scholarly journals A Subtle Change in Substituent Enabled Multi-Ways Fluoride Signals Including Paper-Strip Colorimetric Detection Using Urea Receptor Functionalized 1,1,4,4-Tetracyanobuta-1,3-Diene-Based Push-Pull Chromophore

2020 ◽  
Author(s):  
Vijayendran Gowri ◽  
Sachin Jalwal ◽  
Arif Hassan Dar ◽  
Arya Gopal ◽  
Azhagumuthu Muthukrishnan ◽  
...  
Keyword(s):  
Color Change ◽  
Intramolecular Charge Transfer ◽  
Colorimetric Detection ◽  
Paper Strip ◽  
Efficient System ◽  
Subtle Change ◽  
Biologically Relevant ◽  
Tissue Paper ◽  
Naked Eye ◽  
Homo Lumo

A simple color change detection by the naked-eye using untreated paper for a biologically relevant fluoride (F<sup>–</sup>) anion in water is a challenge. New non-planar push-pull chromophore involving intramolecular charge-transfer (ICT) from urea donor in 2,3-disubstituted-1,1,4,4-tetracyanobuta-1,3-diene (TCBD) turns out to be an efficient system for detecting F<sup>– </sup>ion giving various output signals. But, replacing phenyl (Ph) at <i>C</i><sub>3</sub>-position with 4-(dimethylamino)phenyl (DMA) led to the absence of colorimetric and fluorometric detections due to the masking and quenching, nature of strong ICT by the DMA. NMR and electrochemical studies revealed that the sensing mechanism is governed by H-bonding as well as the deprotonation of N–H attached with TCBD moiety which reduces the HOMO–LUMO gap and causes the dramatic color change. Coupled with excellent sensitivity (3 ppm) and specificity towards F<sup>–</sup>, a successful demonstration of cheap tissue paper-based visual strip-detection in aqueous is presented.

scholarly journals A Subtle Change in Substituent Enabled Multi-Ways Fluoride Signals Including Paper-Strip Colorimetric Detection Using Urea Receptor Functionalized 1,1,4,4-Tetracyanobuta-1,3-Diene-Based Push-Pull Chromophore

2020 ◽  
Author(s):  
Vijayendran Gowri ◽  
Sachin Jalwal ◽  
Arif Hassan Dar ◽  
Arya Gopal ◽  
Azhagumuthu Muthukrishnan ◽  
...  
Keyword(s):  
Color Change ◽  
Intramolecular Charge Transfer ◽  
Colorimetric Detection ◽  
Paper Strip ◽  
Efficient System ◽  
Subtle Change ◽  
Biologically Relevant ◽  
Tissue Paper ◽  
Naked Eye ◽  
Homo Lumo

A simple color change detection by the naked-eye using untreated paper for a biologically relevant fluoride (F<sup>–</sup>) anion in water is a challenge. New non-planar push-pull chromophore involving intramolecular charge-transfer (ICT) from urea donor in 2,3-disubstituted-1,1,4,4-tetracyanobuta-1,3-diene (TCBD) turns out to be an efficient system for detecting F<sup>– </sup>ion giving various output signals. But, replacing phenyl (Ph) at <i>C</i><sub>3</sub>-position with 4-(dimethylamino)phenyl (DMA) led to the absence of colorimetric and fluorometric detections due to the masking and quenching, nature of strong ICT by the DMA. NMR and electrochemical studies revealed that the sensing mechanism is governed by H-bonding as well as the deprotonation of N–H attached with TCBD moiety which reduces the HOMO–LUMO gap and causes the dramatic color change. Coupled with excellent sensitivity (3 ppm) and specificity towards F<sup>–</sup>, a successful demonstration of cheap tissue paper-based visual strip-detection in aqueous is presented.

scholarly journals Detection of organic amines using a ratiometric chromophoric fluorescent probe with a significant emission shift

2020 ◽  
Vol 44 (7-8) ◽  
pp. 475-481
Author(s):  
Dan Wu ◽  
Yi Liu ◽  
Fei Zheng ◽  
Shi-Qi Rong ◽  
Tao Yang ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Nucleophilic Addition ◽  
High Selectivity ◽  
Color Change ◽  
Intramolecular Charge Transfer ◽  
Signaling Mechanism ◽  
Eye Color ◽  
Naked Eye ◽  
Spectrometric Measurements ◽  
Organic Amines

Taking advantages of both the well-known α,β-unsaturated structure and the special nucleophilicity of organic amines toward its acceptor moieties, intramolecular charge transfer as a signaling mechanism is used to design and synthesize a new ratiometric chromophoric fluorescent probe (BI-CA-ID) with large emission shifts toward organic amines. This probe is employed for the detection of organic amines with high selectivity and sensitivity and a “naked-eye” color change (from red to colorless). Ultraviolet–visible and fluorescence spectrometric measurements are used to determine detection limits as low as 0.024 and 0.43 μM. Furthermore, nucleophilic addition of the amine on the α,β-unsaturated of BI-CA-ID indicated that the sensing mechanism occurs via interruption of the π-conjugation.

