Development of dual chemosensor is drawing special attention of the researchers because of its several advantages over chemosensors for a single analyte. A dual chemosensor for two cations can save time and cost in contrast to preparation of two different chemosensors for sensing of each of those cations. Thus, a number of dual chemosensors for different combinations of two cations have been reported recently. So, compilation of so far published pure organic compounds as dual chemosensors is highly beneficial in order to build a library of these chemosensors to get ready information about this field. Detection type, detection limit, association constant with coordination binding mode, excitation and emission wavelengths and media of the spectroscopic measurements have been discussed. Over 275 articles are included in this comprehensive review paper.

Dual chemosensors for metal ions: A comprehensive review

An organic molecule-based sensor 4-((4-(dimethylamino)phenyl)diazenyl)-N-(quinolin-8-yl)benzenesulfonamide(MASP)able to detect multiple analytes such as moisture, warfare reagent (phosgene), divalent (Cu2+), and trivalent (Fe3+) has been reported. These analytes belong to the different classes of chemicals and barely interfere in the real sample. Fluorescence emission of MASP was observed due to the ESIPT mechanism, but it was inhibited by water. This phenomenon was utilized for moisture detection in DMSO and THF with the detection limit of 0.0032 % w/w and 0.0014 % w/w, respectively. The MASP was also employed for the colorimetric sensing (yellow to red) of phosgene in solution and gas with good selectivity and high sensitivity (LOD = 23 nM). The naked eye detection of MASP was incorporated with RGB color value to make use of MASP for the practical application using a smartphone as a portable analytical device. The distinct color change of divalent Cu2+ (yellow to colorless) and trivalent Fe3+ (yellow to red) observed with MASP also helps discriminate Cu2+ and Fe3+ among various cations.

Multianalytes Sensing Probe: Fluorescent Moisture Detection, Smartphone Assisted Colorimetric Phosgene recognition and Colorimetric Discrimination of Cu2+and Fe3+ ions

A simple Schiff base fluorescent probe (SW) composed of oxime and salicylaldehyde units was designed and synthesized. The probe has high selectivity and sensitivity for Zn2+ ion in mixed solvent (DMSO/H2O, V/V = 9:1). The fluorescence has obvious redshift phenomenon and visible color change. The stoichiometric ratio of the probe to Zn2+ ion was confirmed to be 1:2 (mole) by 1H NMR, MS analysis and job curves. And the detection limit of fluorescence response of the SW to Zn2+ is down to 2.53 × 10–8 mol/L. At the same time, the probe SW can be applied to the test paper detection of Zn2+ ions under 365 nm UV light and the detection of Zn2+ ions in actual water samples.

A high selective “turn-on” fluorescent chemosensor for detection of Zn 2+ in aqueous media

Electrochemical nitrate (NO3-) reduction is a potential approach to produce high-value ammonia (NH3) while removing NO3- pollution, but it requires electrocatalysts with high efficiency and selectivity. Herein, we report the development of Fe3O4 nanoparticles decorated TiO2 nanoribbon array on titanium plate (Fe3O4@TiO2/TP) as an efficient electrocatalyst for NO3--to-NH3 conversion. When operated in 0.1 M phosphate-buffered saline and 0.1 M NO3-, such Fe3O4@TiO2/TP achieves a prominent NH3 yield of 12394.3 μg h-1 cm-2 and a high Faradaic efficiency of 88.4%. In addition, it exhibits excellent stability during long-time electrolysis.

Ambient Ammonia Synthesis via Nitrate Electroreduction in Neutral Media on Fe3O4 Nanoparticles-decorated TiO2 Nanoribbon Array.

Substituent effects on photophysical properties of ESIPT-based fluorophores bearing the 4-diethylaminosalicylaldehyde core

Zinc-air battery-based desalination (ZABD) is a potential solution to effectively desalinate brackish water and supply energy simultaneously, which requires catalysts with high and durable electrocatalytic activity for oxygen reduction reaction...

Co/Fe3O4 Nanoparticles Embedded in N-doped Hierarchical Porous Carbon Derived from Zeolitic Imidazolate Frameworks as Efficient Oxygen Reduction Electrocatalysts for Zinc-Air Battery-based Desalination

Defect Engineering in g-C_3N_4 Quantum-Dot-Modified TiO_2 Nanofiber: Uncovering Novel Mechanisms for the Degradation of Tetracycline in Coexistence with Cu^2+

A readily available 4-diethylaminosalicylaldazine-modified fluorene Schiff base (EASA-F) was designed and synthesized through a one-step reaction. EASA-F exhibited a fast fluorescence OFF–ON response to Zn2+ and an OFF–ON–OFF behavior to Fe3+ in aqueous acetonitrile. This was synchronously accompanied by diverse absorption-ratiometric changes and colorimetric changes that were observable by the naked eye; these changes were attributed to the inhibition of CN isomerization and ESIPT processes in addition to the ICT mechanism that resulted from the different binding modes between the enol–keto species and Zn2+/Fe3+. Moreover, the multi-optical responses of EASA-F to Zn2+/Fe3+ were reversible with EDTA as the chelating ligand. These findings combined with the dual-optical changes from the metal displacement of EASA-F–Zn2+ by Fe3+ make the single-molecule EASA-F a real-time versatile sensor for sensitively detecting Zn2+ and accurately quantifying Fe3+.

Jingzhe Zhang

Papers

Co/Fe3O4 Nanoparticles Embedded in N-doped Hierarchical Porous Carbon Derived from Zeolitic Imidazolate Frameworks as Efficient Oxygen Reduction Electrocatalysts for Zinc-Air Battery-based Desalination

Defect Engineering in g-C_3N_4 Quantum-Dot-Modified TiO_2 Nanofiber: Uncovering Novel Mechanisms for the Degradation of Tetracycline in Coexistence with Cu^2+

An easy-to-synthesize multi-photoresponse smart sensor for rapidly detecting Zn2+ and quantifying Fe3+ based on the enol/keto binding mode

Plasma boosted the conversion of waste plastics into liquid fuel by a peroxymonosulfate-hydrothermal process

Role of solvent in plasma-assisted peroxymonosulfate-hydrothermal process for plastic conversion.