Preparation And Applications Of The Nanocomposites Based On Cucurbit[n]uril

Nanomaterials have unique physical and chemical properties compared to common general materials so that they have attracted the interest of the scientists in the field of fundamental research and applied research over the past few decades.At the same time,with the development of supramolecular chemistry,many macrocyclic supramolecular hosts have also been used to prepare nanomaterials,especially in the preparation and stabilization of metal nanomaterials.The application of macrocyclic supramolecular hosts for the preparation of organic-inorganic hybrid nanomaterials not only can play the respective functions of supramolecular hosts and metal nanomaterials,but also bring about new properties and potential applications generated by the synergistic effect of the two,which is of great significance for the development of new materials and their applications in many fields.This thesis based on the macrocyclic host cucurbit[n]uril and gold nanoparticles?AuNPs?,the cucurbit[n]uril capped gold nanoparticles,carbon nanomaterials and carbon-gold hybrid nanomaterials were prepared and their applications in catalysis,enzyme simulation and electrochemical energy storage were studied.The main content consists of the following three parts:In the first part:Firstly,different sizes of cucurbit[5-8]uril-modified AuNPs were prepared by using cucurbit[5-8]uril with a simple and green one-pot mathod,and they were characterized by TEM,UV-Vis,XRD and FTIR.The nanoparticle sizes can be well controlled by cucurbit[n]uril?n=5,6,7,8?with different ring sizes,as the ring size of cucurbituril increases,the size of the prepared AuNPs also increases in turn,the diameter of four cucurbit[n]uril?n=5,6,7,8?capped AuNPs are 4.6±0.7,10.4±1.6,12.4±1.8 and15.5±2.5 nm,respectively.Then,The coverage of four kinds of cucurbit[n]urils on AuNPs surface was calculated by TEM and TGA analysis,it was found that with the increase of the ring size of cucurbituril,their coverage on the surface of AuNPs increased,the coverage of four kinds of cucurbit[n]urils on AuNPs are 13,25.6,43.8 and 83.9%,respectively.Finally,the factors affecting the size of AuNPs and the mechanism of growth of AuNPs were investigated.It was found that the amount of cucurbituril carbonyl oxygen did not affect the size of AuNPs,but the more carbonyl oxygen there was,the more AuNPs could be reduced.In addition,the growth mechanism of AuNPs is first nucleated and gradually grown,then cucurbit[n]urils were modified to its surface.In the second part:Firstly,the catalytic properties of four different cucurbit[n]urils modified AuNPs were investigated by NaBH₄ reduction of 4-nitrophenol?4-NP?as a"catalytic model reaction",the catalytic reaction rate constants obtained are 11.55±1.36,7.17±0.34,5.98±0.17,1.95±0.09 min^-1,respectively.Then,explore the cucurbituril on the surface of AuNPs whether have the ability to catalyze NaBH₄ to reduce 4-NP,and quantify the area of AuNPs covered by cucurbituril with small molecules 2-mercaptobenzimidazole,adenine and amantadine hydrochloride.The relationship between the catalytic active site and the catalytic reaction rate showed that the lower the coverage of cucurbituril on the surface of AuNPs,the stronger the catalytic ability.Finally,the mechanism of the reaction of cucurbituril-modified AuNPs to catalyze the reduction of 4-NP by NaBH₄ was studied.It was found that this reaction also followed the Langmuir-Hinchelwood mechanism,in the first step,the NaBH₄ is decomposed by hydrolysis;then the active hydrogen is transferred to the AuNPs and adsorbed at the surface;finally,the active hydrogen at the AuNPs surface reacts with 4-NP to yield the product 4-AP.In the third part:Based on the previous AuNPs prepared with cucurbituril,we prepared carbon and carbon-gold nanocomposites directly by carbonized cucurbit[6]uril and cucurbit[7]uril and their modified AuNPs,and they were characterized by SEM,EDX,XRD and TEM.Subsequent studies have found that all the four materials have the activity of mimicking peroxidase,and these materials have the advantages of wider pH range and high temperature resistance compared to natural horseradish peroxidase.In addition,these carbonized materials can be used as capacitors for electrochemical energy storage,and carbon materials have better capacitive properties than carbon-gold nanocomposites.Finally,carbon material doped with nickel acetate can significantly improve the capacitance of carbon material,and when the concentration of nickel acetate is 0.3 mol/L,the capacitance of the doped carbon material can be increased by 4 times.