Haloarene-Linked Unsymmetrically Substituted Triarylethenes: Small AIEgens To Detect Nitroaromatics and Volatile Organic Compounds.

Unsymmetrically substituted triarylalkenes as aggregation-induced emission-active fluorogens (AIEgens) are sporadically explored by different researchers. In this Article, naphthalene, biphenyl, and haloarene-linked new triarylethenes are conveniently synthesized and presented as unsymmetrically substituted extensive π-conjugates to continue the discovery of small molecules as new AIEgens. Moreover, fluorophores attached to haloarenes are noteworthy, but such compounds are barely investigated as AIEgens. The possible mechanism underlying this AIE-behavior has also been addressed by the support of experimental/theoretical outcomes. Moreover, two of these small AIEgens are fruitfully employed for rapid sensing of nitroaromatic compounds (NACs) where picric acid (PA, as a model explosive) showed a strong quenching efficiency with the detection limit of 39 or 48 ppb along with other nitroaromatics such as p-nitrotoluene and p-nitrophenol. This quenching could be visualized by the naked eye under a UV (365 nm) lamp and performed almost in an aqueous medium. Such alkenes are also proved to exhibit very clean on/off fluorescence switching properties for polar volatile organic compounds (VOCs).