Fluorescent “Turn-Off” Detection of Fluoride and Cyanide Ions Using Zwitterionic Spirocyclic Meisenheimer Compounds

Abstract

Stable zwitterionic spirocyclic Meisenheimer compounds were synthesized using a one-step reaction between picric acid and diisopropyl (ZW1) or dicyclohexyl (ZW3) carbodiimide. A solution of these compounds displays intense orange fluorescence upon UV or visible light excitation, which can be quenched or “turned-off” by adding a mole equivalent amount of F− or CN− ions in acetonitrile. Fluorescence is not quenched in the presence of other ions such as Cl−, Br−, I−, NO2−, NO3−, or H2PO4−. These compounds can therefore be utilized as practical colorimetric and fluorescent probes for monitoring the presence of F− or CN− anions.

Multistimuli-Responsive Fluorescent Switches Based on Spirocyclic Meisenheimer Compounds: Smart Molecules for the Design of Optical Probes and Electrochromic Materials

“…Because of this combination of properties, SZMCs appear as intriguing multiaddressable organic fluorescent switches that have already been demonstrated to operate on the single molecule level, behave as molecular analogues of field effect transistors, and allow the preparation of nanostructures, invisible security inks, and sensors of ammonia, ions , and explosives . Aiming to expand their applications, in this work the development of novel interconversion mechanisms for these systems is reported, with which we demonstrate their unique capacity to behave as both multistimuli-responsive and multistate fluorescent switches, and consequently, to perform as highly versatile chemical sensing platforms and smart materials.…”

Colorimetric sensing of acidic vapour through protonation of a Meisenheimer complex

“…The structure of these compounds is based on the Jackson–Meisenheimer intermediates of aromatic nucleophilic substitution reactions 39,40 . Scientists have applied them in various real‐life applications, including fluoride and cyanide sensors, moisture sensing, 41 as optical probes and electrochromic material, 42 in the preparation of nanostructures, 43 as fluorescent switches at the single molecule level, volatile organic compound sensors, 44 the removal of metal ions, fluoride and oil spills from water, and in stimuli‐responsive materials 35,37,45,46 . In general, the Meisenheimer complex contains a cyclohexadienyl anion system.…”

A Metallogel Based on a Zwitterionic Spirocyclic Meisenheimer Complex: Sensing of Fluoride Ions in Water and Moisture Content in Organic Solvents

“…Nowadays Meisenheimer complexes, the intermediates of aromatic nucleophilic substitution reaction, have come to the limelight because of their various stimuli‐responsive properties along with high fluorescence output. Very recently Meisenheimer complexes have been applied as on‐line ammonia sensor, security ink, picric acid detection, fluoride and cyanide sensor, water purification such as removal of metal ions, fluoride and oil spills, stimuli‐responsive materials etc . So this kind of complexes have become very much useful in terms of different practical points of view.…”