Synthesis of 5-nitrovanillin in low temperature as cyanide anion sensor

In the synthesis of the organic sensor, the molecular structure will affect the ability of a compound to be used as a colorimetric chemosensor. Here, we present a simple synthesis technique for 5-nitrovanillin. It has been successfully synthesized using nitric acid as a source of nitro groups. Dichloromethane DCM was used as a solvent, and the synthesis was carried out at low temperatures (under 5°C). The method produces a good yield. The nitro group attached to the structure of the chemosensor plays a role in prolonging the electron delocalization. Its effect is in the process of anion recognition by the chemosensor. The formation of a sensor-analyte complex between the chemosensor and anion produces a color change in the solution.

Carbazole-Based Colorimetric Anion Sensors

Owing to their strong carbazole chromophore and fluorophore, as well as to their powerful and convergent hydrogen bond donors, 1,8-diaminocarbazoles are amongst the most attractive and synthetically versatile building blocks for the construction of anion receptors, sensors, and transporters. Aiming to develop carbazole-based colorimetric anion sensors, herein we describe the synthesis of 1,8-diaminocarbazoles substituted with strongly electron-withdrawing substituents, i.e., 3,6-dicyano and 3,6-dinitro. Both of these precursors were subsequently converted into model diamide receptors. Anion binding studies revealed that the new receptors exhibited significantly enhanced anion affinities, but also significantly increased acidities. We also found that rear substitution of 1,8-diamidocarbazole with two nitro groups shifted its absorption spectrum into the visible region and converted the receptor into a colorimetric anion sensor. The new sensor displayed vivid color and fluorescence changes upon addition of basic anions in wet dimethyl sulfoxide, but it was poorly selective; because of its enhanced acidity, the dominant receptor-anion interaction for most anions was proton transfer and, accordingly, similar changes in color were observed for all basic anions. The highly acidic and strongly binding receptors developed in this study may be applicable in organocatalysis or in pH-switchable anion transport through lipophilic membranes.

Steric Shelter-free Cobalt Nanoparticles-based High-sensitive Biomimetic Superoxide Anion Sensor

Here unique cobalt nanoparticles were deposited on nitrogen-doped graphene as an enzyme-free biomimetic sensor for superoxide anion detection with the shortest response time and the highest sensitivity among the known...

Exploring the Effects of Various Polymeric Backbones on the Performance of a Hydroxyaromatic 1,2,3-Triazole Anion Sensor

Polymeric chemosensors are vital sensing tools because of higher sensitivity compared to their monomeric counterparts and tunable mechanical properties. This study focuses on the incorporation of a hydroxyaromatic 1,2,3-triazole sensor, 2-(4-phenyl 1H-1,2,3-triazol-1-yl)phenol (PTP), into polymers. By itself, the triazole has a selective, fluorometric response to the fluoride, acetate, and dihydrogen phosphate anions, and is most responsive to fluoride. Current investigations probe the suitability of various polymeric backbones for the retention and enhancement of the triazole’s sensing capabilities. Backbones derived from acrylic acid, methyl methacrylate, divinylbenzene, and styrene were explored. UV-illumination, Nuclear Magnetic Resonance (NMR) titration, and ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy studies are used to investigate the performance of newly synthesized polymers and the derivatives of PTP that serve as the polymers’ precursors. Among the polymers investigated, copolymers with styrene proved best; these systems retained the sensing capabilities and were amenable to tuning for sensitivity.

Methyl-3-(2-hidroxy-5-nitrophenyl amino)-3-phenylpropanoate Based Colorimetric Sensor for Oxyanions

A colorimetric anion sensor of methyl-3-(2-hydroxy-5-nitrophenyl amino)-3-phenylpropanoate bearing –OH and –NH groups as binding sites and nitrophenyl as a signaling unit, has been successfully accomplished. The compound functioned as a colorimetric chemosensor for H2PO4– and AcO–, in particular, the sensor showed significant naked-eye detectable color change from colorless to light yellow. In contrast, no color change was detected upon addition of other anions such as SO42–, NO3–, and CIO4–. The anion sensing ability of the sensor was further investigated by UV-Vis absorption spectroscopy in acetone. Characteristic UV-Vis spectra changes were revealed upon addition of H2PO4– and AcO–.

Senyawa Hidrazone dari Vanilin-DNPH Sebagai Sensor Kolorimetri Anion Sianida

<p>Senyawa hidrazon (<em>E</em>)-4-((2-(2,4-<em>dinitrophenyl</em>)<em>hydrazineylidene</em>)<em>methyl</em>)-2-<em>methoxyphenol</em> telah disintesis dari vanilin dan 2,4-dinitrofenilhidrazin (DNPH). Uji sensor anion dilakukan dengan menambahkan anion F^-, Cl^-, Br^-, I^-, CN^-, SO₄^2-, CO₃^2-, CH₃COO^- dan H₂PO₄^- dalam pelarut asetonitril. Uji limit deteksi reseptor (<em>E</em>)-4-((2-(2,4-<em>dinitrophenyl</em>)<em>hydrazineylidene</em>)<em>methyl</em>)-2-<em>methoxyphenol</em> terhadap anion sianida dilakukan dalam pelarut asetonitril. Hasil uji sensor anion menunjukan bahwa reseptor selektif terhadap anion sianida dengan menghasilkan perubahan warna dari kuning ke merah. Hasil analisa dengan spektrofotometer UV-Vis reseptor memberikan perubahan panjang gelombang dari 395 nm menjadi 472 nm pada penambahan anion sianida. Reseptor (<em>E</em>)-4-((2-(2,4-<em>dinitrophenyl</em>)<em>hydrazineylidene</em>)<em>methyl</em>)-2-<em>methoxyphenol</em> dapat mendeteksi anion CN- dengan limit deteksi sebesar 7 mM.</p><p> </p><p><strong>A Hydrazone Compound from Vanillin-DNPH as Colorimetric Sensor of Cyanide Anion</strong><strong>.</strong> A hydrazone compound (<em>E</em>)-4-((2-(2,4-dinitrophenyl)hydrazineylidene)methyl)-2-methoxyphenol has been synthesized from vanillin and 2,4-dinitrophenylhydrazine (DNPH). The anion sensor study were done by adding Br^-_,CN^-, F^-, SO₄^2-_,Cl^-, I^- , CO₃^2-, CH₃COO^- and H₂PO₄^- anion in acetonitrile solvent. The detection limit study of receptor <em>E</em>)-4-((2-(2,4-dinitrophenyl)hydrazineylidene)methyl)-2-methoxyphenol for cyanide anion was carried out in acetonitrile. The result of anion sensor study shows that the receptor was selective to cyanide anion by providing change of color from yellow to red. The analysis result using spectrophotometer ultraviolet-visible of the receptor provided change of maximum wavelength from 395 nm to 472 nm when the cyanide anion was added. Receptor (<em>E</em>)-4-((2-(2,4-dinitrophenyl) hydrazineylidene)methyl)-2-methoxyphenol can detect CN^- with limit of detection 7 mM.</p><div><span><br /></span></div>