Selective Increase in CO2 Electroreduction to Ethanol Activity at Nanograin-Boundary-Rich Mixed Cu(I)/Cu(0) Sites via Enriching Co-Adsorbed CO and Hydroxyl Species.

Selective producing ethanol from CO2 electroreduction is highly demanded, yet the competing ethylene generation route is commonly more thermodynamically preferred. Herein, we reported an efficient CO2-to-ethanol conversion (53.5% faradaic efficiency at -0.75 V versus reversible hydrogen electrode (vs. RHE)) over an oxide-derived nanocubic catalyst featured with abundant "embossment-like" structured grain-boundaries. The catalyst also attains a 23.2% energy efficiency to ethanol within a flow cell reactor. In situ spectroscopy and electrochemical analysis identified that these dualphase Cu(I) and Cu(0) sites stabilized by grain-boundaries are very robust over the operating potential window, which maintains a high concentration of co-adsorbed *CO and hydroxyl (*OH) species. Theoretical calculations revealed that the presence of *OHad not only promote the easier dimerization of *CO to form *OCCO (ΔG ~ 0.20 eV) at low overpotentials but also preferentially favor the key *CHCOH intermediate hydrogenation to *CHCHOH (ethanol pathway) while suppressing its dehydration to *CCH (ethylene pathway), which is believed to determine the remarkable ethanol selectivity. Such imperative intermediates associated with the bifurcation pathway were directly distinguished by isotope labelling in situ infrared spectroscopy. Our work promotes the understanding of bifurcating mechanism of CO2ER-to-hydrocarbons more deeply, providing a feasible strategy for the design of efficient ethanol-targeted catalysts.

One-pot solvothermal synthesis of In-doped amino-functionalized UiO-66 Zr-MOFs with enhanced ligand-to-metal charge transfer for efficient visible-light-driven CO2 reduction.

Metal organic frameworks (MOFs) with high porosity and highly tunable physical/chemical properties can serve as heterogeneous catalysts for CO2 photoreduction, but the application is hindered by the large band gap (Eg) and insufficient ligand-to-metal charge transfer (LMCT). In this study, a simple one-pot solvothermal strategy is proposed to prepare an amino-functionalized MOF (aU(Zr/In)) featuring an amino-functionalizing ligand linker and In-doped Zr-oxo clusters, which enables efficient CO2 reduction driven with visible light. The amino functionalization leads to a significant reduction of Eg as well as a charge redistribution of the framework, allowing the absorption of visible light and the efficient separation of photogenerated carriers. Furthermore, the incorporation of In not only promotes the LMCT process by creating oxygen vacancies in Zr-oxo clusters, but also greatly lowers the energy barrier of the intermediates for CO2-to-CO conversion. With the synergistic effects of the amino groups and the In dopants, the optimized aU(Zr/In) exhibits a CO production rate of 37.58 ± 1.06 µmol g-1 h-1, outperforming the isostructural University of Oslo-66- and Material of Institute Lavoisier-125-based photocatalysts. Our work demonstrates the potential of modifying MOFs with ligands and heteroatom dopants in metal-oxo clusters for solar energy conversion.

Ligand Conformation Fixation Strategy for Expanding the Structural Diversity of Copper-Tricarboxylate Frameworks and C2H2 Purification Performance Studies.

Structural and functional expansion of metal-organic frameworks (MOFs) is fundamentally important because it not only enriches the structural chemistry of MOFs but also facilitates the full exploration of their application potentials. In this work, by employing a dual-site functionalization strategy to lock the ligand conformation, we designed and synthesized a pair of biphenyl tricarboxylate ligands bearing dimethyl and dimethoxy groups and fabricated their corresponding framework compounds through coordination with copper(II) ions. Compared to the monofunctionalized version, introduction of two side groups can significantly fix the ligand conformation, and as a result, the dual-methoxy compound exhibited a different network structure from the mono-methoxy counterpart. Although only one almost orthogonal conformation was observed for the two ligands, their coordination framework compounds displayed distinct topological structures probably due to different solvothermal conditions. Significantly, with a hierarchical cage-type structure and good hydrostability, the dimethyl compound exhibited promising practical application value for industrially important C2H2 separation and purification, which was comprehensively demonstrated by equilibrium/dynamic adsorption measurements and the corresponding Clausius-Clapeyron/IAST/DFT theoretical analyses.

One-pot solvothermal synthesis of flower-like Fe-doped In2S3/Fe3S4 S-scheme hetero-microspheres with enhanced interfacial electric field and boosted visible-light-driven CO2 reduction.

S-scheme heterojunctions hold great potential for CO2 photoreduction into solar fuels, but their activities are severely limited by the low efficiency of interfacial charge transfer. In this work, a facile one-pot solvothermal reaction has been developed to dope Fe into flower-like In2S3/Fe3S4 hetero-microspheres (Fe-In2S3/Fe3S4 HMSs), which are demonstrated as an efficient S-scheme photocatalyst for visible-light-driven CO2 photoreduction. The doping of Fe not only reduces the bandgap of In2S3 and thus extends the optical response to the visible-light region, but also increases the densities of donors and sulfur vacancies, which leads to an elevated Fermi level (Ef). The difference of Ef between In2S3 and Fe3S4 is enlarged and their band bending at the interface is therefore enhanced, which results in promoted carriers transfer in the S-scheme pathway due to the reinforced interfacial electric field. Moreover, Fe-doped In2S3 reduces the formation energy of the *CO intermediate, which thermodynamically favors the CO evolution at the surface. As a result, the Fe-In2S3/Fe3S4 HMSs exhibit a significantly boosted CO2 photoreduction activity in comparison with bare In2S3 and Fe-In2S3 samples. This work demonstrates the great potential of heteroatom-engineered S-scheme photocatalysts for CO2 photoreduction.

