Studies on Chloroplast Membranes. I. 13C Chemical Shifts and Longitudinal Relaxation Times of Carboxylic Acids

Abstract

The 13C chemical shift and longitudinal relaxation time (T1) of the individual carbon atoms in a series of carboxylic acids in CDCl3 solution have been determined. Substituent shift parameters have been derived from the chemical shift data. The relaxation times have been interpreted in terms of increasing segmental motion along the methylene chains of the carboxylic acid molecules which are associated at the carboxylic acid groups in the form of inverted micelles. Differences in the segmental motion between saturated and unsaturated carboxylic acids are rationalized on the grounds of intermolecular interactions between adjacent molecules in the inverted micelle structures.