Hydrogen bond directed high-fidelity optical detection of picric acid: A single driver on diverse roads towards the same destiny

Abstract

High-fidelity optical detection of picric acid (PA) is necessary due to its toxic and explosive nature. Moreover, PA is a molecule with versatile features, such as hydrogen bond or proton donor–acceptor centers, extremely low pK_a, highly electron-deficient center, high water solubility, etc. These unique features and concerns stimulated us to write this review article on the small-molecule-based optical detection of PA. This article describes the hydrogen bonding triggered optical detection of PA chronologically and categorically, with a particular focus on the development of small-molecule-based fluorophores reported over the last two decades. Special attention is conferred on how the single driver, hydrogen bonding, can bring about distinct and dissimilar phenomenal changes (such as aggregation, chelation, charge transfer, electron transfer, proton transfer, energy transfer, excimer formation, etc.) on the variation of the signaling and/or the binding unit of the probe molecules upon interaction with PA to reach the single destiny of the optical detection of the explosive. Finally, conclusions are made on the key points and achievements of the optical detection of PA along with the existing potential challenges for young researchers who will develop innovations in this field. We believe that the article will be an important addition to the existing literature on PA sensing.