Synthesis And Properties Of Li-based Metal-Organic Framework

Metal-organic frameworks(MOFs)have shown great promise in various applications,such as adsorption,catalysis and fluorescence sensing.Among them,Li-based MOFs have attracted attention for their unique advantages,such as small radius,high polarizability,and low toxicity.However,lithium feature with few coordination number,small atomic volume,and low ion valence,thus the synthesis of Li-based MOFs is still a challenge.In this thesis,organic ligands were rationally selected to synthesize novel Li-based MOFs,and their fluorescence and catalytic properties were explored.The main research results of this thesis were list as follows:1.A Li-based MOF,[Li4L(DMF)2]n(HNU-28),was successfully synthesized under solvothermal reaction by using 5-(Bis-carboxymethyl-amino)-isophthalic acid(H4L)and LiNO3.Structural analysis indicated that HNU-28 was a neutral 3D framework which was formed by the connection of Li chain and L4-ligands.The study of the fluorescence properties showed that HNU-28 can be used as a fluorescence sensor to detect Al3+ions with a limit of detection 4×10-6 M.This was the first example for detecting Al2+ions by using Li-based MOF as a fluorescence detector.2.Two Li-based MOFs,{2[LiM(TDA)2(DMF)]·NH2+(CH3)2·solvents}n(M=Co,HNU-29)?(M=Zn,HNU-30),were successfully synthesized by introducing two metal ions of CoCl2/LiNO3 or ZnCl2/LiNO3 and 2,5-thiophenedicarboxylic acid(H2TDA)ligands under solvothermal reaction.The structural analysis showed that the two Li-based MOFs were isomorphic,and its metal secondary building units were connected by TDA2-ligand to form a 3D framework.The metal unit can be regarded as 4-connected node,and the frameworks can be simplified as 2-fold dia nets with the point symbol of {66}.HNU-29 exhibits excellent photocatalytic activity for the degradation of methylene blue(MB)under visible light without the addition of electron acceptor H2O2.Moreover,HNU-29 also shows good stability and recyclability.3.Two Li-based MOFs,[Li2(FUM)2]·NH2+(CH3)2(HNU-31)and[Li2SA]n(HNU-32)were successfully synthesized by using bidentate carboxylic ligands 2,5-furandicarboxylic acid(FUM)and succinic acid(SA)with Li+.HNU-31 was a 3D framework formed by tetranuclear lithium cluster connected ligands.HNU-32 was formed by the linkage of Li+ and SA,forming a framework with a zeolite structure.If the two carbon atoms of SA were eliminated,the overall framework can be simplified to a CHA topology of molecular sieve type.