Synthesis And Properties Of Multifunctional Metal Organic Framework Materials

Luminescent metal organic framework is a kind of multifunctional porous material with specific micropore structure and excellent luminescence properties.It has potential applications in the detection of environmental pollutants and the photocatalytic degradation of organic dyes.In this paper,we selected Eu(?)and Tb(?)as metal ions,with 2,5-thiophenedicarboxylic acid(L1)as the organic linkers to synthesize two MOFs,[Eu2(L1)3(CH3OH)2(CH3OH)](MOF1),[Tb2(L1)3(CH3OH)2(CH3OH)](MOF2),and a mixed lanthanide MOF[Eu2.5Tb2.5(L1)7(NO3)(CH3)(OH)2(CH3OH)5]·(CH3OH)0.5(H2O)(MOF3).Besides,we combined Zn(II)and 2,5-bis-(3,5-dicarboxyphenyl)thiopheneamide(L2)to synthesize[Zn2(L2)(4,4'-bpy)(CH3OH)(H2O)2]·3.5(H2O)(CH3OH)(MOF4).MOFs are characterized by single-crystal X-ray diffraction analysis,infrared spectrum(FTIR),X-ray powder diffraction(XRD)and thermogravimetric(TG).Their photophysical properties are also studied by UV-Vis diffuse reflectance spectroscopy(DRS),fluorescence spectrum(PL)and so on.The result shows that MOFs have outstanding optical properties,and MOF3 has complex three-dimensional framework structure.The fluorescence properties of MOF1 and MOF2 on sensing of aromatic amines and metal ions were studied.The experimental suggesting that MOF1 and MOF2 have high-sensitivity sensing p-nitroaniline and Fe3+ ions with a fluorescence quenching effect.In addition,diphenylamine significantly enhanced the ligand-based emission of MOF2 under the same experimental conditions.These features make MOF1 and MOF2 promising candidates for the development of efficient and multifunctional sensors in the future.For MOF4,luminescent investigations reveal that MOF4 has dual-functional sensing performance,which can sense anilines,Al3+ions,and Mn042-selectively through fluorescence enhancement or quenching effect.Additionally,the photocatalysis activities of MOF4 and Fe3+ doped composite material Fe3+@MOF4 for degradation of Rhodamine B(RhB)were also studied.The experiment results show that Fe3+@MOF4 has the improved photocatalytic activity than MOF4,suggesting that doping Fe3+ ions into the framework of MOFs would be an ideal option for enhancing their photocatalytic activities.