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.

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.

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.

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 FeSAs/HNF) has been fabricated by a polymer-assisted strategy. As a result, FeSAs/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.

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.

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.

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.

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.

High Selectivity of Hydrogenation Reaction over Co0.15@C/PC Catalyst at Room Temperature.

In the field of catalysis, material scientists pay much attention to tuning the activity and chemoselectivity of metal nanoparticles. Herein, we design and successfully synthesize a series of Co NPs which show high performance on hydrogenation of nitroarenes with both activity and chemoselectivity. Co0.15@C/PC preferentially activates the -C═O bond over -NO2 in water with ammonia borane (AB); however, when the hydrogen source is changes to hydrazine hydrate (HH), the results are the opposite. The Co-based catalyst exhibits exceptionally high catalytic activity (with a TOF value of 10512 h-1, which is approximately 100 times than the akin catalysts) and chemo-selectivity for the hydrogenation of nitro compounds under mild conditions. Additionally, the catalyst can be separated easily by a magnet and shows prominent stabilit, which means that it can be reused for at least 10 cycles.

Fe/Fe3C Encapsulated in N-Doped Carbon Tubes: A Recyclable Catalyst for Hydrogenation with High Selectivity.

Herein, a series of Fe-based catalysts have been designed and prepared by grinding a mixture of MIL-88d and melamine, and then the mixture was followed by pyrolysis. An unusual Fe/Fe3C-activated site is uniformly encapsulated in the N-doped carbon tubes obtained by pyrolysis of the film-like nanocrystals of MIL-88d. Experimental characterizations and theoretical calculations demonstrate that the surface N sites can effectively trap the nitrobenzene and aniline by their phenyl groups with the formation of three C-N bonds that made the catalyst exhibit excellent catalytic activity (turnover frequencies of ≤11268 h-1 calculated on the basis of nitrobenzene) and chemoselectivity for the reduction of nitro derivatives under facile conditions.

Expanded porous MOF-505 analogue exhibiting large hydrogen storage capacity and selective carbon dioxide adsorption.

An expanded 4,4-paddlewheel-connected porous MOF-505-type metal-organic framework (MOF), [Cu2(PDEB)(H2O)2]·xS (NJU-Bai12; NJU-Bai represents the Nanjing University Bai group and S represents noncoordinated solvent molecules) has been designed from a nanosized rectangular diisophthalate linker containing alkyne groups 5,5'-(1,4-phenylenedi-2,1-ethynediyl)bis(1,3-benzenecarboxylic acid). This MOF material possesses permanent microporosity with the highest Brunauer-Emmett-Teller surface area of 3038 m(2)·g(-1) and the largest unsaturated total hydrogen storage capacity of 62.7 mg·g(-1) at 77 K and 20 bar among reported MOF-505 analogues. Additionally, NJU-Bai12 also exhibits excellent carbon dioxide (CO2) uptake capacity (23.83 and 19.85 mmol·g(-1) at 20 bar for 273 and 298 K, respectively) and selective gas adsorption properties with CO2/CH4 selectivity of 5.0 and CO2/N2 selectivity of 24.6 at room temperature.

Formation of a metal-organic framework with high surface area and gas uptake by breaking edges off truncated cuboctahedral cages.

Breaking edges off regular truncated cuboctahedra leads to a metal-organic framework (MOF) with polybenzene topology. This fully characterized MOF with lowest connectivity has the largest BET surface area among interpenetrated MOFs.

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.

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.

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.

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 FeSAs/Fe2O3ACs/N-doped polyhedral carbon (NPC) has been designed and synthesized. As we expected, compared with FeSAs and FeNPs, FeSAs/Fe2O3ACs/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 FeSAs and Fe2O3ACs. The theoretical calculations show that FeSAs prefers to undergo hydrazine decomposition to generate hydrogen and the Fe2O3ACs surface is more active toward the nitrobenzene reduction to aniline.

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.

Bronchogenic Cyst: Skull Base Lesions with Extracranial Extension.

BACKGROUND: Intracranial bronchogenic cysts (BCs) are extremely rare. To our knowledge, this is the first report of a BC in which lesions involve the middle and posterior cranial fossa, as well as the infratemporal fossa. CASE DESCRIPTION: We present the case of a 38-year-old woman who suffered from a cranial nerve dysfunction for 2 years. Magnetic resonance imaging showed that there were skull base communication lesions across the middle and posterior fossa. The patient was operated on through an infratemporal fossa approach. The final diagnosis was BC after histopathologic examination and immunohistochemical verification. The patient's neurologic dysfunction was partially ameliorated at the half-year follow-up. CONCLUSIONS: Intracranial BCs are rare. However, they should be considered in the differential diagnosis for cystic lesions with edge enhancement or extracranial extension.

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

In the title complex, [Co(C(20)H(22)N(4)O)(2)](C(6)H(2)N(3)O(7))(2)·2C(3)H(7)NO, 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 octa-hedral coordination environment. There are significant differences between chemically equivalent coordination bond lengths. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds and weak π-π stacking inter-actions [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).