Variations in the heterogeneity of the decay of the fluorescence in six procyanidin dimers

Abstract

The decay of the fluorescence has been measured in 1,4-dioxane for six dimers of (2R,3R)-(-)-epicatechin and (2R,3S)-(+)-catechin, hereafter denoted simply epicatechin and catechin. The dimers are epicatechin-(4β→8)-catechin, epicatechin-(4β→8)-epicatechin, catechin-( 4α→8)-catechin, catechin-(4α→8)-epicatechin, epicatechin-(4β→6)-epicatechin, and epicatechin-(4β→8;2β→O→7)-epicatechin. The monomers and the bridged dimer have a fluorescence that decays as a single exponential. The remaining five dimers have a heterogeneous decay that can be described by the sum of two exponentials. The heterogeneity is most apparent in the two dimers with 4α→8 interflavan bonds. In view of the molecular origin of the heterogeneous decay in the presence of two rotational isomers at the interflavan bond, polymeric procyanidins with predominantly α stereochemistry for the interflavan bond at C(4) should be more disordered and more compact than those with predominantly β stereochemistry.

Citation

Cho, Donghwan; Tian, Rujiang; Porter, Lawrence J.; Hemingway, Richard W.; Mattice, Wayne L. 1990. Variations in the heterogeneity of the decay of the fluorescence in six procyanidin dimers. Journal of the American Chemical Society 112(11):4273-4277