scholarly journals Ion Pair−π Interactions

2015 ◽  
Vol 137 (34) ◽  
pp. 11047-11056 ◽  
Author(s):  
Kaori Fujisawa ◽  
Marie Humbert-Droz ◽  
Romain Letrun ◽  
Eric Vauthey ◽  
Tomasz A. Wesolowski ◽  
...  
Keyword(s):  
Ion Pair ◽  
Π Interactions

Bis[1-(4-bromobenzyl)-3-methylpyrazinium] bis(1,2-dicyanoethene-1,2-dithiolato-κ3 S,S′)nickelate(II)

2006 ◽  
Vol 62 (4) ◽  
pp. m767-m769
Author(s):  
Chun-Lin Ni ◽  
Ming-Guo Liu
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Ion Pair ◽  
Coordination Geometry ◽  
Π Interactions ◽  
Compound C ◽  
Square Planar

The title compound, (C12H12BrN2)[Ni(C4N2S2)2], is an ion-pair complex, isostructural with the Cl-containing analogue. The anion lies on an inversion centre and the NiII ion is coordinated by four S atoms, giving the expected square-planar coordination geometry. The cation adopts a conformation where the benzene and pyrazine rings are twisted with respect to the plane of the central C—C—N chain which links them. C—H...S and π–π interactions between cations and anions are observed in the crystal structure, and C—H...π interactions mediate the formation of ribbons of cations.

Tritopic ion-pair receptors based on anion–π interactions for selective CaX2 binding

2018 ◽  
Vol 47 (24) ◽  
pp. 7883-7887 ◽  
Author(s):  
Jian Luo ◽  
Yu-Fei Ao ◽  
Christian Malm ◽  
Johannes Hunger ◽  
Qi-Qiang Wang ◽  
...  
Keyword(s):  
Binding Sites ◽  
Ion Pair ◽  
Π Interactions ◽  
Pentaethylene Glycol

Selective ion-pair binding of CaX2 (X = Br− and I−) was realized by a tritopic receptor incorporating two homoditopic anion–π binding sites and a pentaethylene glycol moiety.

Chloroquine-iron(III) tetra-arylporphyrin interactions and their effect on chloroquine oxidations catalyzed by iron(III) tetra-arylporphyrins

2005 ◽  
Vol 09 (05) ◽  
pp. 326-333 ◽  
Author(s):  
Ádamo César M. A. dos Santos ◽  
John R. Lindsay Smith ◽  
Marilda D. Assis
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Spectroscopic Study ◽  
Oxidation Product ◽  
Ion Pair ◽  
Oxidation Products ◽  
Methanolic Solution ◽  
Aqueous Buffer ◽  
Π Interactions ◽  
Π Complexation

This paper reports a UV-Vis spectroscopic study on the interactions of chloroquine with anionic, cationic and neutral tetra-arylporphyrins and their iron(III) complexes in aqueous buffer and in methanolic solution. This study reveals that in water at pH 6.4 cooperative ion-pair and π-π interactions lead to complex formation between the anionic porphyrin species and chloroquine. In methanolic solution no π-π complexation is observed. The neutral and cationic porphyrins and metalloporphyrins do not form complexes with chloroquine. On the basis of these results, the iron(III) porphyrins have been used as catalysts for the oxidation of chloroquine by iodosylbenzene. The main oxidation product in all systems is monodesethylchloroquine. The anionic iron(III) porphyrins are the most active catalysts; in aqueous solution they are selective for oxidative deethylation whereas in methanol they also give five other oxidation products. The cationic and neutral iron(III) porphyrins are poor or inactive catalysts for chloroquine oxidation by iodosylbenzene. The effect of iron(III) porphyrin/chloroquine interactions on the yields and selectivity of the oxidation is discussed.

scholarly journals Crystal structure and Hirshfeld surface analysis of 2-phenyl-1H-phenanthro[9,10-d]imidazol-3-ium benzoate

2020 ◽  
Vol 76 (5) ◽  
pp. 724-727
Author(s):  
Ruby Ahmed ◽  
Onur Erman Doğan ◽  
Farman Ali ◽  
Musheer Ahmad ◽  
Adeeba Ahmed ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzoic Acid ◽  
Surface Analysis ◽  
Ion Pair ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Acid Form ◽  
Π Interactions ◽  
Compound C

In the title compound, C21H15N2 +·C7H5O2 −, 2-phenyl-1H-phenanthro[9,10-d]imidazole and benzoic acid form an ion pair complex. The system is consolidated by hydrogen bonds along with π–π interactions and N—H...π interactions between the constituent units. For a better understanding of the crystal structure and intermolecular interactions, a Hirshfeld surface analysis was performed.

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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