scholarly journals Styrene and Azo-Styrene Based Colorimetric Sensors for Highly Selective Detection of Cyanide

2017 ◽  
Vol 17 (2) ◽  
pp. 238
Author(s):  
Agustina Eka Prestiani ◽  
Bambang Purwono
Keyword(s):  
Color Change ◽  
Knoevenagel Condensation ◽  
Condensation Reaction ◽  
Aqueous Media ◽  
Colour Change ◽  
High Sensitivity ◽  
Colorimetric Sensing ◽  
Sensitivity And Selectivity ◽  
One Step ◽  
Knoevenagel Condensation Reaction

A novel styrene (1) and azo-styrene (2) based chemosensor from vanillin has been successfully synthesized. Sensor 1 was obtained by one step Knoevenagel condensation of Ultrasound method and sensor 2 by coupling diazo and Knoevenagel condensation reaction. Both of sensors showed high sensitivity and selectivity to detect CN- in aqueous media, even the presence of other anions, such as F-, Cl-, Br-, I-, CO32-, SO42-, H2PO4-, and AcO-. Colorimetric sensing of sensor 1 is inclined to be deprotonating of sensor binding site in the presence of cyanide and consequently improve the selectivity and sensitivity in sensing cyanide which displayed color change of sensor from yellowness to red-purple and then purple in 1 min. Sensor 2 exhibited chemodosimeter phenomenon which is caused by the nucleophilic addition of cyanide with a colour change from green to greenish-blue. The results enable to do an anion detection by a naked eye.

scholarly journals A Simple Turn-off Schiff Base Fluorescent Sensor for Copper (II) Ion and Its Application in Water Analysis

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1233
Author(s):  
Xing Zhang ◽  
Ling-Yi Shen ◽  
Qi-Long Zhang ◽  
Xian-Jiong Yang ◽  
Ya-Li Huang ◽  
...  
Keyword(s):  
Schiff Base ◽  
Fluorescent Probe ◽  
Fluorescent Sensor ◽  
Tap Water ◽  
Condensation Reaction ◽  
Aqueous Media ◽  
Sensitivity And Selectivity ◽  
One Step ◽  
Fluorescence Titrations ◽  
Nmr Titrations

An aniline-functionalized naphthalene dialdehyde Schiff base fluorescent probe L with aggregation-induced enhanced emission (AIEE) characteristics was synthesized via a simple one-step condensation reaction and exhibited excellent sensitivity and selectivity towards copper(II) ions in aqueous media with a fluorescence “ turn-off ” phenomenon. The detection limit of the probe is 1.64 × 10−8 mol·L−1. Furthermore, according to the results of the UV-vis/fluorescence titrations, Job’s plot method and 1H-NMR titrations, a 1:2 stoichiometry was identified. The binding constant between L and Cu2+ was calculated to be Ka = 1.222 × 103. In addition, the AIEE fluorescent probe L could be applied to detection in real water samples with satisfactory recoveries in the range 99.10–102.90% in lake water and 98.49–102.37% in tap water.

scholarly journals Isatin as a simple, highly selective and sensitive colorimetric sensor for fluoride anion

2020 ◽  
Vol 26 (1) ◽  
pp. 14-19 ◽  
Author(s):  
Azeem Haider ◽  
Mukhtiar Ahmed ◽  
Muhammad Faisal ◽  
Muhammad Moazzam Naseer
Keyword(s):  
Color Change ◽  
Colour Change ◽  
High Sensitivity ◽  
Fluoride Anion ◽  
Base Interaction ◽  
Spectral Changes ◽  
Vis Spectroscopy ◽  
Sensitivity And Selectivity ◽  
Sensitive Sensor ◽  
Acid Base Interaction

