scholarly journals A multi-functional chemosensor for highly selective ratiometric fluorescent detection of silver(I) ion and dual turn-on fluorescent and colorimetric detection of sulfide

2018 ◽  
Vol 5 (6) ◽  
pp. 180293 ◽  
Author(s):  
Ji Hye Kang ◽  
Ju Byeong Chae ◽  
Cheal Kim
Keyword(s):  
Theoretical Calculations ◽  
Colorimetric Detection ◽  
Fluorescence Emission ◽  
Binding Mode ◽  
Fluorescent Detection ◽  
Mass Spectral ◽  
H Nmr ◽  
Wide Ph Range ◽  
Ph Range ◽  
Nmr Titrations

A multi-functional chemosensor 1 as silver and sulfide detector was synthesized by the combination of octopamine and 4-dimethylaminocinnamaldehyde. Sensor 1 exhibited a ratiometric fluorescence emission for Ag + from blue to sky. The binding mode of 1 and Ag + turned out to be a 1 : 1 ratio as determined using Job plot and electrospray ionization (ESI) mass spectral analyses. The sensing mechanism of 1 with silver ion was unravelled by 1 H NMR titrations and theoretical calculations. Sensor 1 also discerned sulfide by enhancing fluorescence intensity and changing colour from yellow to colourless in aqueous solution. The sensing properties of 1 toward S 2− were investigated by using ESI-mass analysis, Job plot and 1 H NMR titrations. Moreover, 1 could be used as a detector for sulfide in a wide pH range.

scholarly journals Tuning the Properties of High Molecular Weight Chitosans to Develop Full Water Solubility Within a Wide pH Range

2020 ◽  
Author(s):  
Anderson Fiamingo ◽  
Sergio Paulo Campana Filho ◽  
Osvaldo Novais Oliveira Junior
Keyword(s):  
Molecular Weight ◽  
Biomedical Applications ◽  
Random Distribution ◽  
Water Solubility ◽  
Aqueous Media ◽  
Degree Of Polymerization ◽  
Molecular Weights ◽  
H Nmr ◽  
Wide Ph Range ◽  
Ph Range

<p>The preparation of chitosans soluble in physiological conditions has been sought for years, but so far solubility in non-acidic aqueous media has only been achieved at the expense of lowering chitosan molecular weight. In this work, we applied the multistep ultrasound-assisted deacetylation process (USAD process) to β-chitin and obtained extensively deacetylated chitosans with high molecular weights (Mw ≥ 1,000,000 g mol<sup>-1</sup>). The homogeneous <i>N</i>-acetylation of a chitosan sample resulting from three consecutive USAD procedures allowed us to produce chitosans with a high weight average degree of polymerization (DPw ≈ 6,000) and tunable degrees of acetylation (DA from 5 to 80%). <i>N</i>-acetylation was carried out under mild conditions to minimize depolymerization, while preserving a predominantly random distribution of 2-amino-2-deoxy-D-glucopyanose (<i>GlcN</i>) and 2-acetamido-2-deoxy-D-glucopyanose (<i>GlcNAc</i>) units. This close to random distribution, inferred with deconvolution of nuclear magnetic resonance (<sup>1</sup>H NMR) spectra, is considered as responsible for the solubility within a wide pH range. Two of the highly <i>N</i>-acetylated chitosans (DA ≈ 60 % and ≈ 70 %) exhibited full water solubility even at neutral pH, which can expand the biomedical applications of chitosans. </p>

Preparation and Structural Characterization of Methylmercury(II) Complexes of 5-Aza- and 6-Azauracil Derivatives

1987 ◽  
Vol 42 (12) ◽  
pp. 1556-1562 ◽  
Author(s):  
W. S. Sheldrick ◽  
S. Heeb
Keyword(s):  
Structural Analysis ◽  
Binding Sites ◽  
Ionic Complex ◽  
X Ray ◽  
H Nmr ◽  
Ph Values ◽  
Nmr Data ◽  
Wide Ph Range ◽  
Ph Range

