Assembly of π‑Stacking Helical Peptides into a Porous and Multivariable Proteomimetic Framework

The evolution of proteins from simpler,
self-assembled peptides
provides a powerful blueprint for the design of complex synthetic
materials. Previously, peptide–metal frameworks using short
sequences (≤3 residues) have shown great promise as proteomimetic
materials that exhibit sophisticated capabilities. However, their
development has been hindered due to few variable residues and restricted
choice of side-chains that are compatible with metal ions. Herein,
we developed a noncovalent strategy featuring π-stacking bipyridyl
residues to assemble much longer peptides into crystalline frameworks
that tolerate even previously incompatible acidic and basic functionalities
and allow an unprecedented level of pore variations. Single-crystal
X-ray structures are provided for all variants to guide and validate
rational design. These materials exhibit hallmark proteomimetic behaviors
such as guest-selective induced fit and assembly of multimetallic
units. Significantly, we demonstrate facile optimization of the framework
design to substantially increase affinity toward a complex organic
molecule.