Recyclable N-Heterocyclic Carbene Porous Coordination Polymers with Two Distinct Metal Sites for Transformation of CO2 to Cyclic Carbonates

Single-component catalysts with integrated multiple reactive centers could work in concert to achieve enhanced activity tailored for specific catalytic reactions, but they remain underdeveloped. Herein, we report the construction of heterogeneous bimetallic porous coordination polymers (PCPs) containing both porphyrin and N-heterocyclic carbene (NHC) metal sites via the coordinative assembly of the NHC functionalities. Three heterobimetallic PCPs (TIPP-Zn-Pd, TIPP-Cu-Pd and TIPP-Ni-Pd) have been prepared to verify this facile synthetic strategy for the first time. In order to establish a cooperative action toward the catalytic CO2 cycloaddition with epoxides, an additional tetraalkylammonium bromide functionality has also been incorporated into these polymeric structures through the N-substituent of the NHC moieties. The resulting heterogeneous bimetallic catalyst TIPP-Zn-Pd exhibits the best catalytic performance in CO2 cycloaddition with styrene oxide (SO) under solvent-free conditions at atmospheric pressure and is applicable to a wide range of epoxides. More importantly, TIPP-Zn-Pd works smoothly and is recyclable in the absence of a cocatalyst under 1.0 MPa of CO2 at 60 °C. This indicates that TIPP-Zn-Pd is quite competitive with the reported heterogeneous catalysts, which typically require a high reaction temperature above 100 °C under cocatalyst-free conditions. Thus, this work provides a new approach to design heterogeneous bimetallic PCP catalysts for high-performance CO2 fixation under mild reaction conditions.

Intermetallic Compound with CuNi Sites for Enhancing the Selectivity of Electrochemical CO2 Conversion

Although single-metal-site (SMS) catalysts have long been explored for the electrochemical CO2 reduction reaction (EC-CO2RR), the reactivity and selectivity of SMS catalysts remain rather low due to the competing hydrogen evolution reaction (HER). To improve the selectivity, in this work, a novel intermetallic particle of CuNi is decorated on the N-doped carbon substrate, which was first precisely fabricated by scarifying the bimetal-doped metal-organic framework (MOF). Thanks to the neighboring synergistic functions of Cu and Ni sites, CuNi/NC prominently boosts the electroreduction of CO2, far more than the SMS catalysts of Cu/NC and Ni/NC. Further, CuNi/NC presents superior selectivity toward CO with faradaic efficiency over a wide range of potentials (surpassing 90% at 0.6-1.0 V vs RHE, up to 98% at 0.6 V vs RHE) and excellent durability. The experimental results and theoretical calculations reveal that the Ni species can be highly activated due to the neighboring Cu species, which considerably facilitates the formation of an intermediate of COOH* and consequently enhances the selectivity of the reduction of CO2 to CO. This work paves a general way to precisely fabricate catalysts with multiple metal species and also demonstrates the significant synergetic efficiency between the neighboring sites to improve the catalytic performance.

Endowing Nanoparticles with High Stability on the Hydrogenation Reaction by the Amino Group-Assisted Strategy

In the field of a heterogeneous industrial catalysis process, the encapsulated structure plays a crucial role in preventing active sites from leaching during the reaction; however, related studies on the strategy to fabricate encapsulated catalysts under control remain rare. Herein, we develop an amino-assisted strategy to construct a highly stable catalyst with core-shell copper nanoparticles (NPs), namely, Cu@NC (NC represents the nitrogen-doped carbon), presenting not only excellent activity but also high durability on the hydrogenation of quinolines even in the large-scale tests, which is very vital in practical application. In contrast, in the absence of the amino group, the Cu NPs were dispersed out of the carbon surface to form Cu/NC, leading to readily lose activity in the recycling tests due to the leaching occurred during the catalytic process. This work offers a promising method to fabricate a stable catalyst to enhance durability in heterogeneous catalysis.

Palladium particles dispersed on hollow structural support improve CO2 conversion

Herein, an effective Pd/NHS catalyst has been designed and facilely synthesized with extraordinary CO2 fixation performance, which is superior to that of Pd/NS catalysts, owing to the hollow structures facilitating mass transfer and product release.

