Development And Application Of Calixarene Functionalized Carbon Material Electrochemical Sensor

As new generation supramolecular macrocyclic compounds,calixarenes have attracted considerable attention from scientists in recent years.Their unique molecular recognition performances have been widely used in the many fields,such as supramolecular chemistry,material chemistry,biochemistry and medicine.In this dissertation,calixarenes with supermolecular recognition and carbon nanometer materials such as graphene and carbonnanotubes have been effectively combined.At the same time,they combined with gold nanoparticles,which have the excellent catalytic performance.A variety of functional carbonnanocomposites with synergistic effects were designed and prepared.The organic combination between carbon nanomaterials,supramolecular main compounds and noble metal nanoparticles was realized.The composite nanomaterial with carbon nanomaterials,supramolecular main compounds and noble metal nanoparticles were applied to electrochemical analysis to detect organic small molecules.The main research works in this dissertation are divided into the following five parts:1.A theoretical study on the interaction between calixarenes and grapheneIn this chapter,two series of calixarene derivatives are systematically investigated via.theoretical calculation.One series are 4-tert-butylcalix[n]arenes(n=4,6,8),and the bottom rims of 4-tert-butylcalix[n]arenes(n=4,6,8)are substituted by ester chains as another series.The molecular geometry,electronic structure of calixarene derivatives were obtained usingdensity functional theory(DFT)at the B3LYP/6-31G(d)level of theory.It is found that the structure of calixarene derivatives will change regularly accompanied by the increase in thenumber of constituent units,which is due to the the presence of steric hindrance.In addition,we also measure the interactions between calixarene derivatives and graphene by the method of Molecular dynamics(MD).The results of MD analysis indicated that the calixarene derivatives with ester chains have stronger interaction with graphenes compared to 4-tert-butylcalix[n]arenes(n=4,6,8);and with increase the number of rings calixarenederivatives can also enhance the interaction force with graphene in general.2.Electrochemical detection dopamine by ester-calix[n]arenes/craphene nanosheets modified electrodesOn the basis of theoretical calculation in the previous chapter,graphene nanosheets(GN)were modified by three ester-calix[n]arenes(ECnA,n=4,6,8)in N'N-Dimethylformamide(DMF)through ?-? interaction.The dispersion and stability of graphene in organic solvents were improved using the simple self-assembly strategy.The reliability of the theory is proved by experiments.Three obtained ECnA/GN nanocomposites were characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,scanning electron microscope and electrochemical impedance spectroscopy,which confirmed that the various amount of ECnA molecules had been effectively loaded onto the surface of GN.Cyclic voltammetry(CV)and differential pulse voltammetry(DPV)measurements showed that the ECnA/GN modified electrodes exhibited high supramolecular recognition and enrichment capability and consequently displayed high electrochemical response toward dopamine(DA).At low concentration of guest molecule,the ECnA/GN modified electrodes show the better enrichment performances.Especially,EC8A/GN modified electrode exhibited an excellent electrochemical performance for DA with high current densities of 4.46 mA mmol-1 L cm-2,broad linear range(5×10-7 molL-1?4×10-4 molL-1)and low detection limit(2×10-7 molL-1)at a signal-to-noise ratio of 3.Electrochemical test results showed that the electrochemical properties of modified electrode were improved with the increase of the number of benzene rings in the calix[n]arenes.3.Study of self-assembly thiolated calix[n]arene(n=4,6,8)modified gold nanoparticles on graphene nanosheetsTo the introduction of gold nanoparticles on the surface of graphene,the gold nanoparticles(AuNPs)coated thiolated calix[n]arene(TCnA,n=4,6,8)were firstly synthesized.The influences of concentration ratio between TCnA and HAuCl4 and reaction temperature on particle size and aggregation morphology of gold nanoparticles were studied.The experimental results show that when the concentration of TCnA and HAuC.l4 concentration is 1:1,the morphology of AuNPs is more uniform.Then,TCnA-AuNPs were modified on the surface of graphene nanosheets(GN)by the interaction between TCnA and GN to prepare the TCnA-AuNPs/GN ternary composite nanomaterials.The ternary composite nanomaterials were characterized by Fourier transform infrared spectroscopy,transmission electron microscope,X-ray powder diffraction and X-ray photoelectron spectrometry.The characterization analysis confirmed the formation of TCnA-AuNPs/GN ternary composite nanomaterials.The surface load was gradually increased with the increase of the number of benzene ring units in TCnA(n=4,6,8),which is consistent with the modification of the pure calixarene on the GN surface.4.Electrochemical detection dopamine and paracetamol on thiolated calix[n]arene(n=4,6,8)-gold nanoaprticles/graphene nanosheets modified glass carbon electrode.On the basis of the previous chapter,TCnA-AuNPs/GN ternary composite nanomaterials were used as electrode materials to fabricate the modified electrodes.The modified electrodes were applied to detect dopamine(DA)and paracetamol(PCM).The electrochemical test results showed that the electrochemical properties of the modified electrode gradually increased with the mumber of benzene ring units in TCnA(n=4,6,8).Especially,TC8A-AuNPs/GN modified electrode exhibited an excellent electrochemical performance for DA with high current densities of 6.08 mA mmol-1 L cm-2,and low detection limit(1.0×10-7 mol L-1)at a signal-to-noise ratio of 3.TC8A-AuNPs/GN modified electrode also showed the good electrochemical performance for PCM with high current densities of 2.94 mA mmol-1 L cm-2,and low detection limit(8.0×10-7 mol L-1)at a signal-to-noise ratio of 3.The TCnA-AuNPs/GN/GCE modified electrode performance is significantly better than the ECnA/GN/GCE modified electrode in the third chapter.This confirmed the good synergistic effects among the three materials.The introduction of gold nanoparticles on the graphene nanosheets effectively promoted the electrochemical performance of modified electrode.5.Preparation of thiolated calig[8]arene/AuNPs/MWCNTs modified glassy carbon electrode and its electrocatalytic oxidation toward paracetamolIn this chapter,the ternary nanocomposites modified electrode of thiolated calix[8]arene(TC8A)/electrodepositing gold nanoparticles(AuNPs)/multi-walled carbon nanotubes(MWCNTs)was constructed by the two-step method.During the preparation process of modified electrode,AuNPs were firstly in-situ growth on the MWCNTs/GCE surface by electrochemical deposition.Then,TC8A can self-assemble onto the surface of AuNPs through thiol groups to form ternary nanocomposites modified electrode.The modified electrode was characterized by Fourier transform infrared spectroscopy,scanning electron microscope and cyclic voltammetry.The modified electrode was applied to detect paracetamol(PCM).Cyclic voltammetry measurement showed that the TC8A/AuNPs/MWCNTs/GCE electrode exhibited the good electrocatalytic activity and displayed the high electrochemical response toward PCM compared to bare glass carbon electrodes and other modified electrodes.The excellent electrochemical performances are attributed to the electrocatalytic activity of MWCNTs and AuNPs,and the enrichment capability of TC8A for PCM.The three materials fully demonstrate their respective characteristics and play a synergistic role.The synergistic effects of three materials improve electrochemical properties of modified electrode.