Aliaga, Carolina; Bravo-Moraga, Felipe; Gonzalez-Nilo, Danilo; Marquez, Sebastian; Luehr, Susan; Mena, Geraldine; Caroli Rezende, Marcos
Location of TEMPO derivatives in micelles: subtle effect of the probe orientation
FOOD CHEMISTRY, 192:395-401, FEB 1 2016

Partition coefficients for six 4-substituted derivatives of the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) derivatives in aqueous solutions of reduced Triton X-100 (RTX-100) were determined by measurements of the probe EPR g-factor and of the fluorescence quenching of pyrene by the radical in the micelle. The partition constant attained a maximum value and then decreased with increasing probe hydrophobicity. Simulation of the probes inside the micelle showed that this trend could be rationalized by a change in the orientation of the 4-substituted TEMPO derivatives with the increasing substituent. chain-length. The use of the EPR g-factor for the determination of partition constants of radicals in micellar systems was thus validated as a reliable and sensitive method, capable of describing the probe orientation in its microenvironment. (C) 2015 Elsevier Ltd. All rights reserved.


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