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Complex Exhibiting (complex + exhibiting)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Hydrogen-bonding effects on electronic g -tensors of semiquinone anion radicals: Relativistic density functional investigation

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4-5 2002
Konstantin M. Neyman
Abstract We report results of systematic g -tensor calculations of hydrogen-bonded complexes of two benchmark semiquinone anion radicals, 1,4 -benzoquinone and tetramethyl- 1,4 -benzoquinone (duroquinone), with water and methanol molecules. The calculations have been carried out with the help of a recently developed g -tensor module that is based on a relativistic density functional method that takes spin,orbit interaction self-consistently into account. We demonstrate the applicability of this new computational scheme to describe quantitatively delicate effects of hydrogen bonding on electronic g -tensor values. Also, we explored general trends of how g -tensors depend on the structure and stoichiometry of hydrogen-bonded semiquinone complexes. Complexes exhibiting one hydrogen bond per oxygen atom of the quinones with a linear arrangement of the CO , H moieties were shown to feature g-shifts induced by these hydrogen bonds that are in close agreement with measured electron paramagnetic resonance data. Based on deviations of calculated and measured g-components, we classify all other model complexes studied as less probable under the experimental conditions. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source]

Di-,-oxido-bis{bis[N,N,-bis(2-pyridylmethyl)ethane-1,2-diamine]manganese(III,IV)} tris(perchlorate) hexahydrate: clarification of an order,disorder phase transition

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2009
Anne Nielsen
The title compound, [Mn2O2(C14H18N4)2](ClO4)3·6H2O, contains a mixed-valent MnIII/MnIV complex. In accordance with a previous report [Collins, Hodgson, Michelsen & Towle (1987). J. Chem. Soc. Chem. Commun. pp. 1659,1660], the structure at 295,K is best described in the space group C2/c, with the complex exhibiting twofold rotational symmetry, and with half site occupancy for one perchlorate anion and several solvent water molecules. At 180,K, the structure is ordered in the subgroup P21/n and is clearly shown to be a hexahydrate, rather than the previously reported trihydrate. The origin of the order,disorder phase transition lies in the thermal motion of the perchlorate anions. [source]

Characterization of the G-quadruplex structure of a catalytic DNA with peroxidase activity

BIOPOLYMERS, Issue 5 2009
De-Ming Kong
Abstract It has been reported that the complexes formed by hemin and some G-quadruplexes can be developed as a new class of DNAzyme with peroxidase activity. This kind of DNAzyme has received a great deal of attention. But to date, the actual G-quadruplex structure that can provide hemin with enhanced peroxidase activity is in doubt. Herein, the G-quadruplex structure of CatG4, a 21-nucleotide DNA oligomer which was previously reported to bind hemin and the resulting complex exhibiting enhanced peroxidase activity, was characterized by fluorescence and circular dichroism measurements. The results suggest that the catalytically active form of CatG4 may be a unimolecular parallel quadruplex rather than a unimolecular chair-type antiparallel quadruplex or a multistranded parallel quadruplex. In addition, the fluorescence analysis of labeled oligonucleotides may be developed as a supplementary tool for the study of DNA conformations. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 331,339, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

The impact of ion pair association upon the 1H NMR spectra of cationic complexes akin to Grubbs catalysts,

MAGNETIC RESONANCE IN CHEMISTRY, Issue 4 2010
Günter Paulus Schiemenz
Abstract A reconsideration of the 1H NMR spectra of cationic transition metal complexes exhibiting the features of cyclophanes on the basis of Mislow's classification of topic groups arrives at the conclusion that the spectral changes triggered by chiral counterions reflect an intracationic diastereotopication of enantiotopic protons rather than the existence of pairs of long-lived diastereomeric ion pairs. Copyright © 2010 John Wiley & Sons, Ltd. [source]