AIE-active phenothiazine based Schiff-base for the selective sensing of the explosive picric acid in real water samples and paper-based device

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2023-01, Vol.434, p.114224, Article 114224
• Main Authors: Barot, Yash B., Anand, Vivek, Mishra, Roli
• Format: Article
• Language: English
• Subjects: AIEE; Explosives; Nitroaromatic compounds; Paper Sensor; Picric acid; Schiff base
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2022.114224

[Display omitted] •Di-Phenothiazine based Schiff base (DPTZ-SB) was synthesized using facile methods.•DPTZ-SB showed AIEE properties with a 9.4-fold increase in fluorescence intensity for 10:90 DMF/water mixture.•A novel fluorescent paper sensor was developed based on DPTZ-SB.•The paper sensor is stable, recyclable, and cost-effective.•The DPTZ-SB recognized PA with a limit of detection of 0.2 ppb and 0.04 ppb in solution and paper sensor, respectively. A highly selective and sensitive AIE fluorescent chemosensor based on phenothiazine and ethylene diamine was synthesized (DPTZ-SB) for the exclusive detection of picric acid (PA). Interestingly, DPTZ-SB can sense PA exclusively over five other competitive explosives, due to the specific complexation ability of DPTZ-SB towards PA. For the better mechanistic understanding, Stern-Volmer, Modified Stern-Volmer and Job’s plot were employed, which showed the limit of detection and binding constant to be 0.2 ppb and 4.05 × 1010 M−1, respectively, and the stoichiometric ratio of DPTZ-SB:PA as 1:2. The values are promising as compared to the AIE fluorophores reported for PA sensing recently. The sensing mechanism was elucidated using DFT studies and 1H NMR titration experiment, which revealed the active involvement of the imine groups of the Schiff base in the complexation process. Furthermore, in order to broaden the applicability, the probe DPTZ-SB was applied in real water samples obtained from the local river, lake and tap water. Interestingly, a paper based fluorescent sensor was devised by embedding DPTZ-SB on the filter paper and was analyzed by a handheld UV lamp. Under UV light illumination, the paper-based sensor exhibited prominent fluorescence quenching in the presence of PA, which can be conveniently visualized. Moreover, the color-scanning application available in smart phones was coupled with the paper-based sensor to quantitate the scanometric assays. On a parallel note, DPTZ-SB showed excellent aggregation induced enhanced emission (AIEE) property. In fact, a 9.4-times enhancement in the photoluminescence (PL) intensity was noted for a 90:10 H2O:DMF of DPTZ-SB as compared to that in pure DMF. Therefore, the multifaceted applicability of the Schiff base has been explored, particularly in the fields of PA explosive detection device in real life samples and AIEE.