Conducting polymers are routinely used in optoelectronic biomaterials, but large polymer polydispersity and 11 poor aqueous compatibility complicate integration with biomolecular templates and development of discrete and defined 12 supramolecular complexes. Herein, we report on a chiro-optical hybrid material generated by the self-assembly of an anionic 13 peptide and a chemically defined cationic pentameric thiophene in aqueous environment. The peptide acts as a stereochemical 14 template for the thiophene and adopts an α-helical conformation upon association, inducing optical activity in the thiophene 15 π−π* transition region. Theoretical calculations confirm the experimentally observed induced structural changes and indicate 16 the importance of electrostatic interactions in the complex. The association process is also probed at the substrate−solvent 17 interface using a peptide-functionalized gold nanoparticle, indicating that the peptide can also act as a scaffold when 18 immobilized, resulting in structurally well-defined supramolecular complexes. The hybrid complex could rapidly be assembled, 19 and the kinetics of the formation could be monitored by utilizing the local surface plasmon resonance originating from the gold 20 nanoparticles. We foresee that these findings will aid in designing novel hybrid materials and provide a possible route for the 21 development of functional optoelectronic interfaces for both biomaterials and energy harvesting applications.

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