride/ethylene glycol,or choline chloride/1,3-dimethyl urea,the reactions gave out the same product Cu2.All compounds are characterized by single crystal X-ray diffraction to resolve the single crystal structures,powder X-ray diffraction to determine the phase purities of the bulk samples,thermogravimetric analysis to determine the thermal stabilities,FT-IR and fluorescence for the spectroscopic properties.The structure analysis indicates that most of the compounds do not contain any components of DESs as guest molecules,but as secondary ligands with urea or 1,3-dimethyl urea.It is different from those obtained in halide 1-methyl-3-alkyl-imizole ILs which always contain alkyl imizole templates as guest molecules.It suggests the regulation on the structure by ILs.2.The structure transformation.The OD macrocyclic Nil can transferred into layered MOF Cul through the ionothermal reactions with Cu2+;similarly,2D layered Ni2 can transferred into 3D architecuture Cu2 through the ionothermal reactions with Cu2+ or ion exchange with Cu2;2D layered Ni3 can changed into 3D architecuture Cu2 through ion exchange with Cu2+.The ion exchange experiments show the cation species,concentration,soaking time and temperature play important role on the opening degree of cavities in Nil-Ni3.In the structure transformation of Nil,divalent metals show better substitution ability to Ni2+ than mono-or trivalent metals.Cu2+ exhibits the best substitution,ability to Ni2+.N2 absorption confirms that the N2 absorbance of the intermediate products increase with the Cu2+ concentration,soaking time and temperature,showing the replacement rate of Cu2+ to Ni2+ increase.The mechanism may be related with which Cu2+ links to uncoordinated carboxylate and relase a part of the cavity.The soaked products show large CO2 asorption,which means the chemical asorption occurs between the released amino groups and CO2.3.RE-dopped Nil.The RE@Nil fluorescence probe can be obtained from soaking with rare earth cations of Tb3+,Eu3+,Dy3+,and Sm3+.The results indicate that Tb3+@Nil is a green fluorescence probe to Fe3+ in aqeuous solution.The detection of Tb3+@Nil to Fe3+ exhibit high sensitivity,rapid response,excellent anti-interference,and reliable repeatability. |
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