Lead (Pb) is a heavy metal known for its adverse effects on both human health and the environment. In recent years, the industrial utilization of Pb2+ has surged, underscoring the imperative need for efficient measurement methods. In this study, a rapid and simple photochemical method was used to synthesize thioglycolic acid (TGA)-stabilized CdTe/ZnSe core-shell quantum dots (QDs). These CdTe/ZnSe QDs emit vibrant green fluorescence and exhibit remarkable quenching in the presence of Pb2+ ions. This property enables the development of an on-site on/off sensor without the necessity of additional modifications. The proposed sensor possesses an outstanding sensitivity to Pb2+, with a detection limit and linear range of 31.8 nM and 50 nM-10 µM, respectively. Importantly, the selectivity of this fluorescence-based sensor was validated by analyzing various positively and negatively charged ions. Furthermore, the developed sensor showed reliable performance against real river, agricultural, and tap water, as confirmed by Inductively Coupled Plasma (ICP) analysis. Additionally, CdTe/ZnSe QDs immobilized on glass slides were successfully employed for on-site water sample analysis, providing a versatile solution for environmental monitoring.

Mercury (Hg), a notorious heavy metal with detrimental impacts on human health and the environment, necessitates the development of precise measurement methods. This study introduces an expeditious and straightforward photochemical approach to synthesize thioglycolic acid (TGA)-stabilized CdTe/CdS/ZnS core/multi-shell quantum dots (QDs). The synthesized CdTe/CdS/ZnS QDs were comprehensively characterized using fluorescence spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FESEM), and X-Ray diffraction (XRD). XRD and EDS results confirmed the successful formation of CdTe/CdS/ZnS structure. Also, FESEM and TEM results showed that CdTe/CdS/ZnS QDs were spherical. Results showed that synthesized Exhibiting vibrant green fluorescence and notable quenching in the presence of Hg2+ ions, these QDs emerge as promising candidates for fabricating a fluorescent sensor. The proposed sensor demonstrates notable sensitivity to Hg2+, featuring a detection limit of 16.32 nM and a linear range from 20 nM to 70 nM. The sensor\'s selectivity was confirmed by analyzing various anions and cations. Moreover, when tested with tap water, river water, and agricultural samples, the sensor exhibited reliable performance, validated by Inductively Coupled Plasma (ICP) analysis. Additionally, CdTe/CdS/ZnS QDs immobilized on micro pads proved effective for on-site water sample analysis, presenting a versatile solution for environmental monitoring.

An Indane-1-one derivative 11-(1-benzyl-1H-indol-3-yl)-10,12-dihydrodiindeno[1,2-b:2\',1\'-e]-pyridine (BDP) has been synthesized by the reaction of Indan-1-one with 1-benzyl-1H-indole-3-carbaldehyde. FT-IR, 1H-NMR, 13N-NMR and Mass spectroscopic techniques has been used to confirmed the structure of BDP. The observed photophysical changes in BDP across various solvents were associated. The impact of various interactions on photophysical parameters, including Stokes shift, dipole moment, oscillator strength, and fluorescence quantum yields, has been assessed in relation to solvent polarity. Moreover, BDP demonstrates potential as a selective fluorescent chemosensor for detecting Fe3+ ion within a range of cations in an aqueous DMSO environment. A thorough investigation into the recognition mechanism of BDP towards Fe3+ ion has been conducted using Benesi-Hildebrand and Stern-Volmer, measurements. BDP forms a 2:1 complex with the Fe3+ ion, exhibiting fluorescent quenching behaviour.

In this review, we present a systematic and comprehensive summary of the recent developments in the synthetic strategies of 2-(2-hydroxyarylsubstituted)-benzothiazole (HBT) framework along with incorporation of various substituents on phenolic and benzothiazole rings which affect the emission process. The literature, spanning the years 2015-2024, on excited-state intramolecular proton transfer (ESIPT)-based studies of HBT derivatives comprising the effects of solvent polarity, substituents, and extended conjugation on fluorophores has been searched. ESIPT, intramolecular charge transfer, and aggregation-induced emissions enable these fluorescent probes to specifically interact with analytes, thereby altering their luminescence characteristics to achieve analyte detection. These fluorescent probes exhibit large Stokes shifts, high quantum yields, and excellent color transitions. Finally, the applications of HBTs as ESIPT-based fluorescent probes for the detection of cations, anions, and biomolecules have been summarized. We anticipate that this review will provide a comprehensive overview of the current state of research in this field and encourage researchers to develop novel ESIPT-based fluorophores with new applications.

