Design, Synthesis and Application of 1,4-disubstituted 1,2,3-triazole Based Chemosensors: A Promising Avenue

The 1,2,3-triazole-based chemosensors, synthesized through Cu(I)-catalyzed azide-alkyne cycloaddition via 'click chemistry', offer a straightforward yet highly effective method for detecting metal cations and anions with remarkable accuracy, selectivity and sensitivity, making them invaluable across various fields such as chemistry, pharmacology, environmental science and biology. The selective recognition of these ions is crucial due to their significant roles in biological and physiological processes, where even slight concentration variations can have major consequences. The article reviews literature from 2017 to 2024, highlighting advancements in the synthesis of 1,2,3-triazole-based ligands and their application (along with sensing mechanism) for detection of various ions causing health and environmental hazards. The detection aspects have been discussed sequentially for the transition-, inner transition-, and the metals from the s or p block of the periodic table.

Naphthalimide-based new architecture for fluorescence turn-on sensing of Cu2+ and colorimetric detection of F-/CN. Methods 2024;225:13-19. [PMID: 38438060 DOI: 10.1016/j.ymeth.2024.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

A new molecular structure 1 has been developed on naphthalimide motif. The amine and triazole binding groups have been employed at the 4-position of naphthalimide to explore the sensing behavior of molecule 1. Single crystal x-ray diffraction and other spectroscopic techniques confirm the identity of 1. Compound 1 exhibits high selectivity and sensitivity for Cu2+ ions in CH3CN. The binding of Cu2+ shows ∼ 70-fold enhancement in emission at 520 nm. The binding follows 1:1 interaction and the detection limit is determined to be 6.49 × 10-7 M. The amine-triazole binding site in 1 also corroborates the detection of F- through a colour change in CH3CN. Initially H-bonding and then deprotonation of amine -NH- in the presence of F- are the sequential steps involved in F- recognition with a detection limit of 4.13 × 10-7 M. Compound 1 is also sensible to CN- like F- ion and they are distinguished by Fe3+ ion. Cu2+-ensemble of 1 fluorimetrically recognizes F- among the tested anions and vice-versa. The collaborative effect of amine and triazole motifs in the binding of both Cu2+ and F-/CN- has been explained by DFT calculation.

Chromone-Based Cd(II) Fluorescent Coordination Polymer Fabricated to Study Optoelectronic and Explosive Sensing Properties

Here, electrical conductivity and explosive sensing properties of multifunctional chromone-Cd(II)-based coordination polymers (CPs) (1-4) have been explored. The presence of different pseudohalide linkers, thiocyanate ions, and dicyanamide ions resulted in 1D and 3D architecture in the CPs. Thin film devices developed from CPs 1-4 (complex-based Schottky devices, CSD1, CSD2, CSD3, and CSD4, respectively) showed semiconductor behavior. Their conductivity values increased under photo illumination (1.37 × 10-5, 1.85 × 10-5, 1.61 × 10-5, and 2.01 × 10-5 S m-1 under dark conditions and 5.06 × 10-5, 8.78 × 10-5, 7.26 × 10-5, and 10.21 × 10-5 S m-1 under light). The nature of the I-V plots of these thin film devices under light irradiation and dark are nonlinear rectifying, which has been observed in Schottky barrier diodes (SBDs). All four CPs (1-4) exhibited highly selective fluorescence quenching-based sensing properties toward well-known explosives, 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol (TNP). The limit of detection (LOD) values are 55, 28, 27, and 31 μM for TNP and 78, 44, 32, and 41 μM for DNP for complexes 1-4, respectively. A structure property correlation has been established to explain optoelectronic and explosive sensing properties.

Sensing of picric acid using an AIEE active "Turn Off" fluorescent probe derived from hydroxy naphthaldehyde and benzyloxy benzaldehyde

A novel Schiff base with AIEE characteristics has been developed and used as a chemosensor for picric acid in aqueous media. The Schiff base 1-((E)-((E)-(4-(benzyloxy) benzylidene) hydrazono) methyl) naphthalen-2-ol [BBHN] with strong fluorescence emission was obtained by the simple condensation of 1-(hydrazonomethyl)naphthan-2-ol and 4-benzoxy benzaldehyde. The characterization of BBHN was done using Fourier Transfer Infra-Red, UV-visible, Magnetic Resonance (1H and 13C) spectroscopy, and HRMS. The sensing behaviour of BBHN aggregates towards nitro explosive was then investigated. The aggregates of BBHN showed a quick, highly selective, and sensitive fluorescence 'Turn Off' response towards picric acid (PA) in an aqueous medium among various other nitroaromatics. The limit of detection was 4.04 µM with 2.03 × 106 M-1 as the quenching constant. The fluorescence "Turn Off" response in the presence of PA is mainly due to π-π interactions, and non-covalent hydrogen bonding interactions. Moreover, steady-state fluorescence lifetime measurement and Stern - Volmer plots reveal that the fluorescence quenching followed mixed quenching strategies.

A novel highly sensitive dual-channel chemical sensor for sequential recognition of Cu2+ and CN− in aqueous media and its bioimaging applications in living cells

A simple and unique dual-channel chemical probe (DH) was designed and synthesized, which not only realized sequential recognition of Cu2+ and CN− by colorimetric and fluorometric methods, but also realized fluorescence detection of CN−.