8‐Hydroxyquinoline Fluorophore for Sensing of Metal Ions and Anions

Abstract

Among various known hydroxyquinolines, 8-hydroxyquinoline (8-HQ) is the most prevalent moiety due to excellent property for the formation of the complex with different metal ions and anions, and utilized in a wide variety of applications in pharmacological and medicinal fields. 8-Hydroxyquinoline moiety and its analogues acts as fluorophoric ligands on complex formation with alkali and alkaline as well as transition metal ions and anions, thus, considered as an ideal building block in metallo-supramolecular chemistry for recognition, separation, and quantitative investigation of cations. 8-Hydroxyquinoline moiety is also used in various applications for the advancement of novel fluorescent chemosensors in a wide variety of areas viz., material chemistry, bioorganic chemistry, molecular imaging, analytical chemistry, molecular recognition, medical and biological science communities. The present review emphasises on the progress of sensing properties of 8-HQ centred small-molecule fluorescent chemosensors towards several metal ions viz.

Application of Optical Hydrogels in Environmental Sensing

“…[110] Interestingly, 8-HQ, described in Section 2, is weakly fluorescent, and complexes between 8-HQ and metal ions can enhance the fluorescence by blocking the ESIPT channel. [111] Therefore, PCHs with 8-HQ as an acceptor could detect metal ions more sensitively with the assistance of a fluorescence enhancement system (Figure 11i). Different metal ions could also be identified owing to their ESIPT-blocking ability.…”

Application of optical hydrogels in environmental sensing

“…However, this hydrolysis caused a sol reaction, which was detrimental to the stability of the CFHs [110] . Interestingly, 8-HQ, described in Section 2 , is weakly fluorescent, and complexes between 8-HQ and metal ions can enhance the fluorescence by blocking the ESIPT channel [111] . Therefore, PCHs with 8-HQ as an acceptor could detect metal ions more sensitively with the assistance of a fluorescence enhancement system (Figure 9i ) .…”

The Simple Synthesis of High Metal Loading Single-Atom Catalysts via Chelate Fixation

“…In order to retard (or eliminate) the negative influence of such water on the formation of supported single atoms, a chelating agent was introduced immediately following the precursor adsorption step. This chelating agent, 8-hydroxyquinoline (8-HQ), has a high affinity for transition metals (41)(42)(43)(44), and has been shown to adsorb on a variety of oxide and carbon surfaces for applications in metal extraction (45)(46)(47). We surmised that 8-HQ, which is not soluble in water, will isolate the metal precursor on the support surface without the need for defects or anchoring sites (Fig.…”