New Chromogenic and Fluorescent Probes for Anion Detection: Formation of a [2 + 2] Supramolecular Complex on Addition of Fluoride with Positive Homotropic Cooperativity

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• 作者：Chan-Yu Chen ; Tzu-Pin Lin ; Chine-Kun Chen ; Su-Ching Lin ; Mei-Chun Tseng ; Yuh-Sheng Wen ; Shih-Sheng Sun
• 刊名：Journal of Organic Chemistry
• 出版年：2008
• 出版时间：February 1, 2008
• 年：2008
• 卷：73
• 期：3
• 页码：900 - 911
• 全文大小：1087K
• 年卷期：v.73,no.3(February 1, 2008)
• ISSN：1520-6904

文摘

Two new chromogenic and fluorescent probes for anions have been designed, synthesized, andcharacterized. These probes contain multiple hydrogen bonding donors including hydrazine, hydrazone,and hydroxyl functional groups for potential anion interacting sites. Despite the possible flexible structuralframework due to the presence of sp³ carbon linkage, X-ray structure analysis of probe 2 displayed anessentially planar conformation in the solid state owing to strong crystal packing interactions comprisinga combination of favorable - stacking effect and hydrogen bonding to cocrystallized CH₃OH molecules.Both probes 1 and 2 display orange color in DMSO solution and show fairly weak fluorescence at roomtemperature. Binding studies revealed that both probes 1 and 2 show noticeable colorimetric and fluorescentresponses only to F^-, OAc^-, and H₂PO₄^- among the nine anions tested (F^-, Cl^-, Br^-, I^-, OAc^-, H₂PO₄^-,HSO₄^-, ClO₄^-, and NO₃^-). The general trend of the sensitivity to anions follows the order of F^- >OAc^- > H₂PO₄^- > Cl^- > Br^- I^- HSO₄^- ClO₄^- NO₃^-. A 1:2 (probe to anion) bindingstoichiometry was found for probe 1 with OAc^- and H₂PO₄^- and probe 2 with F^-, OAc^-, and H₂PO₄^-.The binding isotherm of probe 1 to F^- was found to be complicated with apparent multiple equilibriaoccurring in solution. The formation of an aggregated supramolecular complex upon addition of fluorideis proposed to rationalize the observed optical responses and is supported by ESI mass spectrometry andpulsed-field gradient NMR spectroscopy. Data analysis suggests that the binding of probe 1 to F^- showspositive homotropic cooperativity.