Noncovalent Immobilization of Cationic Ruthenium Complex in a Metal–Organic Framework by Ion Exchange Leading to a Heterogeneous Olefin Metathesis Catalyst for Use in Green Solvents

Abstract

A simple strategy for noncovalent immobilization of an olefin metathesis catalyst inside a (Cr)­MIL-101-SO3Na metal–organic framework (MOF) was presented. The olefin metathesis active corean alkylidene complex bearing an ammonium-tagged NHC ligand (Apeiron’s FixCat)was immobilized by ion exchange facilitated by the use of crown ether. The hybrid material thus obtained was shown with a number of model substrates to exhibit high activity and selectivity in a wide range of solvents. Next, selected polyfunctional pharmaceutically related substrates were transformed using 0.8–0.5 mol % of the Ru@MOF in polar solvents such as acetone and dimethyl carbonate, making this technology interesting in the context of green solvent utilization.

Advanced sol–gel process for efficient heterogeneous ring-closing metathesis

“…1 , A-C catalysts. We expected the quaternary ammonium group in the type 2 catalysts to strongly (but not covalently) bind to the silica surface by adsorption, probably via electrostatic bonds with the silanol groups and/or the oxides on the surface of the sol–gel matrix 34 , 35 , 37 , 67 . This bond should decrease catalyst leakage, even during a metathesis reaction conducted in a polar solvent.…”

“…When type 2 catalysts were entrapped in sol–gel matrices, the leakage of the catalyst from the matrix was significantly improved, and higher conversion rates were obtained, compared to these of type 1 catalysts in table S1 . The leakage improvement could be due to binding of the quaternary ammonium group, in the type 2 catalysts, to the silica surface by adsorption, probably via electrostatic bonds with the silanol groups and/or the oxides on the surface of the sol–gel matrix 34 , 35 , 37 , 67 . Another indication that catalysts A-C bind to the matrix—i.e., become entrapped within it, thus limiting their leakage – can be found in the surface area results.…”

Ruthenium Olefin Metathesis Catalysts Featuring N-Heterocyclic Carbene Ligands Tagged with Isonicotinic and 4-(Dimethylamino)benzoic Acid Rests: Evaluation of a Modular Synthetic Strategy

“…Moreover, most of the covalently linked catalysts reported show diminished activity, and their reusability remains moderate. Non-covalent binding can rely on electrostatic interactions [23][24][25][26][27], reversible π-π interactions [28,29], or physio-sorption on porous materials, such as silica [30][31][32][33][34][35], charcoal, cellulose, wool, and filter paper [36], dendrimers [37][38][39], SBA-15 [40], or MOF [41][42][43].…”

In Situ Growth of ZIF-8 Nanocrystals on the Pore Walls of 3D Ordered Macroporous TiO2 for a One-Pot Cascade Reaction

“…Moreover, in some reaction systems, the protection-deprotection process and purification process of the intermediate are omitted [16,17]. MOFs consist of compounds based on metal ions or clusters coordinated to organic ligands to form one-, two-, or three-dimensional structures that generate sites to anchor the catalysts [18][19][20]. Allowing metal nanoparticles to embed in MOF, achieving a catalytic cascade reaction, is a common strategy.…”