SEGMENTAL MOTION IN PSEUDOMONIC ACID A: A CARBON-13 SPIN-LATTICE RELAXATION TIME STUDY AT TWO FIELD STRENGTHS

Abstract

The mobility of pseudomonic acid A in dimethyl sulfoxide-d₆ solution has been determined from ¹³C spin-lattice relaxation time measurements at two field strengths. The central tetrahydropyran ring reorientates isotropically with a rotational correlation time of ¿ 280 picoseconds/radian. Both side-chains exhibit marked segmental motion with correlation times decreasing to only - 50 picoseconds/radian at the end of the nonanoic acid side-chain.