ion pair
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2022 ◽  
pp. 100031
Author(s):  
Szabolcs Fekete ◽  
Hua Yang ◽  
Kevin Wyndham ◽  
Matthew Lauber

2021 ◽  
Author(s):  
Reginaldo Gomes ◽  
Chris Birch ◽  
Morgan Cencer ◽  
Chenyang Li ◽  
Seoung-Bum Son ◽  
...  

Selective CO2 capture and electrochemical conversion is an important tool in the fight against climate change. Industrially, CO2 is captured using a variety of aprotic solvents due to their high CO2 solubility. However, most research efforts on electrochemical CO2 conversion use aqueous media and are plagued by competing hydrogen evolution reaction (HER) from water breakdown. Fortunately, aprotic solvents can circumvent HER; making it important to develop strategies that enable integrated CO2 capture and conversion in an aprotic solvent. However, the influence of ion solvation and solvent selection within nonaqueous electrolytes for efficient and selective CO2 reduction is unclear. In this work, we show that bulk solvation behavior within the nonaqueous electrolyte can control the CO2 reduction reaction and product distribution occurring at the catalyst-electrolyte interface. We study different TBA (tetrabutylammonium) salts in two electrolyte systems with glyme-ethers (e.g., 1,2 dimethoxyethane or DME) and dimethylsulfoxide (DMSO) as a low and high dielectric constant medium, respectively. Using spectroscopic tools, we quantify the fraction of ion pairs that form within the electrolyte and show how ion-pair formation is prevalent in DME electrolytes and is dependent on anion type. More importantly, we show as ion-pair formation decreases within the electrolyte, CO2 current densities increases, and a higher CO Faradaic efficiency is observed at low overpotentials. Meanwhile, in an electrolyte medium where ion-pair fraction does not change with anion type (such as in DMSO), a smaller influence of solvation was observed on CO2 current densities and product distribution. By directly coupling bulk solvation to interfacial reactions and product distribution, we showcase the importance and utility of controlling the reaction microenvironment in tuning electrocatalytic reaction pathways. Insights gained from this work will enable novel electrolyte design for efficient and selective CO2 conversion to desired fuels and chemicals


2021 ◽  
Vol 15 (1) ◽  
pp. 34
Author(s):  
Lili He ◽  
Di Xiong ◽  
Lan Ma ◽  
Yan Liang ◽  
Teng Zhang ◽  
...  

This research aimed to explore how Strychnine (Str) ion-pair compounds affect the in vitro transdermal process. In order to prevent the influence of different functional groups on skin permeation, seven homologous fatty acids were selected to form ion-pair compounds with Str. The in vitro permeation fluxes of the Str ion-pair compounds were 2.2 to 8.4 times that of Str, and Str-C10 had the highest permeation fluxes of 42.79 ± 19.86 µg/cm2/h. The hydrogen bond of the Str ion-pair compounds was also confirmed by Fourier Transform Infrared (FTIR) Spectroscopy, Nuclear Magnetic Resonance (NMR) Spectroscopy and molecular simulation. In the process of molecular simulation, the intercellular lipid and the viable skin were represented by ceramide, cholesterol and free fatty acid of equal molar ratios and water, respectively. It was found by the binding energy curve that the Str ion-pair compounds had better compatibility with the intercellular lipid and water than Str, which indicated that the affinity of Str ion-pair compounds and skin was better than that of Str and skin. Therefore, it was concluded that Str ion-pair compounds can be distributed from the vehicle to the intercellular lipid and viable skin more easily than Str. These findings broadened our knowledge about how Str ion-pair compounds affect the transdermal process.


2021 ◽  
Vol 22 (2) ◽  
pp. 367-375
Author(s):  
Theia'a Najim Al-Sabha ◽  
Mohamed Yahya Dhamra

A sensitive spectrofluorimetric method has been developed for the analysis of some medicines containing primary, secondary, and tertiary amino groups, namely Diclofenac (DIC), Domperidone (DOM), Famotidine (FAM), and Propranolol (PRO), in their pure and medicinal forms. The method is based on the quenching of the fluorescence intensity of rhodamine 6G (R6G) through the formation of ion-pair complexes between the above medicines and the R-6G reagent, which is measured at 552 nm after excitation at 402 nm. The calibration graphs were rectilinear in the concentration ranges of 0.10- 9.00, 0.05-15.00, 0.10-14.0 and 0.05-5.00 µg mL-1 for above medicines respectively. The recovery (%) values were ranged between 99.45%- 100.97%. The detection limits ranged in the concentration of 0.243-0.754 µg/mL, and the limits of quantitation were 0.806- 2.420 µgmL-1 for all drugs. The method was successfully applied for the determination of these drugs in their pharmaceutical preparations.


2021 ◽  
Author(s):  
Kori Sye ◽  
Clare Leahy ◽  
Josh Vura-Weis

Bridged μ-oxo iron bisporphyrins serve as photocatalysts for oxidative organic transformations, but suffer from low quantum efficiency. We use femtosecond optical and M2,3-edge XANES spectroscopy to investigate the early photodynamics of the μ-oxo iron bisporphyrin, (TPPFe)2O, providing evidence for the preferential formation of an TPPFe(III)+/TPPFe(III)-O- ion pair state instead of the desired TPPFe(II)/TPPFe(IV)=O.


2021 ◽  
Author(s):  
Xuemei Wang ◽  
Liang Zhou ◽  
Hongkui Zhang ◽  
Xiaoyu Ren ◽  
Guowei Gao ◽  
...  
Keyword(s):  
Ion Pair ◽  

Synthesis ◽  
2021 ◽  
Author(s):  
Kirill Nikitin ◽  
Anna C. Vetter ◽  
Helge Müller-Bunz ◽  
Jimmy Muldoon

AbstractWe have earlier shown how the Wittig chemistry can be done using novel Eigenbase phosphonium carboxylate reagents. Here we discuss the phenomenon of ion pairing, their solution tautomerism, solid-state structure, and mechanistic aspects of olefination. The results point to a complex process involving unfamiliar H-bond-driven ion-pair equilibria followed by standard Wittig reaction steps.


Author(s):  
Narender Malothu ◽  
Sowjanya Ravuri ◽  
Balakrishna Muthyala ◽  
Narayana Rao Alla ◽  
Anka Rao Areti

Aim: To develop a simple spectroscopic method for estimation of doxylamine (DOX) succinate in its tablet dosage form and human plasma with the aid of an ion-pair complex formation. Methods: In this method, methyl orange (0.05 % w/v) dye was used to form an ion-pair complex in acetate buffer (1M; pH: 5.00) at 300 C ± 20C. The ion-pair complex formed was extracted with chloroform. The maximum absorbance for the ion-pair complex was measured at 420 nm. Results and discussion: The method conditions were obeyed Beer's law in the concentrations ranging from 5-25 µg/mL of DOX succinate with a correlation coefficient (r2) of 0.992. The ion-pair (drug-dye) complex was formed in a 1:1 ratio which was demonstrated by Jobs' method of continuous variation. The method was satisfied the validation criteria as per ICH (Q2R1) guidelines. Accuracy studies showed 99.06-100.9 % recovery of the analyte. The responses of the precision and robustness were found within acceptable limits (<2% RSD). The LOD and LOQ values were found as 0.31 and 0.939 µg/mL, respectively. Conclusion: The developed method was simple, specific, and economical and requires a short analysis time. Therefore it could be considered for precise analysis of DOX succinate in biological matrices.


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