Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbVPh3 type

Smolyaninov, I. V.; Antonova, N. A.; Poddel’sky, Andrey I.; Smolyaninova, S. A.; Осипова, В. П.; Берберова, Н. Т.

doi:10.1016/j.jorganchem.2011.04.004

Cited by 34 publications

(27 citation statements)

References 69 publications

(59 reference statements)

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“…3, curves 2 and 3). In our previous work [2] we observed cyclic alterations in the concentration of LOOH: accumulation gave place to decomposition. Such alterations are caused by spiroendoperoxides formed in aerobic conditions and acting as promotors of lipid peroxidation.…”

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confidence: 73%

“…Previously we showed that the redox characteristics, antiradical activity of organo-antimony(V) complexes with redox-active ligands, as well as their ability to bind molecular oxygen depends on a variety of factors [1][2][3][4][5][6]. Electron-donating substituent group in the redox-active fragment facilitates O 2 binding, shifts anodic oxidation potentials to the cathodic region, and enhances the antiradical activity of Sb(V) compounds [7,8].…”

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confidence: 99%

“…In [2,8] we showed that triphenylantimony(V) complexes with redox-active ligands exhibit pronounced antiradical activity and revealed a reverse correlation between inhibitory activity and oxidation potential. To provide further evidence for such correlation, in the present work we studied the antiradical activity of complexes I-III and 3,6-di-tertbutyl-4,5-dimethoxy-о-benzoquinone in the autooxidation of oleic acid at 60°С.…”

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confidence: 99%

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Redox transformations and antiradical activity of triarylantimony(V) 3,6-di-tert-butyl-4,5-dimethoxycatecholates

et al. 2014

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Triarylantimony(V) catecholate complexes were synthesized by the oxidative addition of 3,6-ditert-butyl-4,5-dimethoxy-o-benzoquinone to triarylstibines. The electrochemical properties and antiradical activity of the synthesized compounds were studied. According to cyclic viltammetry data, the complexes are oxidized via two consecutive quasi-reversible stages. Introduction of halogen atoms in para-position of phenyl groups at Sb(V) causes anodic shifts of the oxidation potentials and enhances stability of the mono-and dicationic forms of the compounds, which form in the course of electrochemical transformations. Triarylantimony(V) catecholate complexes exhibit appreciable antiradical activity in the auto-oxidation of oleic acid. In was found that the inhibitory activity of the complexes depends on their redox potential.Previously we showed that the redox characteristics, antiradical activity of organo-antimony(V) complexes with redox-active ligands, as well as their ability to bind molecular oxygen depends on a variety of factors [1-6]. Electron-donating substituent group in the redox-active fragment facilitates O 2 binding, shifts anodic oxidation potentials to the cathodic region, and enhances the antiradical activity of Sb(V) compounds [7,8]. Electron withdrawing groups in the catecholate ligand increase the potentials of the catecholate-о-semiquinolate-о-benzoquinone redox transitions and sometimes alter the mechanism of electrochemical oxidation of triphenylantimony(V) catecholate complexes from a two-stage one-electron transfer to one-stage two-electron transfer process [9, 10]. The stability of the cationic complexes resulting from electrochemical oxidation is also affected by the nature of the heteroatoms forming five-membered N, O,Oor S,. The properties of Sb(V) catecholate complexes can also be varied not only by varying substituents in the redox-active ligand, but also by functionalizing groups linked to the central antimony atom [15]. In the present work we continued to study the effect of aryl substituents (phenyl, pchlorophenyl, p-fluorophenyl) in the organometallic fragment SbR 3 of triarylantimony(V) 3,6-di-tert-butyl-4,5-dimethoxycatecholate complexes on the electrochemical transformations and antiradical activity in the auto-oxidation of oleic acid.We have synthesized triphenylantimony, tri-pchlorophenyl-, and tri-p-chlorophenylantimony catecholate complexes I-III by the oxidative addition of the corresponding triarylstibines to 3,6-di-tert-butyl-4,5-dimethoxy-о-benzoquinone (Scheme 1).Complex I was described in [5]. Complexes II and III were characterized by 1 H and 13 C NMR spectroscopy and mass spectrometry; their structure was found to be consistent with the suggested formulas. The oxidation potential relates to the reducing ability of a compound and is a factor which allows one to predict the antiradical activity. The electrochemical

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Redox transformations and antiradical activity of triarylantimony(V) 3,6-di-tert-butyl-4,5-dimethoxycatecholates

et al. 2014

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“…The well-characterized spectrum of crystalline DPPH has been used as a standard for g-factor determination [1] and for spectrometer performance evaluation [2]. In solution, DPPH has been used as a radical scavenger for kinetics measurements and to probe radical efficiencies [3] and for dynamic nuclear polarization (DNP) to enhance NMR signals [4]. Although it is one of the most extensively studied radicals in EPR, its electron spin relaxation times have been studied predominantly for samples with high concentrations, in the range of 3 to 140 mM, as is typical for DNP experiments.…”

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Temperature Dependence of Electron Spin Relaxation of 2,2-Diphenyl-1-Picrylhydrazyl in Polystyrene

Meyer

2012

Appl Magn Reson

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The electron spin relaxation rates for the stable radical DPPH (2,2-diphenyl-1-picrylhydrazyl) doped into polystyrene were studied by inversion recovery and electron spin echo at X-band and Q-band between 20 and 295 K. At low concentration (340 μM, 0.01%) spin-lattice relaxation was dominated by the Raman process and a local mode. At high concentration (140 mM, 5%) relaxation is orders of magnitude faster than at the lower concentration, and 1/T1 is approximately linearly dependent on temperature. Spin lattice relaxation rates are similar at X-band and Q-band. The temperature dependence of spin echo dephasing was faster at about 140 K than at higher or lower temperatures, which is attributed to a wagging motion of the phenyl groups.

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“…4, 5 The biolog ical activity of these compounds has been studied. [6][7][8] Antimony compounds are characterized by a diversity of coordination modes and structure types. In the absence of strong steric hindrance, pentacoordinate Sb V deriva tives are prone to complete the coordination number to six through intermolecular interactions or through the coor dination by additional neutral ligands.…”

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Complex of triphenylantimony(v) catecholate with 5-(2,6-dimethylphenyl)-3-(4-pyridyl)-1-phenylformazan

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The complex of triphenylantimony(V) 3,6 di tert butylcatecholate with 5 (2,6 dimethyl phenyl) 3 (4 pyridyl) 1 phenylformazan was synthesized and characterized by spectroscopic and electrochemical methods and by X ray diffraction. In the crystal structure, there are inter molecular hydrogen bonds between the formazan ligands of adjacent molecules. The electro chemical transformations of the complex were investigated by cyclic voltammetry. It was shown that both the formazan and catecholate moieties are involved in redox processes.

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Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbVPh3 type

Cited by 34 publications

References 69 publications

Redox transformations and antiradical activity of triarylantimony(V) 3,6-di-tert-butyl-4,5-dimethoxycatecholates

Redox transformations and antiradical activity of triarylantimony(V) 3,6-di-tert-butyl-4,5-dimethoxycatecholates

Temperature Dependence of Electron Spin Relaxation of 2,2-Diphenyl-1-Picrylhydrazyl in Polystyrene

Complex of triphenylantimony(v) catecholate with 5-(2,6-dimethylphenyl)-3-(4-pyridyl)-1-phenylformazan

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