Fluorimetric and colorimetric detection of multianalytes Zn2+/Cd2+/F− ions via 5-bromosalicyl hydrazone appended pyrazole receptor; live cell imaging analysis in HeLa cells and zebra fish embryos

Organoplatinum Complex Exhibiting Aggregation-Enhanced Emission (AEE) and Dual-Channel Ion-Sensing Properties by Terminating the Molecular Configuration Transformation (MCT) and Excited-State Intramolecular Proton Transfer (ESIPT)

Emitters produce weak emissions when they undergo structural changes such as molecular configuration transformation (MCT) or excited-state intramolecular proton transfer (ESIPT) but give out strong emissions after terminating these distortions. Herein, an organoplatinum complex, Pt-ppy-ABP, carrying a salicylaldehyde-based Schiff base unit is synthesized. It exhibits weak emission in dilute solutions but shows bright emission at the aggregated state or after interacting with F- and Zn2+. This suggests that it has an aggregation-enhanced emission (AEE) property and holds potential in ion detection. Supported by theoretical calculations and femtosecond transient absorption results, this complex suffers excited-state structural changes including MCT from a square-planar configuration to a tetrahedral one, as well as intramolecular rotation of a monodentate ligand and ESIPT, showing weak emission in its solutions. At the aggregated state, it releases strong yellow emissions because of the restraints of MCT and ligand rotation. Upon interacting with F- or Zn2+, it emits bright-red or -green emissions, achieving detection limits of 10-7 M. The sensing mechanism is concluded as deprotonation- and coordination-induced ESIPT terminations, respectively. Given its AEE property and ion-responsive emissions, its application in information encryption is also explored. Finally, these findings should provide valuable clues for the developments of chemosensors with dual-channel recognition abilities.

Recent Advancements in Fluorometric and Colorimetric Detection of Cd2+ Using Organic Chemosensors: A Review (2019-2024)

In recent decades, heavy metal ions have emerged as a significant global environmental concern, posing threats to the delicate balance of ecosystems worldwide. Their introduction into ecosystems occurs through various activities and poses a serious risk to human health. Among heavy metal ions, Cd2+ is recognized as a highly toxic pollutant. Its widespread use contributes to its accumulation in the environment. Chronic exposure to Cd2+ ions present serious risks to both the environment and human health. Therefore, the detection of these metal ions are very important. Organic fluorometric and colorimetric detection have emerged as promising tools for this purpose, offering advantages such as high sensitivity, selectivity, and sometimes reversibility. This review offers a comprehensive overview of the recent advancements in the fluorometric and colorimetric detection of Cd2+ using organic chemosensors from 2019 to 2024. We delve into key aspects of these studies, including the design strategies employed to design novel chemosensors and the underlying sensing mechanisms. Furthermore, we explore the diverse applications of these organic chemosensors, ranging from environmental monitoring to biomedical diagnostics. By analyzing the latest research findings, this review aims to offer insights into the current state-of-the-art in the field of Cd2+ detection using organic chemosensors. Additionally, it highlights the potential opportunities and challenges that lie ahead, paving the way for future advancements in this important area of research.

Recent Progress on Fluorescent Probes in Heavy Metal Determinations for Food Safety: A Review

One of the main challenges faced in food safety is the accumulation of toxic heavy metals from environmental sources, which can sequentially endanger human health when they are consumed. It is invaluable to establish a practical assay for the determination of heavy metals for food safety. Among the current detection methods, technology based on fluorescent probes, with the advantages of sensitivity, convenience, accuracy, cost, and reliability, has recently shown pluralistic applications in the food industry, which is significant to ensure food safety. Hence, this review systematically presents the recent progress on novel fluorescent probes in determining heavy metals for food safety over the past five years, according to fluorophores and newly emerging sensing cores, which could contribute to broadening the prospects of fluorescent materials and establishing more practical assays for heavy metal determinations.

A dicyanisophorone-based probe for dual sensing Zn2+ and Cd2+ by near-infrared fluorescence

Zinc ions (Zn²⁺) and cadmium ions (Cd²⁺) are widely present in our production and life, which are closely related to human health and environmental protection. Hence, it is essential to detect their concentrations. Herein, we developed a convenient and reliable small-molecule fluorescent probe based on Schiff base of dicyanisophorone and 2-hydrazinopyridine. This probe can be able to selectively detect Zn²⁺ and Cd²⁺, showing the advantages of near-infrared emission (the maximum emission wavelength: 668 nm), good selectivity, high sensitivity (the detection limits: 0.21 µM and 0.31 µM, respectively) and rapid response (15 s). It has excellent potential for rapid testing and visual tracking of Zn²⁺ and Cd²⁺ in aqueous solution and living cells.

A new 5-bromoindolehydrazone anchored diiodosalicylaldehyde derivative as efficient fluoro and chromophore for selective and sensitive detection of tryptamine and F- ions: Applications in live cell imaging

A novel indole hydrazone tagged moiety, 2-((5-bromo-1H-indol-2-yl) methylene) hydrazono) methyl)-4, 6-diiodophenol (BHDL) has been developed for the selective and sensitive detection of biogenic tryptamine and F^- ions. The binding dexterity of probe BHDL towards F^-/tryptamine (TryptA) has been investigated by UV-visible/fluorescence spectroscopy. In the presence of TryptA, probe exhibits strong enhancement in the emission band at 433 nm and the band at 555 nm underwent a blue shift accompanied by a decrease in intensity by the inhibition of Excited State Intramolecular Proton Transfer (ESIPT) on BHDL. Excitingly, complexation with F^- ions as well triggers an enhancement in a fluorescence band at 430 nm with the concomitant disappearance of the emission band at 555 nm due to the inhibition of ESIPT and deprotonation process initiated by the hydrogen bonding complex formation. Further, Density Functional Theoretical (DFT) calculations have been performed to support the mechanism functioned on the probe BHDL in the presence of TryptA/F^-.