Properties And Spectral Analysis Of Imidazolium Ionic Liquids

Room temperature ionic liquids are one of the most widely studied substances inthe present time.Imidazole ionic liquids,the most common type of ionic liquids in room temperature ionic liquids,have many contacts in analytical chemistry.Ionic liquids,due to their unique molecular structures and properties,are helpful to improve the performance and application prospects of spectral technology.The importance of ionic liquids in modern spectroscopy and the importance of various spectral techniques in the understanding of ionic liquids.Therefore in this experiment,six kinds of imidazolium ionic liquids,PMI-NO₃,BMI-NO₃,AMI-NO₃,HMI-NO₃、HEMI-NO₃ and OMI-NO₃ respectively.The two ionic liquids HEMI-NO₃ and OMI-NO₃ were characterized and quantified by UV spectroscopy in different solvents（deionized water,absolute ethanol,and the acetonitrile）.UV absorption spectrum curve,quantitative curve and standard working curve were obtained at room temperature,and the recoveries of the standard addition method were between 94.1%and 104.8%.The fluorescence intensity of rhodamine B in PMI-NO₃,BMI-NO₃,AMI-NO₃,HMI-NO₃,HEMI-NO₃,OMI-NO₃ and deionized water was analyzed by fluorescence spectroscopy.With the increase of concentration,the fluorescence intensity of rhodamine B also increased gradually.However,the ionic strength of rhodamine B had no significant effect on the fluorescence intensity of rhodamine B under different alkyl chains.The fluorescence spectra of six ionic liquids PMI-NO₃ BMI-NO₃,AMI-NO₃,HMI-NO₃,HEMI-NO₃ and OMI-NO₃ were analyzed in different solvents,water ethanol mixtures and pH values.Acetonitrile obtained solvent solubility is better,its fluorescence intensity is also the largest However,the fluorescence intensities of different mixed solutions of water and ethanol were different,but the fluorescence intensities of the six ionic liquids were the best under water 20%ethanol 80%.The determination in different pH showed that the fluorescence intensity was better under acidic conditions,while under alkaline conditions,the fluorescence intensity was decreased.This shows these six ionic liquids are more suitable for acidic conditions.The solubility tests of seven ionic liquids such as PMI-NO₃,BMI-NO₃,AMI-NO₃,HMI-NO₃,HEMI-NO₃ and OMI-NO₃ were tested by infrared spectroscopy.The infrared absorption spectra of these six ionic liquids under deionized water,absolute ethanol and acetonitrile as solvents were determined,and the recovery tests were carried out.The recoveries of these ionic liquids were between 95.3%-102.8%.