Search results for "Radicals"
showing 10 items of 209 documents
1‑Phenyl-3-(pyrid-2-yl)benzo[e][1,2,4]triazinyl: The First "Blatter Radical" for Coordination Chemistry
2014
A neutral air- and moisture-stable N,N′-chelating radical ligand, 1-phenyl-3-(pyrid-2-yl)benzo[e][1,2,4]triazinyl (1) was synthesized and characterized by electron paramagnetic resonance spectroscopy, X-ray crystallography, and magnetic measurements. Subsequent reaction of 1 with Cu(hfac)2·2H2O (hfac = hexafluoroacetylacetonate) under ambient conditions afforded the coordination complex Cu(1)(hfac)2 in which the radical binds to the metal in a bidentate fashion. Magnetic susceptibility data collected from 1.8 to 300 K indicate a strong ferromagnetic metal-radical interaction in the complex and weak antiferromagnetic radical···radical interactions between the Cu(1)(hfac)2 units. Detailed com…
Comparison of spin density calculation methods for various alkyl-substituted 9,10-anthraquinone anion radicals in the solution phase
1996
EPR and ENDOR spectra were recorded for 2-methyl-9,10-anthraquinone (2-methylAQ), 2-ethylAQ, 2-tertbutylAQ and 2,3-dimethylAQ anion radicals in the solution phase. The EPR spectra were simulated with the help of ENDOR data. The experimental isotropic hyperfine coupling constants (IHFCs) were compared with calculated values from semi-empirical INDO, spin-restricted AM1/CI and B3PW91 density-functional methods. The best computational methods for the IHFCs were the semi-empirical AM1/CI method and the B3PW91 density-functional method with a large basis set.
Lauroyl peroxide as thermal initiator of lauryl methacrylate monolithic columns for CEC
2008
The preparation of lauryl methacrylate (LMA)-based monolithic columns for CEC using lauroyl peroxide (LPO) as thermal initiator of polymerization has been investigated. The influence of initiator amount and composition of porogenic solvent on the physical and electrochromatographic properties of the resulting LMA-based monoliths was evaluated. A comparison with LMA-based columns thermally polymerized with AIBN was performed. At a given porogenic solvent composition, LMA stationary phases initiated with LPO showed higher permeabilities and better efficiency values than those prepared using AIBN as initiator. The optimum polymerization mixture found for LPO initiator provided a minimum plate …
Influence of solvents on the antioxidant property of flavonoids.
2003
In polyphenols redox systems, the solvent plays a fundamental role in the chemical behaviour of these compounds. Antioxidants can react in different ways with the prooxidant molecules. We have found differences in the antioxidant capacity of flavonoids such as naringin, neohesperidin, neoericitrin, hesperidin, narirutin didymin and the related flavones naringenin, hesperetin eriodictyol and isosakuratenin, when they are in the presence of radicals and solved in water or in an alcohol mixture.
Vibronic structure in triatomic molecules : The hydrocarbon flame bands of the formyl radical (HCO). A theoretical study
1998
A theoretical study of the vibrational structure of the math 2A′ ground and math 2A′ excited states of the formyl radical, HCO, and its deuterated form, DCO, has been performed. The potential energy surfaces have been computed by means of a multiconfigurational perturbative method, CASPT2. The computed geometries and the harmonic and anharmonic frequencies are successfully compared to the available experimental information. The vibrational intensities of the transition math 2A′↔math 2A′ have been computed both for absorption and emission. The results lead to accurate determinations of several structural parameters and some reassignments of the vibrational transitions of the so-called hydroc…
Does catalase play a role in Adriamycin induced cardiotoxicity?
1980
Summary Adriamycin causes an increase of lipid peroxidation in mouse cardiac homogenates that is dependent on the concentration of the antiblastic. The same phenomenon is not observed in the hearts of mice treated with an elevated dose of Adriamycin in which, conversely, an increase of the antioxidizing enzyme catalase was noticed. The significance of these findings is discussed with relationship to the hypothesis of an enhanced free radicals formation at the basis of Adriamycin induced cardiotoxicity.
Versuche zum Vorgang der Wasserstoffübertragung, XI. Isomerisierung Definiert Deuterierter Alkylbenzole an Raney-Nickel
1964
α-Deutero-toluol. o-, m- und p-Deutero-toluol sowie β-Deutero-athylbenzol isomerisieren schon bei 20° in Beruhrung mit wasserfreiem Raney-Nickel. Der Deuterium-Gehalt des Substrates bleibt dabei annahernd konstant. Beim α-Deutero-toluol wandern mehr als 50% des Deuteriums aus der Seitenkette in den Kern, wobei es sich weitgehend auf die gleichen Positionen verteilt wie beim Austausch von leichtem Toluol mit Deuterium-Gas an Raney-Nickel. Der aromatische Kern wird unter diesen Bedingungen nicht abgesattigt. Mit Hilfe der Massenspektrographie kann gezeigt werden, das Deuterium auch zwischenmolekular ausgetauscht wird. — Im Toluol kernstandiges Deuterium verteilt sich an Raney-Nickel auf samtl…
Gas phase behavior of radical cations of perfluoroalkyl-1,2,4-triazines: an experimental and theoretical study
2009
Electron ionization mass spectrometry and low-energy collision-induced decomposition reactions occurring in a tridimensional ion trap, together with density functional theory (DFT) calculations on neutrals, even- and odd-electron cations, have been used to study the gas-phase ion chemistry of a series of perfluoroalkyl-1,2,4-triazines. Loss of oxygen, due to thermal degradation occurring before ionization, likely involving the hydroxylamino group, has been observed. Compounds having a carbonyl group at position 6 of the triazine ring fragment in the source by elimination of NO followed by HF or CO. The decomposition pathways occurring due to CID experiments have shown interesting features d…
Impact of electron beam irradiation on fish gelatin film properties
2016
International audience; The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino aci…
A synergic nanoantioxidant based on covalently modified halloysite–trolox nanotubes with intra-lumen loaded quercetin
2016
We describe the preparation and properties of the first example of a synergic nanoantioxidant, obtained by different functionalizations of the external surface and the inner lumen of halloysite nanotubes (HNTs). Trolox, a mimic of natural α-tocopherol, was selectively grafted on the HNT external surface; while quercetin, a natural polyphenolic antioxidant, was loaded into the inner lumen to afford a bi-functional nanoantioxidant, HNT–Trolox/Que, which was investigated for its reactivity with transient peroxyl radicals and a persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH˙) radical in comparison with the corresponding mono-functional analogues HNT–Trolox and HNT/Que. Both HNT–Trolox and HNT/Q…