Zhifeng Dai

Highly Efficient Heterogeneous Hydroformylation over Rh-Metalated Porous Organic Polymers: Synergistic Effect of High Ligand Concentration and Flexible Framework

A series of diphosphine ligand constructed porous polymers with stable and flexible frameworks have been successfully synthesized under the solvothermal conditions from polymerizing the corresponding vinyl-functionalized diphosphine monomers. These insoluble porous polymers can be swollen by a wide range of organic solvents, showing similar behavior to those of soluble analogues. Rather than just as immobilizing homogeneous catalysts, these porous polymers supported with Rh species demonstrate even better catalytic performance in the hydroformylations than the analogue homogeneous catalysts. The sample extraordinary performance could be attributed to the combination of high ligand concentration and flexible framework of the porous polymers. Meanwhile, they can be easily separated and recycled from the reaction systems without losing any activity and selectivity. This excellent catalytic performance and easy recycling heterogeneous catalyst property make them be very attractive. These diphosphine ligand constructed porous polymers may provide new platforms for the hydroformylation of olefins in the future.

Imparting amphiphobicity on single-crystalline porous materials

The sophisticated control of surface wettability for target-specific applications has attracted widespread interest for use in a plethora of applications. Despite the recent advances in modification of non-porous materials, surface wettability control of porous materials, particularly single crystalline, remains undeveloped. Here we contribute a general method to impart amphiphobicity on single-crystalline porous materials as demonstrated by chemically coating the exterior of metal-organic framework (MOF) crystals with an amphiphobic surface. As amphiphobic porous materials, the resultant MOF crystals exhibit both superhydrophobicity and oleophobicity in addition to retaining high crystallinity and intact porosity. The chemical shielding effect resulting from the amphiphobicity of the MOFs is illustrated by their performances in water/organic vapour adsorption, as well as long-term ultrastability under highly humidified CO2 environments and exceptional chemical stability in acid/base aqueous solutions. Our work thereby pioneers a perspective to protect crystalline porous materials under various chemical environments for numerous applications.

A hierarchical porous ionic organic polymer as a new platform for heterogeneous phase transfer catalysis

In this work we demonstrate for the first time the construction of a hierarchical porous ionic organic polymer via the polymerization of the vinyl-functionalized quaternary phosphonium salt monomer under solvothermal conditions. The resultant polymerized quaternary phosphonium (PQP) salt features a hierarchical porous structure and excellent amphiphilicity. After anion-exchange with peroxotungstate, the afforded W2O11/PQP demonstrates excellent performances as a heterogeneous phase-transfer catalyst in the context of epoxidation of olefin and oxidation of dibenzothiophene when using the environmentally benign H2O2 as the oxidant, superior to the homogeneous counterparts and other types of phase-transfer catalysts. Our work thereby paves a way to advance hierarchical porous ionic organic polymers as a new type of platform for heterogeneous phase transfer catalysis.

A Hierarchical Bipyridine‐Constructed Framework for Highly Efficient Carbon Dioxide Capture and Catalytic Conversion

As a C1 feedstock, CO2 has the potential to be uniquely highly economical in both a chemical and a financial sense. Porous materials bearing particular binding and active sites that can capture and convert CO2 simultaneously are promising candidates for CO2 utilization. In this work, a bipyridine-constructed polymer featuring a high surface area, a hierarchical porous structure, and excellent stability was synthesized through free-radical polymerization. After metalation, the resultant catalysts exhibited superior activities in comparison with those of their homogeneous counterparts in the cycloaddition of CO2 to epoxides. The high performance of the heterogeneous catalysts originates from cooperative effects between the CO2 -philic polymer and the embedded metal species. In addition, the catalysts showed excellent stabilities and are readily recyclable; thus, they are promising for practical utilization for the conversion of CO2 into value-added chemicals.

Zirconium Oxide Supported Palladium Nanoparticles as a Highly Efficient Catalyst in the Hydrogenation–Amination of Levulinic Acid to Pyrrolidones

The selective hydrogenation–amination of levulinic acid into pyrrolidones is regarded as one of the most important reactions to transform biomass‐derived lignocellulose feedstocks into valuable chemicals. Here we report on ZrO2‐supported Pd nanoparticles as a highly active, chemoselective, and reusable catalyst for the hydrogenation–amination of levulinic acid with H2 and various amines under mild reaction conditions. The Pd/ZrO2 catalyst exhibited a marked increase in activity compared with conventional Pd catalysts and a significant enhancement in pyrrolidone selectivity. The excellent catalytic performances are reasonably attributed to the ZrO2 support, which has strong Lewis acidity to enhance the hydrogenation–amination reaction and hinder side reactions.

Enhancement of Catalytic Activity in Epoxide Hydration by Increasing the Concentration of Cobalt(III)/Salen in Porous Polymer Catalysts

The rational design of catalytic materials from the reaction characteristics is expected to be a useful strategy to create highly efficient catalysts. Herein, according to a well‐established reaction pathway of epoxide hydration catalyzed a dual‐molecular system of Co3+/salen in which a high concentration of active sites is favorable to enhance the activity, we provide an alternative way to prepare a highly efficient heterogeneous catalyst with a high concentration of Co3+/salen from the polymerization of vinyl‐functionalized salen monomers followed by the loading of Co3+ species (Co3+/POL‐salen). Co3+/POL‐salen has a hierarchical porosity and an extraordinary hydrothermal stability. Importantly, catalytic tests in epoxide hydration demonstrate that Co3+/POL‐salen affords excellent high activities, which are even better than those of the homogeneous version. This phenomenon is related to the very high concentration of Co3+/salen in the catalyst. In addition, this catalyst can be recycled readily because of its excellent hydrothermal stability.

A Pd-metalated porous organic polymer as a highly efficient heterogeneous catalyst for C–C couplings

Abstract An efficient catalyst system based on a Pd-metalated porous organic polymer bearing phenanthroline ligands was designed and synthesized. This catalyst was applied to various C–C bond-forming reactions, including the Suzuki, Heck and Sonogashira couplings, and afforded the corresponding products while exhibiting excellent activities and selectivities. More importantly, this catalyst can be readily recycled. These features show that such catalysts have significant potential applications in the future.