Reaction‐Based Colorimetric and Ratiometric Fluorescence Sensor for Detection of Cyanide in Aqueous Media

Abstract

A stilbene-based compound (1) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F(-), Cl(-), Br(-), I(-), ClO(4)(-), H(2)PO(4)(-), HSO(4)(-), NO(3)(-), and CH(3)CO(2)(-). A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron-deficient cyanoacrylate group of 1. The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge-transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations.

Sensing mechanism for a fluoride chemosensor: invalidity of excited-state proton transfer mechanism

“…Given the obvious ICT character of the first excited state of DBMO, its UV-vis absorption spectra and fluorescence emission spectra distinctly red shifted compared with DBM. 11,52 Thus, DBM is an excellent candidate for a colorimetric and ratiometric fluorescent chemosensor for fluoride anions.…”

A simple 7-azaindole-based ratiometric fluorescent sensor for detection of cyanide in aqueous media

“…The electrophilic nature of the dicyanovinyl substituent can be modulated by CN À , which interrupts the p-conjugation [35], with its role as a sensing mechanism clarified by a comparison with the spectrum of 1-methyl-7-azaindole [36]. The synthesis of 1 is readily prepared through a condensation of aldehyde 2 with malononitrile in the presence of triethylamine.…”

Sensing mechanism of a ratiometric near-infrared fluorescent chemosensor for cysteine hydropersulfide: Intramolecular charge transfer

“…Up to now, a mass of ratiometric fluorescent chemosensors have been synthesized by chemists 16,17,[21][22][23][24][25][26][27][28] . It has been demonstrated that they can quantitatively detect bioactive molecules both in vitro and in vivo 17,24,25,[28][29][30] . To the best of our knowledge, attentions are mainly focused on the novel synthesis of fluorescent chemosensors, and most of the sensing mechanisms are based on speculation 17,24,25,[28][29][30] .…”

“…It has been demonstrated that they can quantitatively detect bioactive molecules both in vitro and in vivo 17,24,25,[28][29][30] . To the best of our knowledge, attentions are mainly focused on the novel synthesis of fluorescent chemosensors, and most of the sensing mechanisms are based on speculation 17,24,25,[28][29][30] . Nevertheless, explorations on the sensing mechanisms of fluorescent chemosensors are also essential to design more effective fluorescent chemosensors.…”

“…Until now, numerous sensing mechanisms have been proposed and elucidated for designing fluorescent chemosensors, including the intramolecular charge transfer (ICT) 17,22,[30][31][32][33][34][35][36] , the photoinduced electron transfer (PET) 8,9,[37][38][39][40] , the excited state proton transfer (ESPT) 16,[41][42][43][44][45] , and the fluorescence resonance energy transfer (FRET) [46][47][48][49][50] . Thereinto, ICT mechanism is usually adopted to design the ratiometric fluorescent chemosensors 17,21,22,29,34,51,52 .…”