Please use this identifier to cite or link to this item: https://elar.usfeu.ru/handle/123456789/9064
Title: Interfacial Electrostatic Properties of Hydrated Mesoporous and Nanostructured Alumina Powders by Spin Labeling EPR
Authors: Kovaleva, E. G.
Molochnikov, L. S.
Stepanova, D. P.
Pestov, A. V.
Trofimov, D. G.
Kirilyuk, I. A.
Smirnov, A. I.
Issue Date: 2017
Publisher: Humana Press Inc.
Citation: Kovaleva, E. G. Interfacial Electrostatic Properties of Hydrated Mesoporous and Nanostructured Alumina Powders by Spin Labeling EPR / E. G. Kovaleva, L. S. Molochnikov, D. P. Stepanova [et al.] // Cell Biochemistry and Biophysics. – 2017. – Vol. 75. – Iss. 2. – P. 159-170.
Abstract: Acid-base equilibria and interfacial electrostatic properties of hydrated mesoporous and nanostructured alumina powders are determining factors for the use of these materials in heterogeneous catalysis and as a sorption media for filtration and chromatographic applications including life sciences. Here spin probe electron paramagnetic resonance spectroscopy of pH-sensitive nitroxides was employed to evaluate the surface charge and interfacial acid-base equilibria at the pore surface of mesoporous powders of α-Al2O3, γ-Al2O3, Al2O3 × nH2O, and basic γ-Al2O3 and nanostructured Al2O3 in the form of pristine materials and modified with aluminum-tri-sec-butoxide, hydroxyaluminum glycerate, and several phospholipids. A new pH-sensitive nitroxide probe, 4-dimethylamino-5,5-dimethyl-2-(4-(chloromethyl)phenyl)-2-ethyl-2,5-dihydro-1H-imidazol-1-oxyl hydrochloride semihydrate (nitroxide R1), has been synthesized and characterized. It was found that conditions of preparation of alumina powders exert strikingly large effects on the apparent pKa of nitroxides measured from electron paramagnetic resonance titration curves. Specifically, while the electron paramagnetic resonance titrations curves for the nitroxide R1 in mesoporous powders prepared from basic γ-Al2O3 and Al2O3 × nH2O were shifted by ΔpKa≈ +0.6 and up to ≈ +1.2 pH units respectively, the shift for γ-Al2O3 was found to be much higher: ΔpKa = +3.5. Assuming approximately the same ∆pH = 0.5–1.0 arising from a difference in the hydrogen ion activity between the bulk solution phase and that in a confined pore volume, the samples were ranked in the following order of descending magnitude of the effective surface electrostatic potential Ψ: mesoporous γ-Al2O3 > Al2O3 × nH2O > basic γ-Al2O3 > α-Al2O3. Conditions of the Al2O3 synthesis as well as the surface modification procedures were found to have profound effects on the interfacial electrostatic properties of hydrated samples that are likely related to the nature and concentration of the active sites on the alumina surfaces. © 2016, Springer Science+Business Media New York.
Keywords: ALUMINUM ALKOXIDES
MESOPOROUS ALUMINA
PH-SENSITIVE NITROXIDES
PHOSPHOLIPIDS
ALUMINUM OXIDE
MOLECULAR PROBE
NANOMATERIAL
NITROGEN OXIDE
NITROXYL
PHOSPHOLIPID
POWDER
SPIN LABEL
CHEMISTRY
ELECTRON SPIN RESONANCE
MOLECULAR PROBE
PH
POROSITY
POWDER
STATIC ELECTRICITY
SURFACE PROPERTY
SYNTHESIS
ULTRASTRUCTURE
ALUMINUM OXIDE
ELECTRON SPIN RESONANCE SPECTROSCOPY
HYDROGEN-ION CONCENTRATION
MOLECULAR PROBES
NANOSTRUCTURES
NITROGEN OXIDES
PHOSPHOLIPIDS
POROSITY
POWDERS
SPIN LABELS
STATIC ELECTRICITY
SURFACE PROPERTIES
URI: https://elar.usfeu.ru/handle/123456789/9064
DOI: 10.1007/s12013-016-0767-0
SCOPUS: 2-s2.0-84994323104
WoS: WOS:000400867700003
RSCI: 31014161
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

Files in This Item:
File Description SizeFormat 
2-s2.0-84994323104.pdf2,4 MBAdobe PDFView/Open    Request a copy


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.