Anisotropic reorientation of planar molecules measured by nuclear relaxation in strongly coupled spin systems

摘要

In this paper we describe the use of nuclear magnetic relaxation in strongly coupled spin systems for determining all three rotational diffusion constants of rigid, planar molecules withC2vsymmetry. The complete evaluation of the motional parameters rests on the accurate measurement of the crosshyphen;correlation terms relating the reorientation of two protonndash;proton internuclear vectors. This term, as well as more familiar auto correlation terms, may be extracted from an analysis of the recovery of individual lines in the strongly coupled proton spin system following a nonselective 180deg; pulse. The principles, procedure, and practical considerations of this approach to studies of anisotropic motion are illustrated for theAB2spin systems of 1,2,3hyphen;trichlorobenzene, 2,6hyphen;dichloroanisole, and 2,6hyphen;dichlorophenolhyphen;0hyphen;d.