| Uric acid(UA)and Serotonin are important bioactive substances in the human body,which involved in regulating various physiological processes of the human body.Paracetamol(PCT)is a commonly used antipyretic analgesic,which can be used to treat cold,joint pain,migraine and other diseases.UA,serotonin,and PCT all have electrochemically activities,which can be detected or measured by using electrochemical methods,and the oxidation potentials of the three are similar.Ionic liquid is a widely used organic molten salt solvent,which is used in many fields such as synthesis,catalysis,separation,analysis,materials and so on.In terms of the electrochemistry,ionic liquids are often used to prepare modified electrodes or sensors.At present,a variety of ionic liquid modified electrodes have been used to detect UA,serotonin and PCT.Therefore,studying the interaction of imidazolium ionic liquids with UA,serotonin and PCT can provide references for the selection of ionic liquids in the fabrication of modified electrodes or sensors.In this work,experiments and theory were combined to investigate systematically the interaction of UA with water,UA with imidazole ionic liquids,serotonin hydrochloride(SH)with water,SH and imidazole ionic liquids,PCT and imidazole ions.The effects of concentrations,structures and types of imidazolium ionic liquids on the electrochemical behavior of UA,SH and PCT were studied,and the mode and site of interaction of ionic liquid and UA/SH/PCT were discussed.The main contents of this dissertation are as follows:1.The interaction between UA and water was studied by UV-vis spectroscopy,cyclic voltammetry(CV),density functional theory(DFT),atomic theory in molecules(AIM)and natural bond orbital analysis(NBO).The results show that the carbonyl oxygen atoms of UA formed hydrogen bonds with the hydrogen atoms of water,and the hydrogen atoms on the imino group of UA formed hydrogen bonds with the oxygen atoms of water.In addition,the pH of solution has an effect on the electrochemical behavior of UA in water.2.The interaction of UA and seven imidazole ionic liquids in aqueous solution were studied by using CV,DFT,AIM,and NBO.The results show that the main action between them are the hydrogen bonds formed by the ionic liquid anion and the imino hydrogen atoms of UA,at the same time hydrogens on the cationic imidazole ring can form the hydrogen bonds with the carbonyl oxygen atoms of UA.The shorter the side chain of cations on ionic liquid is,and the stronger interaction of the anion and cation is,the weaker the hydrogen bond between ionic liquid and UA is.3.The interaction between SH and water was studied by CV,1H NMR,DFT,AIM and NBO.The results show that the phenolic hydroxyl and imino groups of SH can form hydrogen bonds with water,and?-?stacking can be formed between SH molecules,when the concentration of SH is larger.4.The interaction of seven imidazole ionic liquids and SH in aqueous solution was studied by CV,~1H NMR,DFT,AIM and reduced density gradient method(RDG).The results show that there is?-?stacking between the imidazole ring of ionic liquid and the benzene ring and the pyrrole ring of SH,The hydrogen atom on imidazole ring forms C-H···?interaction with SH benzene ring,and the anion can form hydrogen bond with phenolic hydroxyl group and amino group in SH.The longer the side chain on cation in ionic liquid,and the larger volume of the anion is,the weaker C-H···?interaction and?-?stacking between ionic liquid and SH is.5.The interaction of imidazole ionic liquid and PCT was studied by CV,~1H NMR,DFT,AIM and RDG.The results show that the anionic of ionic liquid can form hydrogen bonds with the phenolic hydroxyl group and the imino group of PCT,while the benzene ring of PCT can form?-?stacking with the imidazole ring of ionic liquid.The interaction between ionic liquid and PCT can be affected by the length of the side chain on cation and the type of the anion of ionic liquid. |
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