Please use this identifier to cite or link to this item:
|Title:||Fluoride ion receptors based on dipyrrolyl derivatives bearing electron-withdrawing groups: Synthesis, optical and electrochemical sensing, and computational studies|
|Citation:||Ghosh, T., Maiya, B.G., Wong, M.W. (2004-12-23). Fluoride ion receptors based on dipyrrolyl derivatives bearing electron-withdrawing groups: Synthesis, optical and electrochemical sensing, and computational studies. Journal of Physical Chemistry A 108 (51) : 11249-11259. ScholarBank@NUS Repository. https://doi.org/10.1021/jp0464223|
|Abstract:||Two dipynolyl derivatives, 2,3-di(1H-2-pyrrolyl)-7,12-dihydronaphtho[2,3-f] quinoxaIine-7,12-dione (1) and 5,6-di(1H-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 - inding by receptor 1 is ∼1.6 × 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.|
|Source Title:||Journal of Physical Chemistry A|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Jun 16, 2018
WEB OF SCIENCETM
checked on May 8, 2018
checked on Jun 1, 2018
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.