Manipulating Association of Electroactive Chromophores via the Use of Peptidic Templates

The performance of organic or polymeric devices such as light-emitting diodes, thin-film transistors, and photovoltaic devices depends on the alignment and spacing between electroactive chains, but achieving such control on angstrom length scales has proven a significant challenge. It is well-known that Nature executes such accurate regulation at a molecular level in proteins and that polypeptidic scaffolds can be used to organize functional groups. We have therefore employed peptidic scaffolds to align multiple electroactive molecules in desired orientations and spacing to manipulate the electronic behavior of side chains. The controlled electronic behavior of the hybrid molecules with small changes in architecture was indicated via photoluminescence, photoluminescence excitation, and 1H NMR spectroscopy. Methylstilbene molecules form a ground-state complex and excimer when placed approximately 6 Å apart on the same side of a peptide chain, but act independently when placed on opposite sides of the chain or at longer distances. These results prove that peptidic scaffolds can be used to control interactions and photophysics in electroactive organics, at distances relevant for electroactive devices.