醋酸N-正辛基吡啶离子液体在不同溶剂中的荧光光谱分析

离子液体具有熔点低、可忽略的蒸气压、电化学窗口宽、热稳定性高和良好的导电性等独特性能，引起了化学工业和相关领域的广泛关注。离子液体具有低蒸气压，不会造成空气污染，但这并不意味着它们对环境完全无害。大多数离子液体易溶于水，可能会因为意外泄漏或通过污水进入水生环境。常用离子液体BMIM]PF₆]和BMIM]BF₄]的水溶液中，很容易形成氢氟酸，磷酸，具有一定的腐蚀性。将离子液体列为绿色溶剂，也需要提供其关于代谢和降解的毒性、生态毒性研究数据，或者其对环境影响的数据，离子液体在不同溶剂中的检测方法是非常重要的。离子液体的光谱分析法用量较少、方法简单、结果准确。离子液体和许多有机溶剂互溶，可形成均一、稳定的溶液。荧光检测法具有灵敏度高，选择性好，线性范围宽和受外界干扰少等优点。本工作研究了醋酸N-正辛基吡啶（OP-OAc）离子液体在水、乙醇、乙腈、乙酸等4种溶剂中的荧光光谱。研究结果表明，OP-OAc离子液体在不同溶剂中的荧光强度：I_乙酸＞I_乙腈＞I_乙醇＞I_水；最大发射波长的大小顺序：λ_{em, 水}＞λ_{em, 乙醇}＞λ_{em, 乙腈}＞λ_{em, 乙酸}；它们的最大发射波长相对于激发波长发生红移；水中OP-OAc的荧光强度与浓度存在较高的相关性；当加入的甲醇、乙醇、乙腈溶剂不断增加时，OP-OAc离子液体的荧光强度增加，溶剂与水的比例为8∶2时，OP-OAc离子液体的荧光强度最强，溶剂的比例超过80%时，荧光强度突然降低；水中OP-OAc离子液体在pH 10时，荧光强度最高，在pH 14时，荧光强度最低。

Fluorescence Spectra Analysis of N-n-Octyl Oyridine Acetate Ionic Liquid in Different Solvents

Ionic liquids have attracted extensive attention in the chemical industry and related fields due to their unique properties such as low melting point,negligible vapor pressure,wide electrochemical window,high thermal stability and good electrical conductivity.Ionic liquids have low vapor pressure and do not cause air pollution,but that does not mean they are completely environmentally friendly.Most ionic liquids are soluble in water and may enter the aquatic environment through accidental leaks or sewage.Hydrofluoric acid and phosphoric acid are easily formed in the aqueous solution of commonly used ionic liquidsBMIM]PF₆]andBMIM]BF₄],which have certain corrosive properties.Therefore,classifying ionic liquids as green solvents also requires data on their toxicity,ecotoxicity studies of metabolism and degradation,or their impact on the environment.Therefore,the detection method of ionic liquid in different solvents is very important.The spectral analysis method of ionic liquid is simple and accurate.Ionic liquids are insoluble with many organic solvents to form homogeneous,stable solutions.The fluorescence detection method has the advantages of high sensitivity,good selectivity,wide linear range and less interference.We have studied the fluorescence spectra of OP-OAc ionic liquid in water,ethanol,acetonitrile and acetic acid.The study results show as follows:the fluorescence intensity of OP-OAc ionic liquid in different solvents is I_(acetic acid)>I_acetonitrile>I_ethanol>I_water;the order of maximum emission wavelength is λ_em,water>λ_em,ethanol>λ_{em,acetonitrile}>λ_(em,acetic acid);their maximum emission wavelength is redshifted relative to the excitation wavelength;the fluorescence intensity of OP-OAc ionic liquid in water is highly correlated with its concentration,as the experiment shows that the fluorescence intensity of OP-OAc ionic liquid increases with the addition of methanol,ethanol and acetonitrile,the fluorescence intensity of OP-OAc ionic liquid is the strongest when the ratio of solvent to water is 8∶2,and the fluorescence intensity decreases suddenly when the ratio of solvent exceeds 80%;the fluorescence intensity of OP-OAc ionic liquid in water is the highest when pH 10,and the fluorescence intensity is the lowest at pH 14.