Transmetalation: routes to metal exchange within metal–organic frameworks

Abstract

The present work is a critical review of metal exchange (transmetalation) involving metal nodes and metalated struts in metal-organic frameworks. Particular emphasis is given to drawing parallels between different examples of transmetalation in order to understand the influence of coordination environment, solvents, nature of the metals and other variables on the process. We hope that the present review will be of use to those involved in the incorporation of various metal centers to create isostructural MOFs and study their properties.

Porous Coordination Polymers of Diverse Topologies Based on a Twisted Tetrapyridylbiaryl: Application as Nucleophilic Catalysts for Acetylation of Phenols

“…[9] In recent years, postsynthetic modification of MOFs has been demonstrated as a very effective protocol to introduce functionality, which is not achieved by de novo approaches involving organic linker design and metal ion choice.…”

Design and Construction of Chemically Stable Metal-Organic Frameworks

“…Much work has been done on elucidating the factors that could facilitate metal exchange. 39 It has been pointed out that several factors, such as ionic radii, concentration of the exchange solution, reaction kinetics, solvent effects, coordination geometries of the metal ions, pore size, and the flexibility of the framework can all affect the proceeding of metal exchange. Readers who are interested in this part are recommended to read an excellent review paper published by Lalonde et al in 2013.…”

“…39 Most successful metal exchange operations are conducted on frameworks built with divalent metal ions, because the coordination bonds formed by these ions and carboxylate groups are not very strong and thus significantly facilitate metal exchange. 39 To enhance the stability of the framework, divalent metal ions are substituted with high valent metal ions, which could form stronger coordination bonds with carboxylate groups. However, attempts to replace divalent metal ions directly with high valent metal ions are rarely successful.…”

Research Update: A hafnium-based metal-organic framework as a catalyst for regioselective ring-opening of epoxides with a mild hydride source

“…New catalytic MOFs can be synthesized: (a) de novo, (b) via post-synthetic modification of existing MOFs, or (c) solvent-assisted linker exchange, or other building-block-replacement chemistry. [11][12][13][14][15] There are two general approaches to engendering catalytic responses from MOFs: one is to incorporate a catalytic site into the linkers of the MOF, 11,16,17 while the other is to take advantage of open (or labile) metal-ion-coordination sites present at inorganic nodes-either by design or as a consequence of MOF structural defects such as missing linkers. 18,19 Recently, we reported a Hf 6 based analogue of NU-1000, 20 Hf-NU-1000.…”