Pseudo‐heterolepticity in Low‐Symmetry Metal‐Organic Cages

Abstract

Heteroleptic metal-organic cages, formed through integrative self-assembly of ligand mixtures, are highly attractive as reduced symmetry supramolecular hosts. Ensuring high-fidelity, non-statistical self-assembly, however, presents a significant challenge in molecular engineering due to the inherent difficulty in predicting thermodynamic energy landscapes. In this work, two conceptual strategies are described that circumvent this issue, using ligand design strategies to access structurally sophisticated metal-organic hosts. Using these approaches, it was possible to realise cavity environments described by two inequivalent, unsymmetrical ligand frameworks, representing a significant step forward in the construction of highly anisotropic confined spaces.

Selective Supramolecular Recognition of Nitroaromatics by a Fluorescent Metal–Organic Cage Based on a Pyridine-Decorated Dibenzodiaza-Crown Macrocyclic Co(II) Complex

“…As a recently reported example, a prism-type hexacationic cage 3 6+ bears three arms that are capable of forming 12 potential hydrogen bonds with Cl – ···Cl – and/or Cl – ···Br – concurrently inside the cavity of the cage . There are also reports on size-selective capture of anions owing to the shape and size fitness of the anion (guest) and the cage interior. ,, Moreover, the presence of more than one cavity within the cage can result in simultaneous multiple capturing of anions, separated by isolated cavities. − Table S1 summarizes some of the reported host MOCs for encapsulating more than one anion in their cavity. ,− Meanwhile, the photophysical properties of ligand frameworks and metal nodes within the cage lead to applications of the MOCs in molecular sensing and recognition, , gas separation and storage, , catalysis, − drug delivery, , and molecular separation. , …”