Carbodiimide-fueled assembly of π-conjugated peptides regulated by electrostatic interactions

Peptides naturally have stimuli-adaptive structural conformations that are advantageous for endowing synthetic materials with dynamic functionalities. Here, we investigate a carbodiimide-based approach, combined with electrostatic modulation, to instruct π-conjugated peptides to self-assemble and be responsive to thermal disassembly cues upon consumption of the assembly trigger. Quaterthiophene-functionalized peptides are utilized as a model system herein to study the formation of kinetically trapped structures at non-equilibrium states. Peptides were designed to have aspartic acid at the termini to allow intramolecular anhydride formation upon adding carbodiimide, which consequentially reduces the electrostatic repulsion and facilitates assembly. We show that the carbodiimide-fueled assembly and subsequent thermally assisted disassembly can be modulated by the net charge of the peptidic monomers, suggesting an assembly mechanism that can be encoded by sequence design. This carbodiimide-based approach for the assembly of designer π-conjugated systems offers a unique opportunity to develop bioelectronic supramolecular materials with controllable formation of transient structures.