Atomically Dispersed Iron Sites on the Hollow Nitrogen-Doped Carbon Framework with a Highly Efficient Performance on Carbon Dioxide Cycloaddition

The exploration of efficient and low-consumption catalysts for carbon dioxide (CO₂) conversion is desirable yet remains a great challenge. Herein, a novel catalyst composed of a hollow nitrogen-doped carbon framework (HNF) enriched with high-loading (9.8 wt %) atomically dispersed iron sites (defined as Fe_SAs/HNF) has been fabricated by a polymer-assisted strategy. As a result, Fe_SAs/HNF has an excellent performance on the cycloaddition reactions of CO₂ with epoxides (the conversion >96%) under milder conditions because of its ultrahigh loading of atomically dispersed iron sites. This study not only provides an advanced catalyst for driving CO₂ cycloaddition but also furnishes a novel perspective on the rational design of superior catalysts with high-loading active sites for diverse heterogeneous catalytic reactions.

Amino induced high-loading atomically dispersed Co sites on N-doped hollow carbon for efficient CO2 transformation

Herein, a novel strategy has been proposed to design a hollow structure via post-modified N sites coordinating to metal species. As a result, an atomically dispersed Co site catalyst with high loading has been obtained and has shown superb performance in CO₂ cycloaddition to ethylene carbonate. This novel avenue can be extended to other atomically dispersed metal catalysts with high loading.

Electrocatalysis CO2 to Tunable Syngas upon Fe Clusters Catalyst Dispersed on Bamboo-like NCTs

Herein, we report a catalyst of Fe@NBCT with a high performance in electrocatalytic CO₂ to syngas with tunable H₂/CO ratio. Both in situ synchrotron radiation Fourier transform infrared spectra (SR-FTIR) and density functional theory (DFT) calculation proved that the differing N-doping carbon matrix and Fe nanoclusters (NCs) play dramatic roles in tuning the ratio of syngas during the electrocatalytic carbon dioxide reduction reaction (EC-CO₂RR) process.

Zn (II)-Coordination-driven Self-assembled Nanoagents for Multimodal Imaging-Guided Photothermal/Gene Synergistic Therapy

Synergistic photothermal therapy (PTT) with gene therapy (GT) has drawn emerging interest in the improvement of cancer therapeutic efficiency, while the co-delivery of photothermal agents (PTAs) and therapeutic genes by an integrated nanoplatform, with controllability and biodegradability, is still challenging and urgently desired. Herein, a multi-functional metal–organic framework (MOF) based PTT–GT platform (siRNA@PT-ZIF-8) was developed, which was constructed with siRNA, a near-infrared (NIR) responsive organic dye IR780 derivative (IR780-1), and 2-methylimidazole (2-MIM) by a facile one-pot self-assembly method. This “all-in-one” system of siRNA@PT-ZIF-8 enabled not only photothermal/photoacoustic/fluorescence multimodal imaging but also tumor microenvironment responsiveness for specific and on-demand release of therapeutic cargos, overcoming the inherent limitations of free gene or organic PTA molecules (e.g., short blood circulation half-life and weak stability) in conventional PTT and GT. This nanoplatform provides an efficient and safe strategy for cancer theranostics, and the one-step assembly strategy favors personalized formulation design for diverse demands in cancer management.

siRNA@PT-ZIF-8 was prepared by one pot self-assembly for tri-mode imaging guided mild-temperature photothermal synergetic gene therapy.

Atomically Dispersed Copper Catalysts for Highly Selective CO2 Reduction

Support substrates play an important and magical role in the catalysis process. Herein, atomically dispersed CuN3 catalysts supported by two different types of zirconia (defined as CuN3/NC/T-ZrO2 and CuN3/NC/M-ZrO2) have...

A gram-scale fabrication of core–shell copper nanoparticles for efficient hydrogenation of nitroarenes

Herein, a series of core–shell catalysts (defined as Cu@NC/PC) has been designed and synthesized for the first time using a functional polymer assistant strategy.

Highly Efficient and Chemoselective Hydrogenation of Nitro Compounds into Amines by Nitrogen-Doped Porous Carbon-Supported Co/Ni Bimetallic Nanoparticles

A novel Co/Ni bimetallic nanoparticle supported by nitrogen-doped porous carbon (NPC), Co₅/Ni@NPC-700, exhibits high conversion, chemoselectivity, and recyclability in the hydrogenation of 16 different nitro compounds into desired amines with hydrazine hydrate under mild conditions. The synergistic effects of Co/Ni bimetal nanoparticles and the NPC-supported porous honeycomb structure with more accessible active sites may be responsible for the high catalytic hydrogenation performance.

