Base-Promoted Selective Synthesis of 2<i>H</i>‑Pyranones and Tetrahydronaphthalenes via Domino Reactions

A highly efficient domino protocol has been developed for the synthesis of 6-aryl-4-(methylthio/amine-1-yl)-2-oxo-2<i>H</i>-pyran-3-carbonitriles and 4-aryl-2-(amine-1-yl)-5,6,7,8-tetrahydronaphthalene-1-carbonitriles from simple and readily available α-aroylketene dithioacetals, malononitrile, secondary amines, and cyclohexanone. This elegant domino process involved consecutive addition–elimination, intramolecular cyclization, and ring opening and closing sequences. Notably, in situ generated 2-imino-4-(methylthio/amine-1-yl)-6-aryl-2<i>H</i>-pyran-3-carbonitrile plays multiple roles in the construction of various novel polyaromatic hydrocarbons

Tetraphenylethene–2-Pyrone Conjugate: Aggregation-Induced Emission Study and Explosives Sensor

Design and synthesis of a novel tetraphenylethene–2-pyrone <b>(TPEP)</b> conjugate exhibiting donor–acceptor characteristics is reported. The localized frontier molecular orbitals (DFT studies) and the solvent polarity dependent photoluminescence characteristics directly corroborate the presence of intramolecular charge transfer character in <b>TPEP</b>. <b>TPEP</b> is poorly emissive in the solution state. In contrast, upon aggregation (THF/water mixtures), <b>TPEP</b> exhibits aggregation-induced emission enhancement. Upon aggregation, dyad <b>TPEP</b> forms a fluorescent nanoaggregate which was confirmed by transmission electron microscopy imaging studies. The luminescence nanoaggregates were elegantly exploited for selective detection of nitro aromatic compounds (NACs). It was found that nanoaggregates of <b>TPEP</b> were selectively sensing the picric acid over the other NACs. Efficiency of the quenching process was further evaluated by the Stern–Volmer equation. <b>TPEP</b>-based low-cost fluorescent test strips were developed for the selective detection of picric acid

Tetraphenylethene–2-Pyrone Conjugate: Aggregation-Induced Emission Study and Explosives Sensor

Design and synthesis of a novel tetraphenylethene–2-pyrone <b>(TPEP)</b> conjugate exhibiting donor–acceptor characteristics is reported. The localized frontier molecular orbitals (DFT studies) and the solvent polarity dependent photoluminescence characteristics directly corroborate the presence of intramolecular charge transfer character in <b>TPEP</b>. <b>TPEP</b> is poorly emissive in the solution state. In contrast, upon aggregation (THF/water mixtures), <b>TPEP</b> exhibits aggregation-induced emission enhancement. Upon aggregation, dyad <b>TPEP</b> forms a fluorescent nanoaggregate which was confirmed by transmission electron microscopy imaging studies. The luminescence nanoaggregates were elegantly exploited for selective detection of nitro aromatic compounds (NACs). It was found that nanoaggregates of <b>TPEP</b> were selectively sensing the picric acid over the other NACs. Efficiency of the quenching process was further evaluated by the Stern–Volmer equation. <b>TPEP</b>-based low-cost fluorescent test strips were developed for the selective detection of picric acid