Proton spin-lattice relaxation studies. N-aryl-1-isoindolinones

Proton spin-lattice relaxation rates (R₁ values) have been measured, at 270 MHz, for a series of N-aryl isoindolinones. A normalization procedure has been used to enable comparison of R₁ values in different compounds by minimizing the effects on relaxation rates of changes in motional correlation times accompanying changes in substitution patterns. A substantial (4.3-fold) dynamic range of R₁ values has been observed, and individual values have been correlated with the molecular environments of the nuclei. There is evidence for an interring relaxation process.