Recent advances in organic chemistry and materials chemistry have enabled the porosity of new materials to be accurately controlled on the nanometer scale. In this context, metal–organic frameworks (MOFs) have rapidly become one of the most attractive classes of solid supports currently under investigation in heterogeneous catalysis. Their unprecedented degree of tunability gives MOFs the chance to succeed where others have failed. The past decade has witnessed an exponential growth in the complexity of new structures. MOFs with a variety of topologies and pore sizes show excellent stability across wide ranges of pH and temperature. Even the controlled insertion of defects, to alter the MOF’s properties in a predictable manner, has become commonplace. However, research on catalysis with MOFs has been sluggish in catching up with modern trends in organic chemistry. Relevant issues such as enantioselective processes, C–H activation, or olefin metathesis are still rarely discussed. In this Perspective, we highlight meritorious examples that tackle important issues from contemporary organic synthesis, and that provide a fair comparison with existing catalysts. Some of these MOF catalysts already outcompete state-of-the-art homogeneous solutions. For others, improvements may still be required, but they have merit in aiming for the bigger challenge. Furthermore, we also identify some important areas where MOFs are likely to make a difference, by addressing currently unmet needs in catalysis instead of trying to outcompete homogeneous catalysts in areas where they excel. Finally, we strongly advocate for rational design of MOF catalysts, founded on a deep mechanistic understanding of the events taking place inside the pore.

The conjugated frustrated phosphane/borane Lewis pairs formed by 1,1-carboboration of a substituted diphenylphosphino acetylene, undergo a synergistic 1,1-addition reaction to n-butyl isocyanide with formation of new B-C and P-C bonds to the former isonitrile carbon atom. Using tert-butyl isocyanide dynamic behaviour between the isocyanide-[B] adduct and the 1,1-addition product formation was observed in solution. The different modes of isocyanide binding to the FLPs in the solid state were characterized using X-ray crystal structure analyses and comprehensive 11 B and 31 P solid-state magicangle-spinning (MAS-) NMR experiments. The free FLP, the Lewis adduct at the borane group, and the cyclic product resulting from isocyanide addition to both reaction centers, can be differentiated via 11 B and 31 P isotropic chemical shifts, 11 B nuclear electric quadrupole coupling constants, isotropic indirect 11 B-31 P spin-spin coupling constants, and 11 B/ 31 P internuclear distances measured by rotational echo double resonance.

The mechanism of the N-alkylation of amines with alcohols catalyzed by an iridium complex containing an Nheterocyclic carbene (NHC) ligand with a tethered alcohol/alkoxide functionality was investigated by a combination of experimental and computational methods. The catalyst resting state is an iridium−hydride species containing the amine substrate as a ligand, and decoordination of the amine, followed by coordination of the imine intermediate to the iridium center, constitute the rate-determining step (rds) of the catalytic process. The alcohol/alkoxide that is tethered to the NHC participates in every step of the catalytic cycle by accepting or releasing protons and forming hydrogen bonds with the reacting species. Thus, the iridium complex with the alcohol/alkoxide tethered to the N-heterocyclic carbene ligand acts as a bifunctional catalyst.

A molecular H2-evolving catalyst, [Fe2(cbdt)(CO)6] ([FeFe], cbdt = 3-carboxybenzene-1,2-dithiolate), has been attached covalently to an amino-functionalized MIL-101(Cr) through an amide bond. Chemical reduction experiments reveal that the MOF channels can be clogged by ion pairs that are formed between the oxidized reductant and the reduced catalyst. This effect is lessened in MIL-101-NH-[FeFe] with lower [FeFe] loadings. On longer timescales, it is shown that large proportions of the [FeFe] catalysts within the MOF engage in photochemical hydrogen production and the amount of produced hydrogen is proportional to the catalyst loading.

al. (2015) Effect of the functionalisation route on a Zr-MOF with an Ir-NHC complex for catalysis.Chemical Communications, 51(54):

Bifunctional complexes bearing N-heterocyclic carbene (NHC) ligands functionalized with hydroxy or amine groups were synthesized to measure the beneficial effect of different modes of metal–ligand cooperation in the acceptorless dehydrogenation of alcohols. In comparison to complexes with an amine moiety, hydroxy-functionalized iridium catalysts showed superior activity. In contrast to alcohols, 1,4-diols underwent cyclization to give the corresponding tetrahydrofurans without involving dehydrogenation processes. Mechanistic investigations to rationalize the “OH effect” in these types of complexes have been undertaken.

Chemoselectivereduction of the C=Cbond in avariety of a,b-unsaturatedc arbonylc ompounds using supported palladium nanoparticles is reported.T hree differenth eterogeneous catalysts were compared using 1a tm of H 2 : 1) nano-Pd on am etal-organic framework (MOF:P d 0 -MIL-101-NH 2 (Cr)), 2) nano-Pd on as iliceous mesocellularf oam (MCF:P d 0 -AmP-MCF), and 3) commerciallya vailablep alladium on carbon( Pd/C). Initials tudies showed that the Pd@MOF and Pd@MCF nanocatalysts were superior in activity and selectivity compared to commercial Pd/C. Both Pd 0 -MIL-101-NH 2 (Cr) and Pd 0 -AmP-MCF werec apable of delivering the desired products in very short reaction times (10-90 min) with low loadings of Pd (0.5-1 mol %). Additionally, the two catalytic systems exhibited high recyclability and very low levels of metal leaching.

Nanocarbons, such as fullerenes, carbon nanotubes, and graphenes, have long inspired the scientific community. In order to synthesize nanocarbon molecules in an atomically precise fashion, many synthetic reactions have been...