A newly developed highly selective ratiometric fluoride ion sensor: Spectroscopic, NMR and density functional studies

Abstract

A new easy-to-synthesize chemosensor, 3,3'-bis(indolyl)-4-chlorophenylmethane (hereafter S), was designed, synthesized and employed as a selective optical chemosensor for fluoride ions.(1)H NMR and density functional studies on the system have been carried out to determine the nature of the interaction between S and X(-) (X = inorganic anions) responsible for the significant fluoride-induced changes in the absorption properties of S. The experimental results reveal that abstraction of an acidic proton of S by the fluoride ion, leading to the formation of anionic species, is responsible for the spectral changes. These changes allow signaling for the fluoride ion to detect and estimate the concentration of fluoride ion present even at the submicromolar level, accurate up to 2 μM. Calculations of the transition energies of S, S(-), and S···F(-) (hydrogen bonded complex) show that only S(-) is responsible for the long-wavelength absorption band in the presence of F(-).

Two new indole derivatives as anion receptors for detecting fluoride ion

“…In particular, great effort has been devoted to the recognition of the fluoride ion, because it is highly relevant to environmental and health issues [5][6][7][8][9][10][11][12][13][14]. Several successful examples have been reported [15][16][17][18][19][20], e.g., the receptors based on the chemical affinity between fluoride and silicon can exhibit high selectivity for F À [21][22][23], but the rational design of F À receptors with remarkable fluorescent or colorimetric response is still a great challenge. One of the design strategies of fluoride receptors is based on the formation of a hydrogen bond between the fluoride ion and the active N-H group of an organic chromophore, which will result in a detectable change of spectral characteristicsof the chromophore upon the recognition of fluoride ion.…”

Intramolecular charge transfer and sensing mechanism for a colorimetric fluoride sensor based on 1,8-naphthalimide derivatives

“…There are a series of ratiometric chemosensors for fluoride anion having been developed with the strategy that involves the hydrogenbonding interactions [12][13][14], the Lewis acid/base interactions [13,15,16] and the fluoride-triggered Si(B, C)-O cleavage reactions [1-3, 6, 17, 18]. Among these chemosensors, those with tert-butyldimethylsilyl and tert-butyldiphenylsilyl belong to the reaction-based type [2] and exhibit higher selectivity and stability.…”

“…The photophysical properties and geometries of these chemosensors can be inferred from the measured 1 H NMR spectra, time-resolved absorption spectra and fluorescence spectra in the study of the Si-O bond cleavage, ICT and ESPT processes [2,13]. As a complement to the experimental techniques, the density functional theory (DFT)/time-dependent functional theory (TD-DFT) methods are also suitable for studying the ICT, ESPT and photoinduced electron transfer processes by presenting direct and detailed information on geometries and other properties of chemosensors [16,[21][22][23][24][25][26].…”

Loading, Unloading and Receiving of Selected Molecules with Nanomolar Sensitivity in Molecular Communication: Unprompted Carrier‐to‐Carrier Transformation

“…Detection of several ions and molecules is one of the current needs of this society to minimize the threat posed by these chemical species. Driven by these necessities, several artificial optical receptor molecules, self‐assembled nanostructures and nanocomposites, were designed and developed for the selective and sensitive recognition of ionic and neutral species. However, their efficiency was limited for lonely situations only.…”