Chromogenic and fluorogenic multianalyte detection with a tuned receptor: refining selectivity for toxic anions and nerve agents

Abstract

In the present study, a chemical probe was finely tuned for the highly selective and sensitive chromogenic and fluorogenic detection of toxic anions and a nerve agent. Studies on the binding sites, signaling units and spacers led to a receptor molecule, i.e., 2,7-bis-[3-(4-cyanophenyl)thiourea] fluorene 2, which detected multiple analytes such as fluoride, cyanide, and a tabun mimic. The optical responses obtained from all the three analytes were quite distinct from one another. More importantly, we have been successful in demonstrating the highly specific chromo-fluorogenic detection of a tabun mimic over other chemical warfare agents and reactive and non-reactive electrophilic interferents. In an attempt to mimic real-life scenarios, the applicability of our protocol was further extended to demonstrate the presence of a tabun mimic on solid surfaces, in the gas phase and in a spiked soil sample.

A Self-Degradable Hydrogel Sensor for a Nerve Agent Tabun Surrogate Through a Self-Propagating Cascade

“…The Kumar group has reported the analysis of cyanide due to its nucleophilic ability after being released from an analogous mimic. [29][30][31] In our study, the two reactions that use initiator 4 were anticipated to impart selectivity to the sensing event. To test this, we conducted experiments on three nerve agent surrogates (Figures S10-S12).…”

Supramolecular Sensing of Chemical Warfare Agents

“…Kumar and co‐workers have synthesized a fluorescent chemical probe capable of sensitively and selectively detecting toxic anions and CWAs simulant (Diethyl cyanophosphonate DCNP, a Tabun simulant) through chromogenic and fluorogenic variations (Figure 7). [54] …”

“…Kumar and co-workers have synthesized a fluorescent chemical probe capable of sensitively and selectively detecting toxic anions and CWAs simulant (Diethyl cyanophosphonate DCNP, a Tabun simulant) through chromogenic and fluorogenic variations (Figure 7). [54] Detection studies were also carried out on solid surfaces, in the gas phase and in a spiked soil sample, in order to verify the concreteness of this sensing system in real life scenarios. The authors found a limit of detection of 270 mM by using naked eyes.…”

“…(b) in gas phase (c) minimum detection limits of DCNP with 2 with naked eye and its response under UV lamp (365 nm). Adapted from reference[54] with permission from the Royal Society of Chemistry.…”

Chromo-Fluorogenic Detection of Soman and Its Simulant by Thiourea-Based Rhodamine Probe

“…A typical chromo-fluorogenic probe is usually formed by two moieties: (1) a chromo-fluorogenic reporter group, which translates the binding event into the change of color and fluorescence, mainly containing rhodamine [ 22 ], fluorescein [ 15 ], boron dipyrromethene (BODIPY) [ 16 , 17 ], azo [ 14 , 20 ], and cyanine dye [ 18 ]; (2) a selective reactive group, which provides a reactive binding site for nucleophilic attack, mainly containing hydroxyl [ 15 , 25 ], oxime [ 19 ], and amino groups [ 26 ]. Recently, thiourea has been proved to be capable of reacting with nerve agents through hydrogen-bond interaction between N-H protons of thiourea and phosphonate oxygen or hydrolyzed products [ 27 , 28 ]. It has been also proven that the reaction of thiosemicarbazide group can induce opening of the spirolactam ring in rhodamine B accompanied with color change and enhanced fluorescence [ 29 ].…”