Monophotonic ionization through a long-lived ion pair: N,N,N',N'-tetramethyl-p-phenylenediamine in acetonitrile solution

1983 ◽  
Vol 87 (10) ◽  
pp. 1680-1682 ◽  
Author(s):  
Yoshinori Hirata ◽  
Noboru Mataga
2016 ◽  
Vol 45 (29) ◽  
pp. 11639-11643 ◽  
Author(s):  
K. Ziach ◽  
M. Karbarz ◽  
J. Romański

The modular design of ion pair receptors facilitated the preparation of a functionally analogous polymeric material able to extract sodium nitrite from acetonitrile solution.


1983 ◽  
Vol 97 (6) ◽  
pp. 569-572 ◽  
Author(s):  
Yoshinori Hirata ◽  
Masataka Takimoto ◽  
Noboru Mataga

1971 ◽  
Vol 49 (16) ◽  
pp. 2751-2754 ◽  
Author(s):  
D. R. Eaton ◽  
Linda Seville ◽  
J. P. Jesson

The structure of the ion pair formed between Co(II) bistripyrazolylmethane ions and PF6− ions in acetonitrile solution has been investigated. Isotropic shifts observed in the 19F nuclear magnetic resonance (n.m.r.) spectra of the anion have been used for this purpose. It is concluded that the preferred position of the anion lies close to the symmetry axis of the cobalt complex and that a contact ion pair is involved. This result is contrasted with previous studies of second sphere coordination involving neutral molecules.


2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk

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.


Author(s):  
RUAA MUAYAD MAHMOOD ◽  
HAMSA MUNAM YASSEN ◽  
SAMAR , NAJWA ISSAC ABDULLA AHMED DARWEESH ◽  
NAJWA ISSAC ABDULLA

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.


2018 ◽  
Author(s):  
David Ascough ◽  
Fernanda Duarte ◽  
Robert Paton

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.


Sign in / Sign up

Export Citation Format

Share Document