Utilizing pi-peptide supramolecular polymers to template growth of hybrid organic–inorganic electronic materials†

We investigated and compared the growth of three different minerals (KCl, CsCl, and CdS) templated by assemblies of perylene diimide (PDI)-based π-peptides with varying amino acid sequences. KCl and CsCl were chosen since they are single cation-anion minerals with very different cationic radii. Further, KCl is an insulator while CsCl has low ionic conductivity. CdS is a more optoelectronically active material that serves as a prototype for minerals that could form electronically conductive or potentially photoconductive pathways. KCl and CsCl morphologies were dependent on the templating peptide, with varying degrees of density and branching of mineral deposits and polymorphism shown in X-ray diffractograms. The mineralization also affected peptide absorbance spectra, indicating different aggregate electronic arrangements. While KCl under conditions used here formed thick, electrically insulating deposits, CsCl deposits showed peptide-dependent ionic conductivity. CdS templated by one of the π-peptide materials showed less definitive templating, but morphology that was more directional than the non-templated case. Substantial electronic conductivity was measured for this latter case. These results indicate the potential to utilize π-peptide templated growth of minerals to form controllable hybrid organic/inorganic structures for multiple electrical applications.