Colorimetric Detection of Melamine Based on Poly-Thymine Stabilized Gold Nanoparticles

2013 ◽  
Vol 790 ◽  
pp. 619-622
Author(s):  
Chong Jin ◽  
Hui Min Zhao ◽  
Meng Liu ◽  
Jun Ping Tian ◽  
Xie Quan
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
Limit Of Detection ◽  
Pure Water ◽  
Colorimetric Detection ◽  
Colorimetric Method ◽  
Milk Powder ◽  
Aggregation Process ◽  
Naked Eye ◽  
Fresh Milk

A simple, fast and reliable colorimetric method for melamine detection based on gold nanoparticles (AuNPs) and poly-thymine (poly-T) is reported. Poly-T strands attract AuNPs through static electricity and keep them stable against aggregation in the presence of NaCl. The affinity between melamine and poly-T, hydrogen bond, frees AuNP from the protection provided by poly-T and thus makes AuNPs aggregate in the presence of NaCl. The color change of AuNPs from wine red to blue can be observed immediately by the naked eye during the aggregation process, and can be accurately recorded with the help of a UV/vis spetrophotometer within 5 minutes. The limit of detection (LOD) of melamine in pure water is 0.146 μmol/L with a linear range from 0.2×10-7 mol/L to 10.0×10-7 mol/L. In fresh milk and milk powder, the LOD is respectively as low as 2.37 μmol/L and 5.36 μmol/L.

Quantum chemical insight into the molecular structure of L-chemosensor 1,3-dimethyl-5-(thien-2-ylmethylene)-pyrimidine-2,4,6-(1H,3H,5H)-trione: Naked-eye colorimetric detection of copper(II) anions

2018 ◽  
Vol 17 (01) ◽  
pp. 1850005 ◽  
Author(s):  
Assem Barakat ◽  
Mohammad Shahidul Islam ◽  
Abdullah Mohammed Al-Majid ◽  
Hazem A. Ghabbour ◽  
Saleh Atef ◽  
...  
Keyword(s):  
Color Change ◽  
Colorimetric Detection ◽  
Intermolecular Forces ◽  
Mulliken Charge ◽  
X Ray Diffraction ◽  
Gaseous State ◽  
H Nmr ◽  
Reactivity Descriptor ◽  
Homo Lumo ◽  
Anion Type

A sensitive colorimetric L-chemosensor 1,3-dimethyl-5-(thien-2-ylmethylene)-pyrimidine-2,4,6-(1[Formula: see text]-trione was developed by Knoevenagel combination of barbituric acid with thiophene aldehyde chelating moiety. The sensor displayed a high colorimetric Cu(II)X2 response; a dramatic methanol color change was recorded depending on anion type ([Formula: see text], Cl[Formula: see text], ClO[Formula: see text], NO[Formula: see text], OAc[Formula: see text], and SO[Formula: see text]. Off-on-off decolorized halochromism of the L-chemosensor/CuBr2 was recorded in an acidic medium. The structure of the L-chemosensor was confirmed by single-crystal X-ray diffraction, elemental analysis, and molecular spectroscopic tools such as UV–Vis, Fourier transform infra-red, 1H, and [Formula: see text]C nuclear magnetic resonance (NMR) spectroscopy. The thermal stability of the L-chemosensor was experimentally evaluated by thermogravimetric analysis. The structural optimized parameters of the ligand matched the crystallographic data, and the intermolecular forces were computed by Hirshfeld surface analysis. Electronic absorption in several solvents and 1H NMR were correlated with the computed spectra in the gaseous state. The HOMO/LUMO, global reactivity descriptor quantum parameters, Mulliken charge population, and molecular electrostatic potential of the L-chemosensor were also computed.

Fluoride anion sensing using colorimetric reagents containing binaphthyl moiety and urea binding site

2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Roman Mikláš ◽  
Peter Kasák ◽  
Ferdinand Devínsky ◽  
Martin Putala
Keyword(s):  
Color Change ◽  
Colorimetric Detection ◽  
Fluoride Anion ◽  
Urea Derivatives ◽  
Anion Sensing ◽  
Naked Eye ◽  
Spectral Changes ◽  
Light Yellow ◽  
Nmr Data ◽  
Sensor Molecules

AbstractFour 1,1′-binaphthalene based bis-urea derivatives bearing aryl groups at end-on nitrogen atoms IIIa–d were synthesized as potential sensor molecules. These receptors show characteristic UV-VIS spectral changes on complexation with anions and they exhibit selective recognition of F− over other halide anions. Interaction of a fluoride anion with urea NH groups was confirmed by 1H NMR data. The presence of an electron-withdrawing nitro group in N′-aryls (receptors IIIa and IIIb) appeared to be necessary for naked-eye colorimetric detection. These receptors show dramatic color change from light-yellow to orange (IIIa) or to orange-red (IIIb) in the presence of guest fluoride anions already at concentrations of 10−5 mol dm−3 of the receptor and host.

