Enhanced Stability in Rigid Peptide‐Based Porous Materials

Abstract

Pepped up: Notwithstanding the intrinsic conformational flexibility of peptides, [Zn(Gly-Thr)(2)] behaves as a robust porous metal-organic framework thanks to the rigidity introduced by the use of Gly-Thr (see scheme). This rigidity arises from the sequence of amino acids in the dipeptide that locks its conformational flexibility in the framework.

Biologically derived metal organic frameworks

“…[105] Deformation of the host framework, and the low energy states that are accessed, are characterized by cooperative torsions that are thermally accessible in the arrangement of the ligands in [Zn(GlyAla)2] by interactions of the coordinated metal center, and the hydrogen bonding in the rigidly planar amide unit hanging the ligand from GlyAla to GlyThr affords [Zn(GlyThr)2]•MeOH, an also 2-dimensional bio-MOF which displays 1-dimensional pores. [168] Here, Zn II has a distorted octahedral geometry and each Zn II metal center is coordinated six-fold by four dipeptide molecules. [168] Two peptides interact through the monodentate C-terminus of the Thr carboxylate group, and two other forming a five-membered N,Ochelate with the amine and oxo groups of the N-terminus Gly residue.…”

“…[168] Here, Zn II has a distorted octahedral geometry and each Zn II metal center is coordinated six-fold by four dipeptide molecules. [168] Two peptides interact through the monodentate C-terminus of the Thr carboxylate group, and two other forming a five-membered N,Ochelate with the amine and oxo groups of the N-terminus Gly residue. [168] Each GlyThr acts as a µ2-ligand, connecting two metal ions thereby forming 2-dimensional grid-like layers along the b-axis, whereas the 1-dimensional channels are packed along the a-axis, occupied by methanol guest molecules.…”

“…[168] Two peptides interact through the monodentate C-terminus of the Thr carboxylate group, and two other forming a five-membered N,Ochelate with the amine and oxo groups of the N-terminus Gly residue. [168] Each GlyThr acts as a µ2-ligand, connecting two metal ions thereby forming 2-dimensional grid-like layers along the b-axis, whereas the 1-dimensional channels are packed along the a-axis, occupied by methanol guest molecules. [168] [107] [Zn(GlyThr)2]behaves as a "classically" rigid microporous framework due to the rigidity of the GlyThr ligand which is due to its conformation via intralayer hydrogen bonding, as well as the structure remaining unchanged upon activation.…”

“…[168] Each GlyThr acts as a µ2-ligand, connecting two metal ions thereby forming 2-dimensional grid-like layers along the b-axis, whereas the 1-dimensional channels are packed along the a-axis, occupied by methanol guest molecules. [168] [107] [Zn(GlyThr)2]behaves as a "classically" rigid microporous framework due to the rigidity of the GlyThr ligand which is due to its conformation via intralayer hydrogen bonding, as well as the structure remaining unchanged upon activation. [168] Reinforcement of structural stability can be attributed to the -OH groups found in the side chains of the Thr amino acid, which enable inter-and intra-layer hydrogen bonding, overall favoring chelation between the metal ion and the peptide.…”

“…[168] [107] [Zn(GlyThr)2]behaves as a "classically" rigid microporous framework due to the rigidity of the GlyThr ligand which is due to its conformation via intralayer hydrogen bonding, as well as the structure remaining unchanged upon activation. [168] Reinforcement of structural stability can be attributed to the -OH groups found in the side chains of the Thr amino acid, which enable inter-and intra-layer hydrogen bonding, overall favoring chelation between the metal ion and the peptide. [168] This reinforcement and interaction is specific to the Thr in the framework, and operates between adjacent layers providing the strengthened structural stability in three-dimensions, resulting in higher cooperativity.…”