Abstract1:1 Methylmercury(II) complexes of the anti-tumour agent 6-azauracil (6AUH2) and its deriva­tives 6-azathymine (6ATH2). 1-methyl-6-azauracil (6AMUH) and 1-methyl-6-azathymine (6AMTH) have been isolated from aqueous solutions of CH3HgOH and the respective base. N3-Coordination was established by X-ray structural analysis for both [(CH3Hg)6 AUH] (1) (pH 6-8) and [(CH3Hg)6 AMT] (5) (pH 4-12); in addition 1H NMR data are in accordance with an identical binding site in the complexes [(CH3Hg)6AMU] (3) and [(CH3Hg)6 ATH] (4). Using an excess of CH3HgOH. 2:1 complexes with N1, N3-coordination may be prepared for both 6 AUH: and 5 AUH2 in a wide pH range (4-12 and 6-12 respectively). At pH values of 3-4 a 3:1 complex [(CH3Hg)35 AU]NO3 (7), with N1, N3, N5-coordination may be isolated: the binding sites were confirmed by X-ray structural analysis. In no case could an ionic complex with N6- coordination be isolated for a 6-azapyrimidine derivative. The binding preferences of the bases are discussed in the light of MNDO calculations.

scholarly journals Rational Design of an ICT-Based Chemodosimeter with Aggregation-Induced Emission for Colorimetric and Ratiometric Fluorescent Detection of Cyanide in a Wide pH Range

ACS Omega ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 5287-5296
Author(s):  
Sachin D. Padghan ◽  
Li-Ching Wang ◽  
Wei-Chi Lin ◽  
Jiun-Wei Hu ◽  
Wen-Ching Liu ◽  
...  
Keyword(s):  
Rational Design ◽  
Fluorescent Detection ◽  
Aggregation Induced Emission ◽  
Wide Ph Range ◽  
Ph Range

scholarly journals Tuning the Properties of High Molecular Weight Chitosans to Develop Full Water Solubility Within a Wide pH Range

2020 ◽  
Author(s):  
Anderson Fiamingo ◽  
Sergio Paulo Campana Filho ◽  
Osvaldo Novais Oliveira Junior
Keyword(s):  
Molecular Weight ◽  
Biomedical Applications ◽  
Random Distribution ◽  
Water Solubility ◽  
Aqueous Media ◽  
Degree Of Polymerization ◽  
Molecular Weights ◽  
H Nmr ◽  
Wide Ph Range ◽  
Ph Range

<p>The preparation of chitosans soluble in physiological conditions has been sought for years, but so far solubility in non-acidic aqueous media has only been achieved at the expense of lowering chitosan molecular weight. In this work, we applied the multistep ultrasound-assisted deacetylation process (USAD process) to β-chitin and obtained extensively deacetylated chitosans with high molecular weights (Mw ≥ 1,000,000 g mol<sup>-1</sup>). The homogeneous <i>N</i>-acetylation of a chitosan sample resulting from three consecutive USAD procedures allowed us to produce chitosans with a high weight average degree of polymerization (DPw ≈ 6,000) and tunable degrees of acetylation (DA from 5 to 80%). <i>N</i>-acetylation was carried out under mild conditions to minimize depolymerization, while preserving a predominantly random distribution of 2-amino-2-deoxy-D-glucopyanose (<i>GlcN</i>) and 2-acetamido-2-deoxy-D-glucopyanose (<i>GlcNAc</i>) units. This close to random distribution, inferred with deconvolution of nuclear magnetic resonance (<sup>1</sup>H NMR) spectra, is considered as responsible for the solubility within a wide pH range. Two of the highly <i>N</i>-acetylated chitosans (DA ≈ 60 % and ≈ 70 %) exhibited full water solubility even at neutral pH, which can expand the biomedical applications of chitosans. </p>

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

High degradation efficiency of sulfamethazine with the dual-reaction-center Fe-Mn-SiO2 Fenton-like nanocatalyst in a wide pH range

2021 ◽  
Author(s):  
Manoj Kumar Panjwani ◽  
Qing Wang ◽  
Yueming Ma ◽  
Yuxuan Lin ◽  
Feng Xiao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Reaction Center ◽  
Degradation Efficiency ◽  
Heterogeneous Fenton ◽  
Wide Ph Range ◽  
Ph Range

The development of a heterogeneous Fenton-like catalyst, possessing high degradation efficiency in a wide pH range, is crucial for wastewater treatment. The Fe-Mn-SiO2 catalyst was designed, and prepared by a...

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