An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts |
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| Authors: | Zhaofu Fei Dr Dun‐Ru Zhu Prof Xue Yang Dr Lingjie Meng Dr Qinghua Lu Prof Wee?Han Ang Dr Rosario Scopelliti Dr Christian?G Hartinger Dr Paul?J Dyson Prof |
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| Institution: | 1. Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH‐1015 Lausanne (Switzerland), Fax: (+41)?21‐6939885;2. State Key Laboratory of Materials‐oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China);3. School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240 (China) |
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| Abstract: | A series of fluorescent imidazolium‐based salts containing the cation AnCH2MeIm]+ (in which An=anthracene and Im=the imidazolium cation) with Cl?, BF4?, PF6?, SO3CF3?, N(CN)2]?, N(SO2CF3)2]?, or PhBF3? anions have been prepared and characterized. X‐ray diffraction analysis of four of the salts reveals a number of C? H???X‐type (X=O, N, F) hydrogen bonds between the hydrogen atoms from the imidazolium ring and in some cases from the anthracene ring with the electronegative atoms of the anions. Additionally, C? H???π interactions can be found in all the salts analyzed by X‐ray diffraction, whereas π–π stacking is observed only in the salt containing the phenyltrifluoroborate anion. Fluorescence emission analysis in acetonitrile shows that the fluorescence of these salts varies significantly according to the nature of the anion, and correlates to the extent of ion pairing present in solution. Photodimerization of these salts was observed, and in one case a dimer has been isolated and characterized by X‐ray crystallography. |
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| Keywords: | fluorescence imidazolium salts ionic liquids structure elucidation |
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