Gallium(III) selective sensors based on 2-amino-3-(α-N-phenylmethyl-2′-amino-1′,4′-naphthoquinonyl)-1,4 naphthoquinones in poly (vinyl chloride)

A highly selective "turn-on" water-soluble fluorescent sensor for gallium ion detection

In this work, a novel sensor, (E)-N′-(3-(tert-butyl)-2-hydroxybenzylidene)thiophene-2-carbohydrazide (1), based on salicylaldehyde and thiophene hydrazide moieties was designed and synthesized. The single-crystal structure of 1 was achieved and studied for understanding its functional properties. The interaction and recognition abilities of 1 with different metal ions were investigated. Sensor 1 showed excellent “turn-on” fluorescence with highly selective and specific recognition ability in the presence of gallium ions (Ga³⁺) in an aqueous solution. The sensing behavior of 1 with Ga³⁺ was also studied by photophysical experiments, ESI-MS analysis, and ¹H NMR titration. The limit of detection (LOD) and limit of quantification (LOQ) of 1 for the detection of Ga³⁺ in an aqueous solution were calculated as 58 nM, and 192 nM, respectively. DFT calculations were carried out to optimize the configuration of 1 and 1–Ga³⁺ complexes and rationalize the photophysical experimental data. Highly selective test strips based on sensor 1 were developed for Ga³⁺ detection. Sensor 1 was also used to detect Ga³⁺ in actual water samples, and a considerable recovery rate was obtained.

In this work, a highly selective water-soluble “turn-on” fluorescent sensor for gallium ion recognition was reported.

A Thiourea-Containing Fluorescent Chemosensor for Detecting Ga3

A thiourea-based fluorescent chemosensor NADA, (E)-2-(4-(diethylamino)-2-hydroxybenzylidene)-N-(naphthalen-1-yl)hydrazine-1-carbothioamide, has been designed and synthesized. NADA could detect Ga³⁺ through a fluorescent turn-on with a low detection limit (0.29 μM). Importantly, NADA could effectively discriminate Ga³⁺ from Al³⁺ and In³⁺. The binding mechanism of NADA with Ga³⁺ was identified by ESI-mass, NMR titration, and DFT calculations.

A dual target chemosensor for the fluorometric detection of In3+ and colorimetric detection of Fe3

A new dual target chemosensor 1, 1,1'‑((1E,1'E)‑((thiobis(ethane‑2,1‑diyl))bis(azanylylidene))bis(methanylylidene))bis(naphthalen‑2‑ol), was prepared by the reaction of a hydroxy-naphthaldehyde and a thiobis(ethylamine). Sensor 1 detected In³⁺ with turn-on fluorescence and Fe³⁺ via the change of color from colorless to pale violet. The sensing behaviors of 1 toward In³⁺ and Fe³⁺ were studied through photophysical experiments, ESI-mass, NMR titration, and theoretical calculations. In particular, 1 can discriminate In³⁺ from Al³⁺ and Fe³⁺ from Fe²⁺. Limits of detection for the analysis of In³⁺ and Fe³⁺ ions turned out to be 5.89 μM and 0.30 μM, respectively. In addition, sensor 1 functioned practically as a naked-eye test strip for Fe³⁺ and could be recycled by using EDTA for In³⁺ and DFO for Fe³⁺.

Electrochemical Analysis of Some Toxic Metals by Ion-Selective Electrodes

An overview of potentiometric sensors that are capable of detecting toxic heavy metal ions in environmental samples is presented and discussed. Notwithstanding the tremendous work performed so far, it is obvious that still several limitations do exist in terms of selectivity, limits of detection, dynamic ranges, applicability to specific problems, and reversibility. A survey on important advances in potentiometric sensors with regard to high selectivity, lower detection limit, fast response time, and on-line environmental analysis is presented in this review article. [Supplemental materials are available for this article. Go to the publisher's online edition of Critical Reviews in Analytical Chemistry to view the free supplemental file.].