Use of 1,4-bis(2,2,6,6-tetramethyl-1-oxyl-4-piperidyl)butane as a probe for studying acid sites
ESR spectroscopy was applied to study paramagnetic complexes of the nitroxyl biradical of 1,4-bis(2,2,6,6-tetramethyl-1-oxyl-4-piperidyl)butane formed with AlCl3 in a toluene solution and resulted from the interaction with the acid sites on the SiO2 and γ-Al2O3 surface. This biradical in solution forms a complex with two AlCl3 molecules, and a complex with two hydroxyl groups is formed on the SiO2 surface. When the biradical is adsorbed on the γ-Al2O3 surface, complex formation is complicated because of steric hindrance preventing bidentate coordination.
Key words1,4-bis(2,2,6,6-tetramethyl-1-oxyl-4-piperidyl)butane paramagnetic complexes aluminum chloride silica alumina electron paramagnetic resonance
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