Conformations and interactions of excited stales. I. Model compounds for polymers

From observations on model compounds having two or more benzene rings and structures analogous to high polymers of interest (polystyrene and aromatic polypeptides), we conclude that interactions of pairs of benzene rings sufficiently strong to cause observable excimer emission requires that these rings be separated by no more than 2–3 A. and that they be in an approximately parallel‐stacked, face‐to‐face arrangement. If a molecule does not have such a configuration of its aromatic rings in its ground‐state conformation, strong excimer emission can still occur provided there is a conformation with the appropriate ring configuration which can be attained within the radiative lifetime of the excited state.