Cu Nanoclusters Anchored on the Metal-Organic Framework for the Hydrolysis of Ammonia Borane and the Reduction of Quinolines

Free-access active sites created and the interaction regulated between them and substrates during the heterogeneous catalysis process are crucial, which remain a great challenge. In this work, in suit reduced to afford naked Cu nanoparticles (NPs) have been anchored on the metal-organic framework (MOF), NH₂-MOF, to form Cu-NH₂-MOF. The strategy can precisely control the Cu NP formation with small size and uniform distribution. The Cu NP properties and MOF advantages have been integrated to create a great catalyst with multiple functions and have resulted in improving the recyclability and superb catalytic activity for the one-pot reduction of heterocycle reactions under mild conditions. The experimental and theoretical calculation results show that the superior performance should be attributed to the framework of NH₂-MOF that provides large caves for substrate enrichment and the stabilization of Cu sites by the -NH₂ group.

Encapsulating Cobalt into N-Doping Hollow Frameworks for Efficient Cascade Catalysis

The development of nonprecious catalysts for hydrogenation of organic molecules is of great importance in heterogeneous catalysis. Herein, we report a series of N-doped hollow carbon frameworks encompassing cobalt nanoparticles (denoted as Co@NHF-900) constructed as a new kind of reusable catalyst for this purpose by pyrolysis of ZIF-8@Co-dopamine under Ar atmospheres. Notably, the framework of ZIF-8 is essential for efficient catalyst by providing a carbon framework to support Co-dopamine. The experimental results reveal that the ZIF-8 renders a large hollow place within the catalysts, allowing the enrichment of the substrate and windows of the hollow structure and the ease of mass transfer of products during the reaction. All of the virtues made Co@NHF-900 a good candidate for hydrogenation of quinolines with high activity (TOF value of 119 h^-1, which is several times than that of akin catalysts) and chemoselectivity.

Design of Binary Cu-Fe Sites Coordinated with Nitrogen Dispersed in the Porous Carbon for Synergistic CO2 Electroreduction

To relieve the green gas emission and involve the carbon neutral cycle, electrochemical reduction of CO₂ attracts more and more attention. Herein, a biatomic site catalyst of Cu-Fe coordinated with the nitrogen, which is doped in the carbon matrix (denoted as Cu-Fe-N₆ -C), is designed. The as-obtained Cu-Fe-N₆ -C exhibits higher performance than that of Cu-N-C and Fe-N-C, owing to bimetallic sites, proving synergistic functions based on different molecules and their interfaces. Cu-Fe-N₆ -C shows high selectivity toward CO, with high Faradaic efficiency (98% at -0.7 V), and maintaining 98% of its initial selectivity after 10 h electrolysis. The experimental results and theoretical calculations reveal that the synergistic catalysis of different metallic sites enlarges the adsorption enthalpy of CO₂ , reducing the activation energy result in generating high selectivity, activity, stability, and low impedance.

Outcome of Epidural Hematoma: Lessons from Solitary Fibrous Tumor/Hemangiopericytoma

BACKGROUND

Intracranial solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is rare. In this report, a case of epidural hematoma (EDH) that eventually evolved into SFT/HPC is presented. We describe the possible association between the 2 diseases, which has not been previously reported.

CASE DESCRIPTION

A 40-year-old man suffered from an EDH in the right parietal area 12 years ago and accepted conservative treatment. Follow-up computed tomography (CT) scan shows that the density of the right EDH gradually changed from uniform slightly lower density to mixed density. A new CT scan revealed an epidural mass extending to the subcutaneous with local bone destruction. An operation was performed via a large right parietal craniotomy, and the final diagnosis was World Health Organization grade III SFT/HPC after histopathologic examination and immunohistochemical verification. The patient died of deterioration of brain disease 3 months after the final diagnosis.

CONCLUSIONS

To our knowledge, this is the first report that HPC occurred in the epidural cavity. We are the first time to describe the possible association between EDH and HPC.