scholarly journals A Naked-Eye Fluoride Ion Recognition Based Vanilin Derivative Chemosensors

2019 ◽  
Vol 2 (2) ◽  
pp. 110
Author(s):  
R Rahmawati ◽  
Bambang Purwono ◽  
Sabirin Matsjeh
Keyword(s):  
Hydrogen Bond ◽  
Color Change ◽  
Colorimetric Detection ◽  
Bond Formation ◽  
Fluoride Ion ◽  
Bonding Mechanism ◽  
Fluoride Ions ◽  
Hydrogen Bond Formation ◽  
Naked Eye ◽  
Basic Anion

Two new receptors S2 and S6 were designed and synthesized based on benzimidazole and azo-benzimidazole synthesized from vanillin for the colorimetric detection of fluoride ion. The presence of nitro group in S2 and azo in S6 makes –OH  proton (binding site) acidic and therefore it could deprotonate with addition of basic anion such as fluoride. Hydroxyl (–OH) functionality which detects basic fluoride ions via hydrogen-bonding mechanism wich is mechanism involved in the color change of receptor R2 and R6, its mean that initial hydrogen bond formation of F− ion with –OH group.

scholarly journals pH Dependence on Colorimetric Detection of Hg2+ by Histidine-Functionalized Gold Nanoparticles

2020 ◽  
Vol 20 (4) ◽  
pp. 941
Author(s):  
Dewi Eviane ◽  
Dwi Siswanta ◽  
Sri Juari Santosa
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
Ph Dependence ◽  
Colorimetric Detection ◽  
Trisodium Citrate ◽  
Industrial Facility ◽  
Naked Eye ◽  
Functionalized Gold Nanoparticles ◽  
Relative Standard ◽  
Optimum Ph

In this study, we successfully developed gold nanoparticles capped with histidine (His-AuNPs) for Hg2+ detection using trisodium citrate as the reducing agent. The optimum pH for the detection of Hg2+ by His-AuNPs was 12. The addition of Hg2+ to the His-AuNPs caused the color change from red to black-blue, which is readily detectable by the naked eye. This color change is followed by a decrease in the intensity of the primary Surface Plasmon Resonance (SPR) peak at a wavelength (λ) of 525 nm and an increase in the secondary peak at λ = 650 nm. His-AuNPs effectively detected Hg2+ with limits of detection and quantitation of 1.77 µM and 5.89 µM, respectively. His-AuNPs exhibited good performance for the detection of Hg2+ in waste water collected from a steel industrial facility in Banten Province, with a recovery and a percent relative standard deviation of 115% and 1.02%, respectively.

The Difference in Sensing Properties Towards Anions between Two Pyridinium Amide-Based Receptors with a Subtle Change of H-Bond Position

2020 ◽  
Vol 17 (6) ◽  
pp. 472-478
Author(s):  
Wei-tao Gong ◽  
Wei-dong Qu ◽  
Guiling Ning
Keyword(s):  
Fluorescence Enhancement ◽  
Small Difference ◽  
Fluorescence Emission ◽  
Subtle Change ◽  
Sensing Properties ◽  
Naked Eye ◽  
Recognition Ability ◽  
The Difference ◽  
L1 And L2

Two pyridinium amide-based receptors L1 and L2 with a small difference of H-bond position of the amide have been synthesized and characterized. Interestingly, they exhibited a huge difference in sensing towards AcO- and H2PO4 -, respectively. Receptor L1 was found to be ‘naked-eye’ selective for AcO- anions, while receptor L2 showed clear fluorescence enhancement selective to H2PO4 - anion. The recognition ability has been established by fluorescence emission, UV-vis spectra, and 1HNMR titration.

Naked-eye colorimetric detection of HCV RNA mediated by a 5′ UTR-targeted antisense oligonucleotide and plasmonic gold nanoparticles

The Analyst ◽  
2021 ◽  
Author(s):  
Almas Shamaila Mohammed ◽  
Aniket Balapure ◽  
Mahammad Nanne Khaja ◽  
Ramakrishnan Ganesan ◽  
Jayati Ray Dutta
Keyword(s):  
Gold Nanoparticles ◽  
Antisense Oligonucleotide ◽  
Early Stage ◽  
Colorimetric Detection ◽  
Sensitive Detection ◽  
Clinical Samples ◽  
Hcv Rna ◽  
Naked Eye

An Au NP based facile strategy for the rapid, early-stage, and sensitive detection of HCV RNA in clinical samples which avoids thiol tagging to the antisense oligonucleotide and expensive infrastructure is presented.

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