Dimethylaniline-substituted aza-BODIPY dyes (DA, DM, DP) were designed and synthesized aiming for ion detection. The Zn2+ recognition ability was found in all compounds and the binding mechanism was possibly via dimethylaniline sites linked to the aza-BODIPY core. Upon Zn2+ addition, the new absorption band and the color change occurred due to the altered charge transfer of the adducts. The custom-made colorimeter was successfully integrated into the dye\'s application, demonstrating a good linear relationship between resistance values and Zn2+ concentration. The chromophore test strips were fabricated and exhibited distinct color changes upon aqueous Zn2+ exposure. The compound DA also exhibits logical behavior with DA-Zn2+-Cu2+ system. In terms of environmental hazards, the compounds exhibited no adverse effect on Pseudomonas putida at the concentration level of 0.2 mg/mL. These findings indicated that all synthesized aza-BODIPYs might be suitable for chemosensor probes for Zn2+ detection with possibly low environmental risk.

Circular dichroism (CD) based enantiomeric excess (ee) determination assays are optical alternatives to chromatographic ee determination in high-throughput screening (HTS) applications. However, the implementation of these assays requires calibration experiments using enantioenriched materials. We present a data-driven approach that circumvents the need for chiral resolution and calibration experiments for an octahedral Fe(II) complex (1) used for the ee determination of α-chiral primary amines. By computationally parameterizing the imine ligands formed in the assay conditions, a model of the circular dichroism (CD) response of the Fe(II) assembly was developed. Using this model, calibration curves were generated for four analytes and compared to experimentally generated curves. In a single-blind ee determination study, the ee values of unknown samples were determined within 9% mean absolute error, which rivals the error using experimentally generated calibration curves.

Bacillus anthracis is a causative agent of the highly mortal disease anthrax. This zoonosis is present in nature, but it is also considered one of the most powerful biological warfare agents. A timely diagnosis is necessary for proper therapy and setting of epidemiological countermeasures. Current diagnostic methods should be used in specialized laboratories or medical facilities because there are only a limited number of methods suitable as hand-held assays or even point-of-care tests for detecting B. anthracis or anthrax diagnosis. The lateral flow tests are an exception in this regard, but these tests also have some limitations. Significant progress has been achieved in point-of-care tests for B. anthracis detection and anthrax diagnosis in various biosensors and bioassays. This review focuses on current hand-held and point-of-care tests that can easily prove anthrax or its causative agent outside the context of specialized facilities.

This comprehensive review delves into the current landscape and future outlook of chemosensors constructed from polycyclic aromatic compounds (PACs) for the detection of toxic ions. PACs, known for their unique molecular properties, have emerged as key building blocks for the development of chemosensors due to their sensitivity, selectivity, and versatility. The review begins by providing an overview of the existing literature on PAC-based chemosensors, detailing their design principles, structural modifications, and mechanisms of ion recognition. The discussion encompasses various toxic ions, including heavy metals, anions, and other environmental pollutants, showcasing the broad applicability of PAC-based chemosensors in diverse analytical contexts. The review also highlights recent advancements in the field, exploring novel strategies and materials for enhancing the performance of PAC-based chemosensors. Furthermore, the review critically evaluates the current challenges and limitations associated with PAC-based chemosensors, offering insights into potential avenues for future research and technological development.

A highly selective bis thiophene-based chalcone as a chemosensor for detecting Fe3+ metal ions in DMF: H2O (9:1). This sensor was selective toward ferric ions over other metal ions with a detection limit in micromolar range.

A newly synthesized naphthalimide-based fluorophore probe NIA was used to detect hydrazine. This probe, based on the Gabriel mechanism exhibited a highly sensitive revealing of hydrazine in naked eyes colorimetric as well as fluorescent recognition against other amines in an aqueous solution in DMSO - HEPES buffer. When hydrazine hydrate was added to the probe NIA, the absorption was red shifted from 403 nm to 520 nm. The titration studies by adding hydrazine to show two apparent isosbestic points found at 358 and 450 nm, respectively. Further, investigation of emission spectra upon addition of hydrazine hydride the emission peak at 493 nm gradually decreased up to 2.4 equiv. and when increasing the hydrazine hydride concentration from 2.4 equiv. to 4.4 equiv., the fluorescence intensity increased at 530 nm. which is exhibiting a raised ratiometric emission intensity at 530 nm. Further investigation of the selectivity of probe NIA revealed colorimetric and fluorimetric responses to interferences with other test amines. 1H NMR and HR-mass proved the Gabriel mechanism bath for detecting hazardous hydrazine by probe NIA. This probe NIA allowed the rapid and ultrasensitive detection of hydrazine hydride with a low detection limit of 0.26 nM. In view of the outstanding properties, probe NIA has been effectively performed to detect hydrazine using various techniques, including a test kit, silica support, and actual environmental water samples.