Synthesis of Polycarboxylate Rhodium(II) Metal–Organic Polyhedra (MOPs) and their use as Building Blocks for Highly Connected Metal–Organic Frameworks (MOFs)

Abstract

Use of preformed metal‐organic polyhedra (MOPs) as supermolecular building blocks (SBBs) for the synthesis of metal‐organic frameworks (MOFs) remains underexplored due to lack of robust functionalized MOPs. Herein we report the use of polycarboxylate cuboctahedral RhII‐MOPs for constructing highly‐connected MOFs. Cuboctahedral MOPs were functionalized with carboxylic acid groups on their 12 vertices or 24 edges through coordinative or covalent post‐synthetic routes, respectively. We then used each isolated polycarboxylate RhII‐MOP as 12‐c cuboctahedral or 24‐c rhombicuboctahedral SBBs that, upon linkage with metallic secondary building units (SBUs), afford bimetallic highly‐connected MOFs. The assembly of a pre‐synthesized 12‐c SBB with a 4‐c paddle‐wheel SBU, and a 24‐c SBB with a 3‐c triangular CuII SBU gave rise to bimetallic MOFs having ftw (4,12)‐c or rht (3,24)‐c topologies, respectively.

Strategies for the Construction of Functional Materials Utilizing Presynthesized Metal‐Organic Cages (MOCs)

“…Recently, Carné-Sánchez, Maspoch and co-workers synthesized two MOCs with polycarboxylate groups on the periphery by using coordinative or covalent postsynthetic routes, respectively. [42] Among them, MOC with 12 carboxyl groups on the periphery can be obtained by the reaction of MOC-15 with 4-pyridinecarboxylic acid, and it can be considered as 12-c cuboctahedral supramolecular building blocks (SBBs) to form MOF with ftw (4,12)-c topology (Figure 3, compound 7) when connected by paddle-wheel Cu(II) secondary building units (SBUs). While MOC-16 that has 24 carboxyl groups on the periphery can be seen as 24-c SBB to generate MOFs having rht (3,24)-c topology via the linkage of triangular Cu(II) SBU (Figure 3, compound 8).…”

Giant oligomeric porous cage-based molecules

“…37 Consequently, the high connectivity of Rh-MOPs complicates the control of their polymerisation into well-dened oligomeric structures rather than extended networks. [38][39][40][41] To address this challenge, we aimed to create Rh-MOPs with only one reactive site on their surface. By employing protecting groups, we selectively masked the reactivity of 23 of the 24 reactive sites to yield 1connected (1-c) Rh-MOPs.…”