Unusual Redox Behavior of .alpha.-Oligoheteroaromatic Compounds: An Increasing First Oxidation Potential with Increasing Conjugation Length

1995 ◽  
Vol 7 (10) ◽  
pp. 1984-1989 ◽  
Author(s):  
J. A. E. H. van Haare ◽  
L. Groenendaal ◽  
H. W. I. Peerlings ◽  
E. E. Havinga ◽  
J. A. J. M. Vekemans ◽  
...  
Keyword(s):  
Oxidation Potential ◽  
Redox Behavior ◽  
Conjugation Length

Synthesis, physicochemical properties and antimicrobial activity of mono-/dinitroxyl amides

2014 ◽  
Vol 12 (25) ◽  
pp. 4491-4502 ◽  
Author(s):  
Miroslav Kavala ◽  
Vlasta Brezová ◽  
Ľubomír Švorc ◽  
Zuzana Vihonská ◽  
Petra Olejníková ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Physicochemical Properties ◽  
Oxidation Potential ◽  
Redox Behavior ◽  
Reversible Redox

Novel TEMPO and PROXYL derivatives reveal (quasi)reversible redox behavior. The EWG-substituents increase their oxidation potential in comparison to the EDG-groups. Unlike pyrrolidinyl derivatives, the piperidinyl nitroxides inhibit the growth of Staphylococcus sp.

Oligo(phenylenevinylene)s end-capped with phenothiazine or triphenylamine

2003 ◽  
Vol 771 ◽  
Author(s):  
H. Detert ◽  
O. Sadovski
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Electronic Spectra ◽  
Oxidation Potential ◽  
Side Chains ◽  
Optical And Electrical Properties ◽  
Conjugation Length ◽  
Electrical And Optical Properties ◽  
End Groups ◽  
Electronic Character

AbstractMonodisperse oligo(phenylenevinylene)s end-capped with arylamines have been prepared via Horner Olefinations from bisphosphonates and arylaminobenzaldehydes. The influences of the conjugation length, different arylamine end groups, and of side chains with various electronic character on the electrical and optical properties of the chromophores are investigated. The elongation of the π-conjugated segment from 3 to 5 rings gives rise to bathochromic shifts of the electronic spectra and a slight increase of the oxidation potential. The same but more pronounced is true when the central electron donating ethers are replaced by the strong acceptor alkylsulfone. The electronic spectra of chromophores with triphenylamine and with N-alkylphenothiazines as end groups are quite similar, but the heterocyclic unit reduces the oxidation potential. The incorporation of a chromophor into a segmented copolymer has only negligible effect on the optical and electrical properties.

The oxidation of Inconel alloy MA754 at low oxidation potential

1983 ◽  
Vol 41 ◽  
pp. 218-219
Author(s):  
D. N. Braski ◽  
P. D. Goodell ◽  
J. V. Cathcart ◽  
R. H. Kane
Keyword(s):  
Surface Layer ◽  
Oxidation Potential ◽  
Metal Interface ◽  
Elevated Temperature Strength ◽  
Surface Conditions ◽  
Inconel Alloy ◽  
Inco Alloy ◽  
Resistance To Oxidation ◽  
Oxide Particles ◽  
Cold Worked

It has been known for some time that the addition of small oxide particles to an 80 Ni—20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied collaboratively by ORNL and INCO Alloy Products Company.Initial experiments were performed using INCONEL alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y2O3 (wt %).Small disks (3 mm diam × 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 μm diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000°C. Three different environments were investigated: hydrogen with nominal dew points of 0°C, —25°C, and —55°C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

Assessment of Self-Heating Susceptibility of Indian Coal Seams – A Neural Network Approach

2014 ◽  
Vol 59 (4) ◽  
pp. 1061-1076 ◽  
Author(s):  
D.C. Panigrahi ◽  
S.K. Ray
Keyword(s):  
Neural Network ◽  
Spontaneous Combustion ◽  
Potential Method ◽  
Oxidation Potential ◽  
Wet Oxidation ◽  
Experimental Conditions ◽  
Neural Network Approach ◽  
Indian Coal ◽  
Petrographic Analyses ◽  
Artificial Neural Network Ann

Abstract The paper addresses an electro-chemical method called wet oxidation potential technique for determining the susceptibility of coal to spontaneous combustion. Altogether 78 coal samples collected from thirteen different mining companies spreading over most of the Indian Coalfields have been used for this experimental investigation and 936 experiments have been carried out by varying different experimental conditions to standardize this method for wider application. Thus for a particular sample 12 experiments of wet oxidation potential method were carried out. The results of wet oxidation potential (WOP) method have been correlated with the intrinsic properties of coal by carrying out proximate, ultimate and petrographic analyses of the coal samples. Correlation studies have been carried out with Design Expert 7.0.0 software. Further, artificial neural network (ANN) analysis was performed to ensure best combination of experimental conditions to be used for obtaining optimum results in this method. All the above mentioned analysis clearly spelt out that the experimental conditions should be 0.2 N KMnO4 solution with 1 N KOH at 45°C to achieve optimum results for finding out the susceptibility of coal to spontaneous combustion. The results have been validated with Crossing Point Temperature (CPT) data which is widely used in Indian mining scenario.

