Regulating the Piezoelectricity of Cyclic Dipeptide-Based Supramolecular Materials through Co-Assembly Strategy

Supramolecular co-assembly can modulate the architecture of molecular assemblies, thereby influencing their electromechanical properties. However, the relationship between supramolecular packing and electromechanical response of co-assemblies remains largely unexplored, posing a challenge in designing high-performance bioinspired piezoelectric materials. Herein, we combined experiments and theoretical calculations to systematically explore the regulation of supramolecular packing and electromechanical properties of cyclic l-aspartyl-l-aspartyl (cyclo-DD (LL))-based assemblies through co-assembling with pyridine derivatives. Crystal structures indicated that intermolecular hydrogen bonding between the carboxyl group of the cyclic dipeptide and the pyridine ring resulted in a markedly different molecular organizations and packing modes of co-assemblies. Density functional theory calculations revealed that increasing the molecular length of the pyridine derivatives enhanced the polarization effect and piezoelectric response of the cyclo-DD (LL)-based co-assemblies due to the reduced structural symmetry. Notably, the maximum piezoelectric coefficient of the cyclo-DD (LL)/4,4'-trimethylenedipyridine (TDP) co-assembly was predicted to be 140.8 pC/N, representing the highest value among peptide-based co-assemblies. Furthermore, cyclo-DD (LL)/TDP co-assembly based piezoelectric nanogenerator could generate stable open-circuit voltages over 3 V under an applied mechanical force of 50 N. For the first time, peptide-based co-assemblies were utilized as active piezoelectric materials to successfully power a display screen. Moreover, the effect of chirality on the piezoelectricity of cyclic dipeptide-based co-assemblies was investigated. This work presents an effective co-assembly strategy to manipulate the piezoelectric response of bioinspired cyclic dipeptide-based assemblies, advancing the development of high-performance piezoelectric molecular materials for sustainable energy harvesting systems.