Anisotropy of the fluorescence from the monomer, five oligomers, and a polymer of epicatechin

The steady‐state fluorescence anisotropy r has been measured at 25°C for dilute solutions of epicatechin units connected by interflavan bonds with 4β → 8 stereochemistry. The molecules studied are monodisperse oligomers from the monomer through the hexamer, and a polydisperse sample with a number‐average degree of polymerization x n of 10. The hexamer and smaller oligomers have been removed from the polydisperse sample. All samples have a very small value of r in 1,4‐dioxane and in methanol. Higher values of r are seen in ethylene glycol and in glycerol. In the latter two solvents, the monomer has significantly higher r than any species with x n > 1. This observation is interpreted as evidence for the presence of excitation migration from one monomer to another in the dimer and species of higher x n .