Selective anion recognition by inhibition of excited state intramolecular proton transfer process via hydrogen bonding interaction and efficient deprotonation: Spectroscopic and theoretical investigation

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• 作者：Anuva Samanta ; Sasanka Dalapati ; Nikhil Guchhait ; ^{nikhil.guchhait@rediffmail.com} ; ^{nguchhait@yahoo.com}
• 关键词：5-(4-Fluoro-phenyl)-2-hydroxy-nicotinonitrile ; 5-(4-Fluoro-phenyl)-2-hydroxypyridine ; Hydrogen bonding ; Proton abstraction ; Tetra-n-butylammonium ; Hartree Fock
• 刊名：Journal of Photochemistry and Photobiology A ; Chemistry
• 出版年：2012
• 期刊代码：66_10106030
• 类别：ch
• 出版时间：15 March, 2012
• 卷：232
• 期：Complete
• 页码：64-72
• 文件大小：2070 K

摘要

Anion (X) recognition fluorescent chemosensor 5-(4-Fluoro-phenyl)-2-hydroxy-nicotinonitrile (FP2HN) having both -NH and -OH groups in its two tautomeric forms has been synthesized and its excited state intramolecular proton transfer (ESIPT) reaction has been investigated by UV-vis, fluorescence, ¹H NMR spectroscopy in combination with computational calculations. The experimental findings show that FP2HN selectively recognizes F^{鈭?/sup>, AcO鈭?/sup> and H₂PO₄鈭?/sup> ions through the formation of -N(O)H鈰疿 hydrogen bonding (HB) complex. The binding constant obtained by non-linear fit predicts the binding order of F鈭?/sup> > AcO鈭?/sup> > H₂PO₄鈭?/sup> > Cl鈭?/sup>. The ESIPT process of FP2HN is inhibited either by the fluoride induced deprotonation of acidic proton of FP2HN or by the formation of a strong -N(O)H鈰疿 intermolecular hydrogen bonding complex. Further insights into the recognition mechanism of the receptor-anion complexes using ab initio calculations have been performed which support the experimental binding affinity order of F鈭?/sup> > AcO鈭?/sup> > H₂PO₄鈭?/sup> > Cl鈭?/sup>.}