AbstractHerein, we report the fluoride anion sensing properties of a commercially available and inexpensive organic compound, isatin, which is found to be a highly selective and sensitive sensor. In naked-eye experiments, by addition of fluoride anions, isatin shows a dramatic color change from pale yellow to violet at room temperature, while the addition of other anions, i.e. $\mathrm{Cl}^-,$$\mathrm{Br}^-,\mathrm I^-,\mathrm{ClO}_4^-,{\mathrm H}_2\mathrm{PO}_4^-\,\mathrm{and}\,\mathrm{PF}_6^-,$did not induce any colour change. Additionally, recognition and titration studies have also been done through UV/Vis spectroscopy. Isatin displayed a new absorption band at 533 nm after the addition of fluoride anions, which is presumably due to acid-base interaction between isatin and fluoride anions, while other anions did not trigger noticeable spectral changes. The detection limit was observed to be 0.367 ppm. DFT calculations were also performed to further explain the behavior of receptor 1 towards the Fˉ anion. Owing to high sensitivity and selectivity, isatin can be useful in the detection of biologically or environmentally important fluoride anions at very low concentration.

scholarly journals Colorimetric Sensing of Benzoyl Peroxide Based on the Emission Wavelength-Shift of CsPbBr3 Perovskite Nanocrystals

Chemosensors ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 319
Author(s):  
Li Zhang ◽  
Yimeng Zhu ◽  
Feiming Li ◽  
Linchun Zhang ◽  
Longjie You ◽  
...  
Keyword(s):  
Benzoyl Peroxide ◽  
Color Change ◽  
Fluorescence Emission ◽  
High Sensitivity ◽  
Emission Wavelength ◽  
Wavelength Shift ◽  
Colorimetric Sensing ◽  
Perovskite Nanocrystals ◽  
Sensitivity And Selectivity ◽  
Fluorescence Wavelength

Using the ionic salt characteristics of CsPbBr3 perovskite nanocrystals (CsPbBr3 NCs), the fluorescence wavelength of CsPbBr3−xIx NCs could be changed by the halogen exchange reaction between CsPbBr3 NCs and oleylammonium iodide (OLAM-I). Under the excitation of a 365 nm UV lamp and the increase of OLAM-I concentration, the content of iodine in CsPbBr3−xIx NCs increased, and the fluorescence emission wavelength showed a redshift from 511.6 nm to 593.4 nm, resulting in the fluorescence color change of CsPbBr3 NCs from green to orange-red. Since OLAM-I is a mild reducing agent and easily oxidized by benzoyl peroxide (BPO), a novel colorimetric sensing approach for BPO based on the fluorescence wavelength shift was established in this study. The linear relationship between the different wavelength shifts (Δλ) and the concentration of BPO (CBPO) is found to be in the range of 0 to 120 μmol L−1. The coefficient of alteration (R2) and the detection limit are 0.9933 and 0.13 μmol L−1 BPO, respectively. With this approach, the determination procedure of BPO in flour and noodle samples can be achieved in only a few minutes and exhibit high sensitivity and selectivity.

Synthesis of β- and β,β-substituted Morita–Baylis–Hillman adducts using a two-step protocol

2012 ◽  
Vol 90 (5) ◽  
pp. 450-463 ◽  
Author(s):  
David I. Magee ◽  
Same Ratshonka ◽  
Jessica McConaghy ◽  
Maggie Hood
Keyword(s):  
Knoevenagel Condensation ◽  
Condensation Reaction ◽  
Facile Synthesis ◽  
Aliphatic Aldehydes ◽  
Tert Butyl ◽  
Keto Esters ◽  
Knoevenagel Condensation Reaction

The synthesis of a large number of β- and β,β-substituted keto esters was successful by the use of the Knoevenagel condensation reaction. The stereoselectivity of these reactions was improved by alteration of various substituent groups. Although there were few examples of complete Z selectivity, the use of tert-butyl acetoacetate with either aromatic or aliphatic aldehydes afforded Z selectivity. The selective reductions of these substituted keto esters was successfully achieved by using a combination of NaBH4 and CeCl3·7H2O or Yb(OTf)3, which allowed a facile synthesis of a large number of stereochemically pure substituted Morita–Baylis–Hillman adducts, including β,β-substituted adducts.

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