Spiroligomer-based macrocycles for atomically precise membranes
Abstract
"Here, we report a new class of peptidomimetic macrocycles with well-defined three-dimensional structures and low conformational flexibility. They are assembled from fused-ring spiro-ladder oligomers (spiroligomers) by modular solid-phase synthesis. Two-dimensional nuclear magnetic resonance confirms their shape persistency. Triangular macrocycles of tunable sizes assemble into membranes with atomically precise pores, which exhibit size and shape-dependent molecular sieving towards a series of structurally similar compounds."
Rigid Geometry & Pore Consistency
Conventional polymeric membranes rely on random network formation, leading to broad pore size distributions. In this work, we demonstrate the assembly of triangular macrocycles (12 and 13) that maintain a rigid inner cavity due to the ladder-like structure of the spiroligomer backbone.
By crosslinking these macrocycles into thin films on a PES support, we achieved membranes with "atomically precise" pores. Unlike flexible peptides that might collapse or change shape, these macrocycles are shape-persistent, confirmed by extensive 2D NMR studies (ROESY correlations).
Molecular Sieving Performance
The membranes demonstrated exceptional selectivity. They could effectively differentiate between molecules not just by molecular weight, but by 3D geometry. For instance, the membrane successfully rejected linear spiroligomers while allowing smaller or more flexible molecules to pass, effectively acting as a molecular sieve.
