Dynamics of pH-sensitive nitroxide radicals in water adsorbed in ordered mesoporous molecular sieves by EPR Spectroscopy

Dynamics of pH-sensitive nitroxide radicals in water adsorbed in ordered mesoporous molecular sieves by EPR Spectroscopy Full article

Journal

Microporous and Mesoporous Materials
ISSN: 1387-1811 , E-ISSN: 1873-3093

Output data

Year: 2013, Volume: 179, Pages: 258-264 Pages count : 7 DOI: 10.1016/j.micromeso.2013.05.019

Tags

Ordered mesoporous materials; PH-sensitive nitroxide radicals; Fast (slow) radical motion; EPR spectroscopy

Authors

Kovaleva Elena G. ¹ , Molochnikov Leonid S. ² , Golovkina Elena L. ² , Hartmann Martin ³ , Kirilyuk Igor.A. ⁴ , Grigor'ev Igor.A. ⁴

Affiliations

1	nstitute of Chemical Engineering, Ural Federal University, Mira St., 19, 620002 Yekaterinburg, Russia
2	Department of Inorganic and General Chemistry, Ural State Forest Engineering University, Siberian Highway, 37, 620100 Yekaterinburg, Russia
3	Erlangen Catalysis Resource Center (ECRC), Friedrich-Alexander Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
4	Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrent’ev Av. 9, 630090 Novosibirsk, Russia

A spin pH probe technique was used to study the influence of the channel diameter on the EPR spectra of pH-sensitive nitroxide radicals (NR) located in the channels of the mesoporous molecular sieves MCM-41 and SBA-15 with diameters ranging from 2.3 to 8.1 nm. From EPR spectra analysis and the results of the NR retention by the mesoporous molecular sieves upon washing with an aqueous KCl solution, the regularities of NR molecular location inside the channels were studied. The obtained dependence of the fraction of the radical molecules in the fast motional regime (with the rotational correlation times, tau(c) = 2 x 10(-11) s-9 x 10(-11)s) in the channels of the mesoporous molecular sieves as a function of pH indicates that both NR in the fast and slow motional regime (with tau(c) = 8 x 10(-9)s-7 x 10(-10)s) may be used for estimation of the solution acidity inside the channels and of the near-surface electrical potential. (C) 2013 Elsevier Inc. All rights reserved.

Kovaleva E.G. , Molochnikov L.S. , Golovkina E.L. , Hartmann M. , Kirilyuk I.A. , Grigor'ev I.A.
Dynamics of pH-sensitive nitroxide radicals in water adsorbed in ordered mesoporous molecular sieves by EPR Spectroscopy

Microporous and Mesoporous Materials. 2013. V.179. P.258-264. DOI: 10.1016/j.micromeso.2013.05.019 WOS Scopus

Full text from publisher

Published print:

Sep 1, 2013

Web of science	WOS:000323689400034
Scopus	2-s2.0-84880517059
OpenAlex	W2016331863