Assembly and Covalent Cross-Linking of an Amine-Functionalised Metal-Organic Cage

• Main Authors: Matthew L. Schneider, Adrian W. Markwell-Heys, Oliver M. Linder-Patton, Witold M. Bloch
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2021-05-01
• Series: Frontiers in Chemistry
• Subjects: cage compound; self-assembly; coordination; cross-linking; amine-functionality; porosity
• Online Access: https://www.frontiersin.org/articles/10.3389/fchem.2021.696081/full

The incorporation of reactive functional groups onto the exterior of metal-organic cages (MOCs) opens up new opportunities to link their well-defined scaffolds into functional porous solids. Amine moieties offer access to a rich catalogue of covalent chemistry; however, they also tend to coordinate undesirably and interfere with MOC formation, particular in the case of Cu2 paddlewheel-based MOCs. We demonstrate that tuning the basicity of an aniline-functionalized ligand enables the self-assembly of a soluble, amine-functionalized Cu4L4 lantern cage (1). Importantly, we show control over the coordinative propensity of the exterior amine of the ligand, which enables us to isolate a crystalline, two-dimensional metal-organic framework composed entirely of MOC units (2). Furthermore, we show that the nucleophilicity of the exterior amine of 1 can be accessed in solution to generate a cross-linked cage polymer (3) via imine condensation.