Construction of a [2]pseudorotaxane and a [3]pseudorotaxane based on perbromoethylated pillar[5]arene/pyridinium iodide ion-pair recognition

2019 ◽  
Vol 55 (31) ◽  
pp. 4527-4530 ◽  
Author(s):  
Li Shao ◽  
Bin Hua ◽  
Jiyong Liu ◽  
Feihe Huang
Keyword(s):  
Ion Pair ◽  
Iodide Ion

Herein we report the preparation of a [2]pseudorotaxane and a [3]pseudorotaxane based on perbromoethylated pillar[5]arene/pyridinium iodide ion-pair recognition.

scholarly journals Ion-Pair Formation of [CoIII(pn)2(Cl)(L)2+····· I−] by Aqueous-Organic Solvent Medium Enhanced Photoreduction: A Perspective Regression Analysis

2020 ◽  
Vol 32 (6) ◽  
pp. 1379-1383
Author(s):  
L. Devaraj Stephen ◽  
S.G. Gunasekaran ◽  
M. Soundarrajan
Keyword(s):  
Charge Transfer ◽  
Organic Solvent ◽  
High Performance ◽  
Ion Pair ◽  
Pair Formation ◽  
The Novel ◽  
Solvent Medium ◽  
Ion Pair Formation ◽  
Iodide Ion

Reduction of CoIII centre in CoIII(pn)2(Cl)(L)2+ with reference to solvent medium and structure of the complex via ion pair charge transfer (IPCT) paves way for the novel reaction mechanism route. In this work, we prepared, characterized and photoinduced the complexes CoIII(pn)2(Cl)(L)2+ (where L = RC6H4NH2, R = m-OMe, p-F and H) in the presence of iodide ion. Quantum yield for 254 nm excitation of CoIII(pn)2(Cl)(L)2+(where L = RC6H4NH2, R = m-OMe, p-F and H) in water-1,4-dioxane mixtures (Diox = 0, 5, 10, 15, 20, 25, and 30% (v/v)) were also derived for all the complexes in presence of added iodide ion, in which CoIII was reduced via [CoIII(pn)2(Cl)(L)2+….. I-] ion-pair formation. The photoinduced state is ion-pair charge transfer transition state and the quantum efficiency is solvent reliant and they are non-reactive. That is, change in ΦCo(II) is dependable with observed increase in xDiox of the mixed solvent medium. Correlation analysis using empirical parameters εr, Y, ET N and DNN provides a model to understand the solvent medium participation and interaction. This work gains an insight into the role of aqueous-organic solvent medium in CoIII(pn)2(Cl)(L)2+ photoreduction, which may be of great significance in developing novel approaches in the field of high performance catalysis

Some physical properties of aqueous solutions of tetramethylammonium bromide and tetramethylammonium iodide

1965 ◽  
Vol 18 (8) ◽  
pp. 1161 ◽  
Author(s):  
BJ Levien
Keyword(s):  
Aqueous Solutions ◽  
Physical Properties ◽  
Activity Coefficients ◽  
Ion Association ◽  
Ion Pair ◽  
Standard Entropy ◽  
Solubility In Water ◽  
Iodide Ion ◽  
Tetramethylammonium Bromide

The activity coefficients up to saturation, some conductances and densities, and the solubility in water have been measured for tetramethylammonium bromide and tetramethylammonium iodide. Ion association exists and the ion-pair constants have been calculated by three methods. The standard entropy of the aqueous (CH3)4N+ ion has been calculated.

National primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2019

2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk
Keyword(s):  
Gamma Radiation ◽  
Energy Flux ◽  
Primary Standard ◽  
Average Energy ◽  
Ion Pair ◽  
X Rays ◽  
Exposure Rate ◽  
Ionization Chambers ◽  
Air Kerma ◽  
Air Kerma Rate

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.

Extractive Spectrophotometric Method for the Determination of Glibenclamide by Ion-Pair Complex in Pure Form and Pharmaceutical Formulation

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
RUAA MUAYAD MAHMOOD ◽  
HAMSA MUNAM YASSEN ◽  
SAMAR , NAJWA ISSAC ABDULLA AHMED DARWEESH ◽  
NAJWA ISSAC ABDULLA
Keyword(s):  
Spectrophotometric Method ◽  
Molar Absorptivity ◽  
Ion Pair ◽  
Pharmaceutical Formulation ◽  
Ratio Method ◽  
Colored Complex ◽  
Colored Product ◽  
Method Of Continuous Variation ◽  
Job's Method

Simple, rapid and sensitive extractive spectrophotometric method is presented for the determination of glibenclamide (Glb) based on the formation of ion-pair complex between the Glb and anionic dye, methyl orange (MO) at pH 4. The yellow colored complex formed was quantitatively extracted into dichloromethane and measured at 426 nm. The colored product obeyed Beer’s law in the concentration range of (0.5-40) μg.ml-1. The value of molar absorptivity obtained from Beer’s data was found to be 31122 L.mol-1.cm-1, Sandell’s sensitivity value was calculated to be 0.0159 μg.cm-2, while the limits of detection (LOD) and quantification (LOQ) were found to be 0.1086 and 0.3292 μg.ml-1, respectively. The stoichiometry of the complex created between the Glb and MO was 1:1 as determined via Job’s method of continuous variation and mole ratio method. The method was successfully applied for the analysis of pharmaceutical formulation.

Stereospecific 1,3-H Transfer of Indenols Proceeds via Persistent Ion-Pairs Anchored By NH···Pi Interactions

2018 ◽  
Author(s):  
David Ascough ◽  
Fernanda Duarte ◽  
Robert Paton
Keyword(s):  
Computational Analysis ◽  
Ion Pairs ◽  
Ion Pair ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Chirality Transfer ◽  
Activation Barriers ◽  
Sense And Avoid ◽  
Phase Dynamics ◽  
Pi Interactions

The base-catalyzed rearrangement of arylindenols is a rare example of a suprafacial [1,3]-hydrogen atom transfer. The mechanism has been proposed to proceed via sequential [1,5]-sigmatropic shifts, which occur in a selective sense and avoid an achiral intermediate. A computational analysis using quantum chemistry casts serious doubt on these suggestions: these pathways have enormous activation barriers and in constrast to what is observed experimentally, they overwhelmingly favor a racemic product. Instead we propose that a suprafacial [1,3]-prototopic shift occurs in a two-step deprotonation/reprotonation sequence. This mechanism is favored by 15 kcal mol<sup>-1</sup> over that previously proposed. Most importantly, this is also consistent with stereospecificity since reprotonation occurs rapidly on the same p-face. We have used explicitly-solvated molecular dynamics studies to study the persistence and condensed-phase dynamics of the intermediate ion-pair formed in this reaction. Chirality transfer is the result of a particularly resilient contact ion-pair, held together by electrostatic attraction and a critical NH···p interaction which ensures that this species has an appreciable lifetime even in polar solvents such as DMSO and MeOH.

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