A New Compound for Sequential Sensing of Picric Acid and Aliphatic Amines: Physicochemical Details and Construction of Molecular Logic Gates

Abstract

Picric acid (PA) at low concentration is a serious water pollutant. Alongside, aliphatic amines (AAs) add to the queue to pollute surface water. Plenty of reports are available to sense PA with an ultralow limit of detection (LOD). However, only a handful of works are testified to detect AAs. A new fluorescent donor-acceptor compound has been synthesized with inherent intramolecular charge transfer (ICT) character that enables selective and sensitive colorimetric quantitative detection of PA and AAs with low LODs in nonaqueous as well as aqueous solutions. The synthesized compound is based on a hemicyanine skeleton containing two pyridenylmethylamino groups at the donor and a benzothiazole moiety at the acceptor ends. The detailed mechanisms and reaction dynamics are explained spectroscopically along with computational support. The fluorescence property of the detecting compound changes due to protonation of its pyridinyl centers by PA leading to quenching of fluorescence and subsequently de-protonation by AAs to revive the signal. We have further designed logic circuits from the acquired optical responses by sequential interactions.

A metal complex based fluorescent chemodosimeter for selective detection of 2,4-dinitrophenol and picric acid in aqueous media

“…The K SV , K a and LOD values were calculated by comparing the fluorescence intensity obtained for 1 in the presence and absence of DNP/PA as reported earlier in the literature. 6–45,63 The fluorescence quenching titrations were carried out in pure water by placing 3 mL (20 μM solution) of 1 in a quartz cuvette of 1 cm path length. Then, a methanolic solution of either DNP or PA (0–2.6 equiv.)…”

“…hydrogen bonding, metal–ligand coordination, electrostatic interactions) have been taken into consideration. 6–45 As chemodosimeters are changed to drastically different species while exhibiting the sensing property, the concerned process is irreversible. 46 Nonetheless, highly selective fluorescent chemodosimeters for biologically important metal ions ( e.g.…”

“…As sensing of nitroaromatics is a field of great interest, several fluorescent chemosensors for nitroaromatics have been reported. 6–45 We have found that in only one case, the authors mentioned and explained the sensor as a fluorescent chemodosimeter. 13 The concerned compound is a small organic molecule which detects picric acid in 1 : 9 H 2 O : CH 3 CN.…”

“…In general, for mechanistic interpretation of the sensing of any analyte, single crystal structural evidence of the final association complex between the analyte and probe plays a crucial role in justifying the mechanism. In this regard, it is worth mentioning that although there are a large number of reported fluorescent chemosensors for nitroaromatics, 6–45 characterizing the sensor⋯nitroaromatic association complexes by single crystal X-ray structure determination has been possible only in some limited cases. 6–11,29–31 Notably, the single crystal X-ray structures of the sensor⋯nitroaromatic association complexes for the already mentioned fluorescent chemodosimeters have not been reported.…”

“…For practical purposes, the performance of fluorescent probes, prepared by easy synthetic methods, in aqueous media is highly desirable. A wide range of fluorescence materials based on small organic molecules, [6][7][8][9][10][11][12][13][14][15][16][17][18] organic polymers including conjugate polymers, 19,20 discrete metallo-organic coordination compounds, [21][22][23][24][25][26][27][28][29][30][31] coordination polymers including MOFs [32][33][34][35][36][37][38][39][40][41] and carbon or quantum dots [42][43][44][45] have been reported for the detection of nitro explosives. The majority of these materials are efficient in organic media and their preparation involves multistep procedures with high temperature and low yield.…”