Synthesis And Properties Of Metal-Organic Frameworks Based On Benzotrithiophene Tricarboxylic Acid

Metal organic frameworks(MOFs)possess many advantages over traditional porous materials,such as zeolite and activated carbon,and they are widely applied in gas storage,separation,biomedicine,catalysis,fluorescence sensing and so on.In this paper,four kinds of threedimensional MOFs with different structures were prepared by solvothermal method using Benzotrithiophene tricarboxylic acid(BTTC)ligand with different metal ions.In addition,a new material was prepared by doping,and its performance in fluorescence recognition was studied.The results are shown below:(1)Two kinds of metal-organic frameworks(Pb-MOF and Mn-MOF)based on BTTC were prepared.These two materials can not only detect Fe3+ and ascorbic acid(AA)with specificity and high sensitivity,but also recognize strong carcinogenic Cr(VI)and volatile p-nitroaniline(PNA)by fluorescence quenching specifically.In addition,the detection of Fe3+ and AA can be estimated by producing a visually discernible "color-changerecover" effect in the low concentration.Finally,their mechanism of fluorescence sensing was studied by powder X-ray diffraction(PXRD),solid ultraviolet-visible diffuse reflectance(UV-vis),Fourier transform infrared spectroscopy(FT-IR)and X-photoelectron spectroscopy(XPS).The experimental results showed that both MOFs and analytes are tested through competitive energy absorption and redox process.This work reveals the advantages of MOFs with fluorescent properties as multifunctional fluorescent chemical sensors for sensing applications.(2)It is of great essence for environmental protection and human health to develop fluorescent probes based on MOFs to detect and distinguish heavy metal ions efficiently.In this chapter,Cd-MOF was synthesized and the fluorescence sensing experiment was carried out.Fe3+and Cr(VI)were detected by fluorescence "off",and Eu3+ was detected by"antenna effect".Cd-MOF demonstrated high sensitivity and specificity to these detectors,and had good anti-interference ability.In addition,a novel and effective ratio fluorescence probe was obtained by encapsulating Eu3+into the above skeleton,which showed excellent fluorescence performance in the detection of Cu2+.The detection limit(LOD)was as low as 0.014μM.More importantly,the sensitivity of Eu3+@Cd-MOF to Fe3+ was much higher than that of the original Cd-MOF,and its quenching constant KSV was increased by two orders of magnitude.It provides us a simple new sensor for rapid detection and differentiation of Fe3+ and Cu2+.(3)The Cu-MOF was synthesized based on the coordination of BTTC ligand with Cu(NO3)2·3H2O as a luminescent sensor.It could not only detect Fe3+ and AA with detection limits as low as 3.2 μM and 5.9 μM selectively and reversibly,but also detect small volatile PNA with a quenching constant as high as 104 M-1 specifically.Experimental studies showed that Cu-MOF could detect Fe3+,PNA and AA through competitive energy absorption and redox processes without destroying the original frame.This process yielded a highly reversible sensing cycle and easily recycled the Cu-MOF for further use.