Search

The heterogenization of molecular catalysts within a porous solid acting as macroligand can advantageously open access to enhanced stability and productivity, and thus to more sustainable catalytic process. Herein, a porous organic polymer (POP) made through metal‐free polymerization using bipyridine repeating units is reported. This N‐rich POP is an efficient macroligand for the heterogenization of molecular rhodium complexes. The intrinsic catalytic activity of the heterogenized catalyst is slightly higher than that of its homogeneous molecular counterpart for formic acid production as a unique carbon‐containing product. The heterogenization of the rhodium catalysts enables recycling for a total productivity of up to 8.3 g of formic acid per gram of catalyst after 7 reuses using visible light as the sole energy source. [ABSTRACT FROM AUTHOR]

Oxidation of alkenes to carbonyls or diols compounds is important in synthesizing fine chemicals and pharmaceutical intermediates. We report the synthesis and characterization of an aluminum metal‐organic framework node‐supported copper(II) chloride (DUT‐5‐CuCl), which is an efficient heterogeneous catalyst for the oxidation of alkenes using H2O2 as an oxidizing agent. Styrene and various substituted styrenes were transformed into the corresponding carbonyl compounds in excellent selectivity and yields. DUT‐5‐CuCl is tolerant with various functional groups and could be recycled and reused at least 5 times in the oxidation of α‐methylstyrene. Unlike the oxidation of styrene derivatives, DUT‐5‐Cu catalyzed oxidation of aliphatic and cyclic alkenes produced 1,2‐diols compounds selectively. The mechanism of the DUT‐5‐Cu catalyzed oxidation of styrene to benzaldehyde was investigated in detail by various experiments such as the determination of reaction intermediates and characterization of the catalyst after catalysis, and computational studies. This work highlights the importance of MOF‐supported earth‐abundant metal catalysts for oxidation reactions to produce fine chemicals. [ABSTRACT FROM AUTHOR]

We report a metal‐organic framework (MOF) supported monoligated phosphine‐cobalt complex, which is an active heterogeneous catalyst for aromatic C−H borylation and alkene hydroboration. The mono(phosphine)‐Co catalyst (MOF−P−Co) was prepared by metalation of a porous triarylphosphine‐functionalized MOF (MOF−P) with CoCl2 followed by activation with NaEt3BH. The MOF catalyst has a broad substrate scope with excellent functional group tolerance to afford arene‐ and alkyl‐boronate esters in excellent yields and selectivity. MOF−P−Co gave a turnover number (TON) of 30,000 and could be recycled and reused at least 13 times in arene C−H borylation. Importantly, the attempt to prepare the homogeneous control (Ph3P−Co) using triphenylphosphine was unsuccessful due to the facile disproportionation reactions or intermolecular ligand exchanges in the solution. In contrast, the site isolation of the active mono(phosphine)‐Co species within the MOF affords the robust and coordinatively unsaturated metal complexes, allowing to explore their catalytic properties and the reaction mechanism. [ABSTRACT FROM AUTHOR]

In the present study, a new photoactive bimetallic Cu‐Au@g‐C3N4 catalytic system was designed by impregnating Cu and Au NPs over the graphitic carbon nitrite (g‐C3N4) surface. Characterization of the catalyst using multiple techniques illustrated that very small‐sized Cu and Au NPs were monodispersed on the g‐C3N4 surface, which were obtained by the in situ reduction of the metal salts using sodium borohydride. The as‐synthesized bimetallic Cu‐Au@g‐C3N4 catalyst efficiently catalyzed the hydroxylation of benzene (HOB) via C–H activation under visible light irradiation at room temperature. The dominant role of the synergistic interaction between Cu and Au NPs were further elucidated by high resolution transmission electron microscopy (HR‐TEM) studies and X‐ray photoelectron spectroscopy (XPS) analysis. This study may provide a new avenue for the preparation of photoactive bimetallic catalysts and offers insight into the synergistic interaction of bimetallic catalytic HOB reactions. [ABSTRACT FROM AUTHOR]