Rational Design of a Porous Supramolecular Peptide Framework (SPF): A Crystalline Tetraproline in the Polyproline II Conformation

Herein, we present the first high resolution single crystal structure of an unfunctionalized tetrameric proline in the poly-proline II conformation. This rationally designed oligoproline tetramer, self-assembles to form a permanently porous crys-talline supramolecular peptide framework (SPF). Thermal activation, guest inclusion and thermally induced release of chemical guests have been demonstrated for this novel system. This discovery provides a conclusive insight into the pre-viously ambiguous conformation of short oligoprolines and will allow for the further development of proline-based pep-tide linkers in the rational design of SPFs and metal-peptide frameworks.