Recent advances in the Silver catalysed synthesis of furan and its applications

2020 ◽  
Vol 09 ◽  
Author(s):  
C M A Afsina ◽  
Mohan Neetha ◽  
Thaipparambil Aneeja ◽  
Gopinathan Anilkumar
Keyword(s):  
Organic Synthesis ◽  
Oxidation Potential ◽  
Silver Complexes ◽  
Wide Spread ◽  
Silver Catalysts ◽  
Recent Advances ◽  
High Oxidation ◽  
Furan Moiety ◽  
Anti Fungal ◽  
Fragrance Compounds

: Furan and its derivatives find wide-spread application as pharmaceuticals, pigments, dyes, brighteners, flavour & fragrance compounds and insecticides. They also exhibit anti-hyperglycemic, analgesic, anti-inflammatory, antibacterial, anti-fungal and anti-tumour activities. Silver catalysts are nowadays commonly used in organic synthesis due to the high oxidation potential and versatile nature of silver complexes. In this review, we summarise the recent advances in the synthesis and applications of furan moiety using silver catalysis and covers literature from 2015-2020.

Effects of Doping on the Electrochemical and Electrical Properties of Poly(2,5-di(2-thienyl)pyrrole)

1999 ◽  
Vol 64 (8) ◽  
pp. 1357-1368 ◽  
Author(s):  
Enric Brillas ◽  
José Carrasco ◽  
Ramon Oliver ◽  
Francesc Estrany ◽  
Víctor Ruiz
Keyword(s):  
Mass Spectrometry ◽  
Fast Atom Bombardment ◽  
Oxidation Potential ◽  
Ethanolic Solution ◽  
Pt Electrode ◽  
Reversible Process ◽  
Oxidation Potentials ◽  
Lower Productivity ◽  
Polymeric Chains ◽  
Linear Molecules

The electropolymerization of 2,5-di(2-(thienyl)pyrrole) (SNS) on a Pt electrode from ethanolic solution with LiClO4 or LiCl as electrolyte has been studied by cyclic voltammetry (CV) and chronoamperometry (CA). In both media, a quasi-reversible process has been indicated by CV, reversing the scan at low oxidation potentials. Under these conditions, reducible positive charges formed in both oxidized polymers are compensated by the entrance of anions from solution. Elemental analysis reveals that polymers generated at a low oxidation potential by CA contain a 21.03% (w/w) of ClO4- or a 9.56% (w/w) of Cl-. The poly(SNS) doped with Cl- presents higher proportion of reducible positive charges, higher polymerization charge and lower productivity. A much higher electrical conductivity, however, has been found for the poly(SNS) doped with ClO4-. Both polymers are soluble in DMSO, acetone and methanol. The dimer, trimer, tetramer and pentamer have been detected as soluble and neutral linear oligomers by mass spectrometry-fast atom bombardment. The analysis of polymers by infrared spectroscopy confirms the predominant formation of linear molecules with α-α linkages between monomeric units. A condensation mechanism involving one-electron oxidation of all electrogenerated linear and neutral polymeric chains is proposed to explain the SNS electropolymerization.

scholarly journals Understanding the role of conjugation length on the self-assembly behaviour of oligophenyleneethynylenes

2021 ◽  
Author(s):  
Beatriz Matarranz ◽  
Goutam Ghosh ◽  
Ramesh Kandanelli ◽  
Angel Sampedro ◽  
Kalathil K. Kartha ◽  
...  
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Conjugation Length ◽  
The Relationship

We unravel the relationship between conjugation length and self-assembly behaviour of oligophenyleneethynylenes (OPEs).

scholarly journals Fine-Tuning the Biological Profile of Multitarget Mitochondriotropic Antioxidants for Neurodegenerative Diseases

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 329
Author(s):  
Daniel Chavarria ◽  
Ophelie Da Silva ◽  
Sofia Benfeito ◽  
Sandra Barreiro ◽  
Jorge Garrido ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Antioxidant Properties ◽  
Neuroblastoma Cells ◽  
Oxidation Potential ◽  
Fine Tuning ◽  
Mitochondrial Oxidative Stress ◽  
Electric Eel ◽  
Ic50 Values ◽  
System Extension ◽  
Inhibition Potency

Neurotransmitter depletion and mitochondrial dysfunction are among the multiple pathological events that lead to neurodegeneration. Following our previous studies related with the development of multitarget mitochondriotropic antioxidants, this study aims to evaluate whether the π-system extension on the chemical scaffolds of AntiOXCIN2 and AntiOXCIN3 affects their bioactivity and safety profiles. After the synthesis of four triphenylphosphonium (TPP+) conjugates (compounds 2–5), we evaluated their antioxidant properties and their effect on neurotransmitter-metabolizing enzymes. All compounds were potent equine butyrylcholinesterase (eqBChE) and moderate electric eel acetylcholinesterase (eeAChE) inhibitors, with catechols 4 and 5 presenting lower IC50 values than AntiOXCIN2 and AntiOXCIN3, respectively. However, differences in the inhibition potency and selectivity of compounds 2–5 towards non-human and human cholinesterases (ChEs) were observed. Co-crystallization studies with compounds 2–5 in complex with human ChEs (hChEs) showed that these compounds exhibit different binging modes to hAChE and hBChE. Unlike AntiOXCINs, compounds 2–5 displayed moderate human monoamine oxidase (hMAO) inhibitory activity. Moreover, compounds 4 and 5 presented higher ORAC-FL indexes and lower oxidation potential values than the corresponding AntiOXCINs. Catechols 4 and 5 exhibited broader safety windows in differentiated neuroblastoma cells than benzodioxole derivatives 2 and 3. Compound 4 is highlighted as a safe mitochondria-targeted antioxidant with dual ChE/MAO inhibitory activity. Overall, this work is a contribution for the development of dual therapeutic agents addressing both mitochondrial oxidative stress and neurotransmitter depletion.

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