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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Fluoride Ion Receptors Based on Dipyrrolyl Derivatives Bearing Electron-Withdrawing Groups:Synthesis,Optical and Electrochemical Sensing,and Computational Studies
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Fluoride Ion Receptors Based on Dipyrrolyl Derivatives Bearing Electron-Withdrawing Groups:Synthesis,Optical and Electrochemical Sensing,and Computational Studies

机译：基于带有电子吸收基的双吡咯基衍生物的氟离子受体：合成，光学和电化学传感以及计算研究

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摘要

Two dipyrrolyl derivatives,2,3-di(lH-2-pyrrolyl)-7,12-dihydronaphtho[2,3-f]quinoxaline-7,12-dione(1)and 5,6-di(lH-2-pyrrolyl)-2,3-pyrazine-dicarbonitrile(2),bearing electron-withdrawing quinone or dicyano subunits,have been synthesized and fully characterized by various spectroscopic and electrochemical methods.Both 1 and 2 are specific binders of F" in organic solvents and show dramatic,binding-induced changes in their color(observable in the naked-eye experiments)and also optical and electrochemical signatures.These F~-induced color changes remain the same even in the presence of a large excess of Cl~-,Br~-,I~-,or ClO_4~-,thus rendering 1 and 2 to be efficient fluoride ion sensors.While K_a for F~-binding by receptor 1 is ~ 1.6 x 10~4 M~(-1),that for receptor 2 is an order of magnitude higher.~1H NMR titrations were carried out to monitor the binding of 1/2 with F~-.These experiments not only provide evidence for the hydrogen-bonding interaction between the pyrrolic NH groups of these receptors and F~,but also offer some key insights into the structures of the receptor-anion complexes.Further insights into the structures of the receptor-anion complexes and the observed binding discrimination have been obtained by density functional calculations.Both receptors 1 and 2 interact with a halide ion by forming two NH..X~-hydrogen bonds with the pyrrolic NH protons in a bidentate fashion.The predicted order of halide binding affinity for receptors is F Cl > Br.The high selectivity for F~-among the halides is attributed mainly to the strength of the hydrogen bond and partly to the complementarity of the geometries between the receptor and anion.The higher F~-binding ability of 2 over 1 has been interpreted in terms of the greater electron deficiency and enhanced hydrogen-bond-donating character of the former derivative.Calculations of the NMR and UV-visible spectra support the experimental characterization of the receptor-anion complexes.
机译：两种二吡咯基衍生物2,3-二（1H-2-吡咯基）-7,12-二氢萘并[2,3-f]喹喔啉-7,12-二酮（1）和5,6-二（1H-2-）带有吸电子醌或二氰基亚基的吡咯基）-2,3-吡嗪-二腈（2）已经合成，并通过各种光谱和电化学方法进行了全面表征。1和2均为有机溶剂中F“的特定粘合剂表现出显着的，由结合引起的颜色变化（在肉眼实验中可以观察到）以及光学和电化学特征。即使在存在大量的Cl〜-，Br的情况下，这些由F〜引起的颜色变化仍然相同。 〜-，I〜-或ClO_4〜-，因此使1和2是有效的氟离子传感器。而通过受体1进行F〜结合的K_a为〜1.6 x 10〜4 M〜（-1），受体2的数量级要高一个数量级。〜1H NMR滴定法监测1/2与F〜-的结合，这些实验不仅提供了它们的吡咯NH基团之间氢键相互作用的证据。 e受体和F〜，但也提供了一些对受体-阴离子配合物结构的关键见解。通过密度泛函计算获得了对受体-阴离子配合物结构的进一步见解和观察到的结合区分。两种受体1和2与卤化物离子相互作用，通过与吡咯的NH质子形成两个NH.X〜氢键成双齿状。卤化物对受体的结合亲和力的预测顺序为F Cl> Br。对F〜的高选择性-卤化物中的-主要是由于氢键的强度，部分是由于受体和阴离子之间的几何形状的互补性.F +结合能力大于2大于1的原因是电子缺陷和电子缺陷增多。 NMR和UV-可见光谱的计算支持了受体-阴离子配合物的实验表征。

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