ESR measurements of the partitioning of some new spin probes in n-octanol–water

✍ Scribed by Steven E. Bottle; Duncan G. Gillies; Aaron S. Micallef; Damien A. Reid; Leslie H. Sutcliffe

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 92 KB
• Volume: 37
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199910)37:10<730::aid-mrc530>3.0.co;2-e

✦ Synopsis

The stable free radical 1,1,3,3-tetramethylisoindolin-2-yloxyl (TMIO) has proved to be very suitable for use as a spin probe for a number of applications. Because it is soluble mainly in non-polar liquids, there is a need for new derivatives that can be used in a variety of environments. This has been done by introducing substituents in the 5-position of the aromatic ring, namely carboxyl (CTMIO), trimethylamino (TMTMIOI) and sodium sulphonate (NaTMIOS). An accurate ESR method was developed for the measurement of partition coefficients in n-octanol-water. For comparison purposes the method was also applied to some Tempo derivatives. The effect of temperature on the rotational correlation times and the nitrogen-14 hyperfine coupling constant of some of the spin probes was investigated. There is evidence for dimerization of CTMIO to form a biradical.