Chirality-Dependent Copper-Diphenylalanine Assemblies with Tough Layered Structure and Enhanced Catalytic Performance

Chiral regulation to prepare functional materials has aroused considerable interest in recent years. However, little is known on the effect of chirality of ligands in the metal-organic coordination assembly process. We report the self-assembly of diphenylalanine peptide (Phe-Phe, FF), the core fragment of A beta protein, with metal copper ion (Cu2+) into metal-organic assemblies with chirality-encoded structures and properties. The chirality-dependent metal-dipeptide assembles with different morphologies and supramolecular chirality were obtained by facile changing of the FF chirality. Single-crystal results indicate that (L)-FF coordinated with Cu2+ into a cross-chain structure with a five-coordinated style, while the racemates of (L+D)-FF with Cu2+ crystallized into an (L)-Cu2+-(D)-Cu2+ alternated fourcoordinating structure, enabling a higher mechanical and catalytic performance. The Young's modulus of (L+D)-FF-Cu is as high as 34.36 GPa, which is 2.45 times higher than that of (L)-FF-Cu. Furthermore, both of them follow the characteristic enzyme kinetics and show higher catalytic activity than natural laccase at the same mass concentration. Specifically, the calculated catalytic efficiency (kcat/KM) of (L+D)-FF-Cu is 1.14 times higher than that of (L)-FF-Cu, and the (L+D)-FF-Cu shows significantly enhanced stability and reusability compared with (L)-FF-Cu. The results reveal that highly functional materials could be constructed by encoding the chirality of molecular building blocks.

Automated summary

Chiral regulation in the preparation of functional materials has been a topic of interest recently. However, there is limited understanding on the role of ligand chirality in metal-organic coordination assembly. In this study, we investigate the self-assembly of diphenylalanine peptide with copper ions to form metal-organic assemblies with chirality-encoded structures and properties. The different chirality of the peptide leads to the formation of metal-peptide assemblies with distinct morphologies and supramolecular chirality. These assemblies exhibit higher mechanical and catalytic performance compared to their individual components. The results highlight the potential of using chirality-encoded molecular building blocks for the fabrication of highly functional materials.