Recent endeavours in the development of organo chromo-fluorogenic probes towards the targeted detection of the toxic industrial pollutants Cu2+ and CN−: recognition to implementation in sensory device

Abstract

Copper is an indispensable transition element owing to its significant physiological activities. However, the unregulated excess of this biologically ubiquitous ion can induce severe neurodegenerative diseases. Likewise, among the anions, cyanide is recognized as a potent health hazard owing to its extensive industrial applications and it is the most toxic ion known. Therefore, presently, the extensive and inappropriate use of copper- and cyanide-containing materials in industry, domestically, agriculture and diverse sectors have caused increasing environmental concern owing to the copper- or cyanide-induced pollution of biotic and abiotic systems. This has prompted researchers to focus on the development of proficient chromo-fluorogenic (optical) molecular probes for the effective and ultrasensitive detection of these lethal industrial pollutants. Considering this, in the present review, we systematically summarize the literature reports in the last decade (2013–2022) based on organo chromo-fluorogenic sensory receptors towards the effective ultrasensitive detection of Cu²⁺ and CN⁻. For readers to gain a detailed understanding, sensory receptors are comprehensively described based on their underlying recognition mechanisms and their imperative advancement in the field of supramolecular chemistry. The chemo mechanistic pathway of the host:guest interaction is elaborately and schematically explained by highlighting the intramolecular charge transfer (ICT), photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), aggregation-induced emission (AIE), chelation-enhanced fluorescence (CHEF), CN isomerization, excited-state intramolecular proton transfer (ESIPT), deprotonation, H-bonding interaction, nucleophilic attack and metal displacement mechanisms. The practical applications of these chemoreceptors in daily life are reviewed herein, and their future outlook is briefly discussed to build a complete library of information regarding their practical applicability in the multidimensional supramolecular functional field of sensing. Furthermore, the appropriate synchronization of chemical response with molecular electronic circuitry via the fabrication of “easy-instant-economic-portable” sensory prototypes involving the exquisite integration of RGB-OLED-IoT under one umbrella combined with artificial intelligence will contribute to contemporary chemical expertise towards instantaneous and real-time monitoring of targeted analytes. We envision that this review focusing on supramolecular application will provide an impetus towards exploring novel unprecedented concepts for designing and synthesizing promising colorimetric and/or fluorometric chemoreceptors with improved photophysical responses and enhanced efficiency for real-time point-of-care analyses.