Fe Single Atoms and Fe2O3 Clusters Liberated from N-Doped Polyhedral Carbon for Chemoselective Hydrogenation under Mild Conditions

In the area of catalysis, selective reduction of nitro compounds to amino compounds is a colossal challenge due to the existence of competitive reducible functional groups. Herein, an Fe-based catalyst Fe_SAs/Fe₂O_3ACs/N-doped polyhedral carbon (NPC) has been designed and synthesized. As we expected, compared with Fe_SAs and Fe_NPs, Fe_SAs/Fe₂O_3ACs/NPC shows excellent catalytic performance (turnover frequency up to 1923 h^-1, calculated with nitrobenzene), chemoselectivity, and tolerance during the hydrogenation reaction of nitro compounds under room temperature because of the synergistic effects between Fe_SAs and Fe₂O_3ACs. The theoretical calculations show that Fe_SAs prefers to undergo hydrazine decomposition to generate hydrogen and the Fe₂O_3ACs surface is more active toward the nitrobenzene reduction to aniline.

Ni@PC as a stabilized catalyst toward the efficient hydrogenation of quinoline at ambient temperature

A novel and efficient strategy, namely as starch-assistant-confine, was used to design and rationally construct a series of porous carbons featuring uniform dispersal of Ni@PC-T-h with highly-efficient catalytic hydrogenation of quinoline.

An unprecedented water stable acylamide-functionalized metal–organic framework for highly efficient CH4/CO2 gas storage/separation and acid–base cooperative catalytic activity

HNUST-8 exhibits water stable, efficient CH₄/CO₂ storage and separation, acid–base cooperative catalytic activity in a tandem deacetalization Knoevenagel densation.

Formation of a metal–organic framework with high gas uptakes based upon amino-decorated polyhedral cages

An polyhedra porous MOF, with high selectivity of CO₂ over, being formed by TRZ–Zn layer connected ATPA linker.

Three-dimensional coordination polymers constructed from C2-symmetric linkers of pyridyl dicarboxylate ligands

The existence of nano-tubular channels in structure of 1 is responsible practically for moderate carbon dioxide uptakes at 273 K.

Enhanced water stability of a microporous acylamide-functionalized metal–organic framework via interpenetration and methyl decoration

A microporous acylamide-functionalized MOF with a 2-fold interpenetrated and methyl decorated framework (HNUST-4) exhibits good water stability, high and selective CO₂ uptake at ambient temperature.

Bis[bis-(1-ethyl-benzimidazol-2-ylmeth-yl) ether]cobalt(II) dipicrate dimethyl-formamide disolvate

In the title complex, [Co(C₂₀H₂₂N₄O)₂](C₆H₂N₃O₇)₂·2C₃H₇NO, the Co^II ion is coordinated by two sets of two N atoms and an O atom from two independent tridendate ligands in a distorted octa­hedral coordination environment. There are significant differences between chemically equivalent coordination bond lengths. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds and weak π–π stacking inter­actions [centroid–centroid distance 3.495 (1) Å]. In one of the anions one nitro group is rotationally disordered about the C—N bond with refined occupancies of 0.524 (8) and 0.476 (8).

Bis[1,3-bis-(benzimidazol-2-yl)-2-oxa-propane]cobalt(II) dipicrate acetonitrile tris-olvate

In the title compound, [Co(C₁₆H₁₄N₄O)₂](C₆H₂N₃O₇)₂·3CH₃CN, the Co^II ion is located on a crystallographic twofold rotation axis and is coordinated in a slightly distorted tetra­hedral environment by four N atoms from the two bidentate N-heterocycles. The crystal structure is stabilized by inter­molecular N—H⋯O and N—H⋯N hydrogen bonds. One of the acetonitrile solvent mol­ecules also lies on a twofold rotation axis.

2,6-Bis(1H-benzimidazol--2-yl)pyridine methanol trisolvate

In the title compound, C₁₉H₁₃N₅·3CH₄O, the 2,6-bis­(2-benzimidazol­yl)pyridine mol­ecule is essentially planar with an r.m.s. deviation for all non-H atoms of 0.185 Å. The crystal structure is stabilized by inter­molecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds and weak π⋯π stacking inter­actions with centroid–centroid distances of 3.6675 (16) and 3.6891 (15) Å. The atoms of one of the methanol solvent molecules are disordered over two sites with refined occupancies of 0.606(8) and 0.394(8).

1,3-Bis(1-benzyl-1H-benzimidazol-2-yl)-2-oxapropane

In the title compound, C(30)H(26)N(4)O, the dihedral angle between the two benzimidazole rings is 69.35 (9)°. The dihedral angles between the benzimidazole ring system and the phenyl ring are 76.79 (12) and 86.10 (11)° in the two benzyl-benzimidazole moieties.