The Förster radius for energy transfer from naphthalene to anthracene in polyesters with oxyethylene spacers

Abstract

AbstractModel compounds for a series of polyesters in which 3,6,9, and 12‐rotatable CH2O and CH2CH2 bonds separate rigid units have been studied using the efficiency of nonradiative singlet energy transfer from naphthalene to anthracene. The model compounds have the structure naph‐CO(OCH2CH2)mOOC‐anth with m of 1–4, where naph and anth denote 2‐naphthyl and 9‐anthranyl groups, respectively. This series of compounds covers a larger range of potential separation of the two chromophores than was possible in an earlier study, in which the flexible spacers consisted of 2–6 methylene units. The nonradiative singlet energy transfer has an efficiency that depends on the solvent viscosity and on m. The theoretical analysis employs a rotational isomeric state model for the conformations of these molecules. The Förster radius for transfer from naphthalene to anthracene in this system is 16 ± 2 Å, and is nearly independent of whether the spacers are constructed from oxyethylene or methylene units.