Effects of Ionic Liquids on Fluorescence Characteristics of 17α- and 17β-estradiol
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Herein, we report the effects of six different room temperature ionic liquids (RTILs) on fluorescence spectra of 17α-estradiol (EE1) and 17β-estradiol (E2). The selected RTILs belonged to the compound classes of 1-alkyl-3-methylimidazolium tetrafluoroborate ([CnMIM]BF4) and 1-alkyl-3-methyl imidazolium hexafluorophosphate ([CnMIM]PF6). RTILs had a gradual quenching effect on fluorescence intensity (FI) of EE1 and E2, and the quenching process followed the well-known Stern-Volmer theory. The quenching mechanism of EE1 and E2 by RTILs was demonstrated to be dynamic quenching. Additionally, the overall quenching efficiency by [CnMIM]BF4 was higher than [CnMIM]PF6. The increased carbon chain length of RTILs did not lead to obvious differences in FI for EE1 and E2. The quenching efficiency showed irregular trend at three different temperatures (25, 35 and 45 °C). RTILs such as [C4MIM]PF6 had the different fluorescent effects on organic chemicals with different fluorophores. The enhancing effects of [C4MIM]PF6 were observed on strong fluorescence chemicals (dansyl chloride, rhrodamine B, 1,10-phenanthroline, norfloxacin), while quenching effect on weak fluorescence chemicals (EE1 and E2). In theory, these results provide a theoretical foundation for deep insight into their interaction mechanism between RTILs and estradiol.
KeywordsRoom temperature ionic liquids Fluorescence intensity 17α-Estradiol 17 β-Estradiol Quenching mechanism
This work was jointly funded by National Natural Science Foundation of China (21077079), International Cooperation Project of Wenzhou City (H20100053, H20100054) and Public Benefit Project of Zhejiang Province (2011C23114, 2011C37006, 2011B25).
- 8.Deng X (2008) The preliminary study on the application of ionic liquids in fluorescent analyses Master’s thesis. Southwest University of China, ChongqingGoogle Scholar
- 25.Zou YJ, Wang HL, Wang WW, Ma MP, Wang P, Wang CJ, Wang XD (2012) The effect of imidazolium room temperature ionic liquids on the fluorescent properties of Norfloxacin. Luminescence. doi: 10.1002/bio.1382
- 27.Baker SN, Baker GA, Kane MA, Bright FV (2001) The cybotactic region surrounding fluorescent probes dissolved in 1-Butyl-3-methylimidazolium hexafluorophosphate: effects of temperature and added carbon dioxide. J Phys Chem A 105:9663–9669Google Scholar
- 28.Gao L, Guo B, Duan EH, Ren AL (2011) The viscosities of [bmim][BF4] and [bmim][PF6] ionic liquids and their binary systems with N-Dimethylformamide. Hebei Chem Ind 34:40–44Google Scholar
- 29.Xu JG, Wang ZB (2006) Fluorimetry, revised 3rd edn. Science and Technology Press, ChinaGoogle Scholar