Electron spin resonance study of the spin label 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl oriented in the inclusion compound 2′-hydroxy-2,4,4,7,4′-pentamethylflavan

Abstract

2′-Hydroxy-2,4,4,7,4′-pentamethylflavan (I) has been found to form a one-to-one inclusion compound with the nitroxide spin label 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl (Tanol). E.s.r. analysis of an inclusion crystal of I with a 1 : 1000 molar mixture of Tanol and the spin label precursor, 2,2,6,6-tetramethyl-4-piperindinol (II) reveals that the nitrogen hyperfine splitting tensor component A_xx= 21.6 ± 0.3 MHz, A_yy= 19.7 ± 0.3 MHz, and A_zz= 101.4 ± 0.5 MHz, while g_xx= 2.0085 ± 0.0001, g_yy= 2.0059 ± 0.0001 and g_zz= 2.0021 ± 0.0001 for Tanol.