ESR Study (esr + study)

Distribution by Scientific Domains


Selected Abstracts


Spin Divergence Induced by Exohedral Modification: ESR Study of Sc3C2@C80 Fulleropyrrolidine,

ANGEWANDTE CHEMIE, Issue 10 2010
Taishan Wang Dr.
Die paramagnetischen Eigenschaften des endohedralen Fullerens Sc3C2@C80 können durch exohedrale Modifizierung des Käfigs mithilfe der Prato-Reaktion verändert werden (siehe Bild). Eine Analyse der Spindichteverteilungen und Endoclusterdynamik offenbart die paramagnetischen Eigenschaften des Sc3C2@C80 -Fulleropyrrolidins und bietet einen Einblick in das Addenden-abhängige paramagnetische Verhalten endohedraler Fullerene. [source]


XAS, ESR and Potentiometric Studies of Three Dinuclear N,N, -para -Xylylenebis(tetraazamacrocycle)copper(II) Complexes , X-ray Crystal Structure of [N,N,- p -Xylylenebis(cyclen)]copper(II)

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2003
Mathieu Soibinet
Abstract Dicopper complexes with N,N, - p -xylylenebis(cyclam or cyclen) and with the heteroditopic N,N, - p -xylylenebis(cyclam-cyclen) were synthesized. An X-ray study of the N,N, - p -xylylenebis(cyclen)dicopper complex showed that the copper(II) ion is five-coordinate with an H2O molecule in apical position. With this ligand, a polymeric chain was also obtained in the presence of KSCN. The terminal donor atoms of the bridging NCS, anion are coordinated in apical position to the square-pyramidal copper(II) ion. Two alternating kinds of Cu2L4+ moieties are present in the chain, the first with two N4S chromophores and the second with two N5 chromophores. EXAFS and XANES results are in agreement with a five-coordinate copper ion in the cyclen unit and a six-coordinate copper ion in the cyclam unit. Thermodynamic constants were determined by potentiometry. The existence of dinuclear Cu2L4+ species (ligand/metal ratio < 1) and mononuclear CuLHn(2+n)+ species (ligand/metal ratio > 1) were confirmed by an ESR study at variable pH. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


In situ ESR study of gold supported on NaY zeolite

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009
Z. Qu
Abstract Electron spin resonance (ESR) spectroscopy was used to study the anchoring of a Au complex and gold nanoparticles in NaY type zeolites. The complex of Au(II) with two nitrogen atoms of two ethylenediamine ligands [giso = 2.053, A (Au) = 16.4 G, A (N) = 15.0 G.] in the supercage of the zeolite and conduction electron spin resonance (CESR) of gold particles with 1.56-nm diameter (g = 2.064) were observed. Their formation and stability were related with the gold concentration and the pre-treatment conditions. The small gold particles stabilized in the supercage of zeolite were formed in the samples with low gold concentration after oxygen pre-treatment. The confinement in the zeolite pores obviously prevents the Au(II) complex bound to two nitrogen ligands from undergoing disproportionation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]


ESR/DFT study of bis-iminophosphorane cation radicals

MAGNETIC RESONANCE IN CHEMISTRY, Issue 12 2007
Adil Matni
Abstract Bis-iminophosphoranes containing various types of linkers between two R3PN moieties were electrochemically oxidized at controlled potential in situ in the electron spin resonance (ESR) cavity. For linkers constituted of phenylenes, conjugated phenylenes or merely a dicyanoethylenic bond, this oxidation led to well-resolved ESR spectra which were characterized by their g values and by their 1H, 14N and 31P isotropic hyperfine constants. These coupling constants agree with those calculated by DFT for the corresponding cation radicals. Experimental and theoretical results clearly indicate that in these species the unpaired electron is mostly delocalized on the bridge and on the nitrogen atoms while the spin density on the phosphorus atoms is particularly small. Cyclic voltammetry and ESR spectra show that the nature of the bridge between the two iminophosphoranes considerably influences the oxidation potential of the compound as well as the stability of the radical cation. Information about the conformation of the precursor containing two Ph3PN moieties separated by a C(CN)C(CN)group was obtained from its crystal structure. Copyright © 2007 John Wiley & Sons, Ltd. [source]