Electron-acceptor Centers of Alkali Metal Modified Alumina Studied by the Anthraquinone as a Probe Molecule
Abstract
Anthraquinone paramagnetic complexes have been used to study electron-acceptor centers on the surface of alumina modified with alkali metal ions (Li+, Na+, K+). Complexes have been characterized by CW EPR, ENDOR and pulse EPR (HYSCORE) techniques. It has been shown that alkali metal ions decreased the strength of electron-acceptor centers due to the inductive effect. As a result the concentration of anthraquinone complex with two Lewis acid sites (LAS) decreased, but the concentration of complex with one LAS increased with the increasing of alkali metal content. At large alkali metal concentration other kinds of anthraquinone paramagnetic complexes are formed, that are anthrasemiquinone weakly bound with LAS as well as anthrasemiquinone ion pair with alkali metal cation (lithium).
Keywords
EPR,
ENDOR,
HYSCORE,
electron-acceptor centers,
paramagnetic complexes of anthraquinone,
alumina,
aluminates
Supporting agencies: This work was supported by the Federal Agency on the Science and Innovations (State Contract 02.451.11.7012 of August 29, 2005), the Concil on Grants of the President Of the Russian Federation (Program of State Support for Leading Scientific Schools of the Russian Federation, Grant RI-112/001/056) and the Russian Foundation for Basic Research (Project No. 06-03-32830a).
About the Authors
M. V. Burova
Chemical Department, Moscow State University
Russian Federation
Russian Federation
Moscow
A. V. Fionov
Chemical Department, Moscow State University
Russian Federation
Russian Federation
Moscow
M. Bonora
Department of Physics and Measurement Technology IFM
Sweden
Sweden
Linköping University, S-581 83, Linköping
A. Lund
Department of Physics and Measurement Technology IFM
Russian Federation
Russian Federation
Linköping University, S-581 83, Linköping
V. V. Lunin
Chemical Department, Moscow State University
Russian Federation
Russian Federation
Moscow
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Review
For citations:
Burova M.V., Fionov A.V., Bonora M., Lund A., Lunin V.V. Electron-acceptor Centers of Alkali Metal Modified Alumina Studied by the Anthraquinone as a Probe Molecule. Magnetic Resonance in Solids. 2007;9(1):13-17.
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