Electrochemical studies of the conformational and sodium cation complexation properties of calix[4]arenediquinones

1994 ◽  
Vol 90 (19) ◽  
pp. 2931 ◽  
Author(s):  
Zheng Chen ◽  
Philip A. Gale ◽  
Jennifer A. Heath ◽  
Paul D. Beer
Keyword(s):  
Sodium Cation ◽  
Electrochemical Studies ◽  
Cation Complexation

ChemInform Abstract: DYNAMICS OF SODIUM CATION COMPLEXATION BY CARBON- AND NITROGEN-PIVOT LARIAT ETHERS

1983 ◽  
Vol 14 (1) ◽  
Author(s):  
A. KAIFER ◽  
H. D. DURST ◽  
L. ECHEGOYEN ◽  
D. M. DISHONG ◽  
R. A. SCHULTZ ◽  
...  
Keyword(s):  
Sodium Cation ◽  
Lariat Ethers ◽  
Cation Complexation ◽  
Carbon And Nitrogen

Sodium cation complexation behavior of the heteroaromatic sidechains of histidine and tryptophan

2002 ◽  
pp. 1810-1811 ◽  
Author(s):  
Jiaxin Hu ◽  
Leonard J. Barbour ◽  
Riccardo Ferdani ◽  
George W. Gokel
Keyword(s):  
Sodium Cation ◽  
Cation Complexation

Dynamics of sodium cation complexation by carbon- and nitrogen-pivot lariat ethers

1982 ◽  
Vol 47 (16) ◽  
pp. 3195-3197 ◽  
Author(s):  
Angel Kaifer ◽  
H. Dupont Durst ◽  
Luis Echegoyen ◽  
Dennis M. Dishong ◽  
Rose Ann Schultz ◽  
...  
Keyword(s):  
Sodium Cation ◽  
Lariat Ethers ◽  
Cation Complexation ◽  
Carbon And Nitrogen

scholarly journals The Role of Triazole and Glucose Moieties in Alkali Metal Cation Complexation by Lower-Rim Tertiary-Amide Calix[4]arene Derivatives

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 470
Author(s):  
Josip Požar ◽  
Marija Cvetnić ◽  
Andrea Usenik ◽  
Nikola Cindro ◽  
Gordan Horvat ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Sodium Cation ◽  
Cation Binding ◽  
Medium Effect ◽  
Cation Complexation ◽  
Tertiary Amide ◽  
Dissolution Enthalpies ◽  
Metal Cation Complexation

The binding of alkali metal cations with two tertiary-amide lower-rim calix[4]arenes was studied in methanol, N,N-dimethylformamide, and acetonitrile in order to explore the role of triazole and glucose functionalities in the coordination reactions. The standard thermodynamic complexation parameters were determined microcalorimetrically and spectrophotometrically. On the basis of receptor dissolution enthalpies and the literature data, the enthalpies for transfer of reactants and products between the solvents were calculated. The solvent inclusion within a calixarene hydrophobic basket was explored by means of 1H NMR spectroscopy. Classical molecular dynamics of the calixarene ligands and their complexes were carried out as well. The affinity of receptors for cations in methanol and N,N-dimethylformamide was quite similar, irrespective of whether they contained glucose subunits or not. This indicated that sugar moieties did not participate or influence the cation binding. All studied reactions were enthalpically controlled. The peak affinity of receptors for sodium cation was noticed in all complexation media. The complex stabilities were the highest in acetonitrile, followed by methanol and N,N-dimethylformamide. The solubilities of receptors were greatly affected by the presence of sugar subunits. The medium effect on the affinities of calixarene derivatives towards cations was thoroughly discussed regarding the structural properties and solvation abilities of the investigated solvents.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

Inhibition Effects of Some Organic Compounds on Zinc Corrosion in 3.5% NaCl

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Viorel Branzoi ◽  
Alina Pruna ◽  
Florina Branzoi
Keyword(s):  
Organic Compounds ◽  
Electrochemical Impedance ◽  
Corrosion Process ◽  
Diffusion Control ◽  
Cathodic Reaction ◽  
Zinc Electrode ◽  
Electrochemical Studies ◽  
Nacl Solution ◽  
Sodium Dodecylsulphate ◽  
Zinc Corrosion

The inhibition of zinc corrosion in 3.5% NaCl solution by some organic compounds (sodium dodecylsulphate (SDS), sodium dodecylbenzosulphonate (SDBS) and sodium 1,4-bis(2-etylhexyl) sulphosuccinate (AOT)) was investigated. The inhibition efficiencies were determined by polarization measurements of the zinc electrode in the solution. Electrochemical impedance spectroscopy (EIS) was also used for electrochemical studies of zinc electrode in this medium. The results showed that the used surfactants inhibit the cathodic reaction of hydrogen evolution and at low anodic overvoltage the corrosion process is under activation control, while at high anodic overvoltage the process is under diffusion control.

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