[Two new sesquiterpenes in Qi-nan Aquilariae Lignum Resinatum].

This study aimed to investigate the chemical constituents of supercritical extract from Qi-nan Aquilariae Lignum Resinatum by silica gel column chromatography, thin-layer chromatography, and semi-preparative high-performance liquid chromatography. One new elemane-type and one new eudesmane-type sesquiterpene compounds were isolated from the extract, and their structures were identified by MS, UV, IR, NMR, and ECD spectroscopic techniques, and named aquqinanol C(1) and aquqinanol D(2). Both compounds are novel compounds. The neuroprotective effect of the compounds on CORT-induced PC12 cell damage was determined in vitro. The results showed that compounds 1 and 2 exhibited a certain protective effect against CORT-induced damage in PC12 cells.

Substituent Engineering-Enabled Structural Rigidification and Performance Improvement for C2/CO2 Separation in Three Isoreticular Coordination Frameworks.

Construction of porous solid materials applied to the adsorptive removal of CO2 from C2 hydrocarbons is highly demanded thanks to the important role C2 hydrocarbons play in the chemical industry but quite challenging owing to the similar physical parameters between C2 hydrocarbons and CO2. In particular, the development of synthetic strategies to simultaneously enhance the uptake capacity and adsorption selectivity is very difficult due to the trade-off effect frequently existing between both of them. In this work, a combination of the dicopper paddlewheel unit and 4-pyridylisophthalate derivatives bearing different substituents afforded an isoreticular family of coordination framework compounds as a platform. Their adsorption properties toward C2 hydrocarbons and CO2 were systematically investigated, and subsequent IAST and density functional theory calculations combined with column breakthrough experiments verified their promising potential for C2/CO2 separations. Furthermore, the substituent engineering endowed the resulting compounds with simultaneous enhancement of uptake capacity and adsorption selectivity and thus better C2/CO2 separation performance compared to their parent compound. The substituent introduction not only mitigated the framework distortion via fixing the ligand conformation for establishment of better permanent porosity required for gas adsorption but also polarized the framework surface for host-guest interaction improvement, thus resulting in enhanced separation performance.

Theoretical understanding on all-solid frustrated Lewis pair sites of C2N anchored by single metal atom.

The design of all-solid heterogeneous catalysts with frustrated Lewis pairs (FLPs) has attracted much attention recently because of their appealing low dissociation energy for H2 molecules due to which a promotion of hydrogenation reaction is expected. The sterically encumbered Lewis acid (metal site) and base (nitrogen site) in the cavity of single transition metal atom-doped M/C2N sheets make them potential candidates for the design of catalysts with FLPs, while a comprehensive understanding of their intrinsic property and reactivity is still lacking. Calculations show that the complete dissociation of the H2 molecule into two H* states at the N sites requires two steps: heterolytic cleavage of the H2 molecule and the transfer of H* from the metal site to the N site, which are strongly related to the acidity of the metal site. Ni/C2N and Pd/C2N, which outperform the other eight transition metal atom (M) anchored M/C2N candidates, possess low energy barriers for the complete dissociation of H2 molecules, with values of only 0.30 and 0.20 eV, respectively. Furthermore, both Ni/C2N and Pd/C2N catalysts can achieve semi-hydrogenation of C2H2 into C2H4, with overall barriers of 0.81 and 0.75 eV, respectively, which are lower than those reported for many other catalysts. It is speculated that M/C2N catalysts with intrinsic FLPs may also find applications in other important hydrogenation reactions.

Callnudoids A-H: Highly modified labdane diterpenoids with anti-inflammation from the leaves of Callicarpa nudiflora.

Eight undescribed 3,4-seco-norlabdane diterpenoids, callnudoids A-H, as well as two known analogues were isolated from the leaves of Callicarpa nudiflora. The structures were elucidated using spectroscopic methods and were compared with published NMR spectroscopic data. The absolute configurations of callnudoids D and E were defined based on ECD data or single-crystal X-ray diffraction. Callnudoids A-C are the highly modified labdane diterpenoids featuring rearranged 3,4-seco-ring and the formation of an undescribed cyclohexene moiety via C2-C18 cyclization. They only contain 15 carbon atoms on the carbon skeleton. Callnudoid D represents the unusual 3,4-seco-15,16-norlabdane diterpenoid with C13-C17 cyclization, and a putative biosynthesis pathway for callnudoids A, B, D, and E was proposed. All compounds were evaluated for their anti-inflammatory activities by inhibiting the lipopolysaccharide (LPS)-induced nitric oxide (NO) released in RAW264.7 cells; callnudoids A-E and H, and methylcallicarpate obviously inhibited pro-inflammatory cytokines TNF-α and IL-1ß in a dose-dependent manner.

Steering Catalytic Activity and Selectivity of CO2 Photoreduction to Syngas with Hydroxy-Rich Cu2 S@ROH -NiCo2 O3 Double-Shelled Nanoboxes.

Simultaneous transformation of CO2 and H2 O into syngas (CO and H2 ) using solar power is desirable for industrial applications. Herein, an efficient photocatalyst based on double-shelled nanoboxes, with an outer shell of hydroxy-rich nickel cobaltite nanosheets and an inner shell of Cu2 S (Cu2 S@ROH -NiCo2 O3 ), is prepared via a multistep templating strategy. The high performance of Cu2 S@ROH -NiCo2 O3 (7.1 mmol g-1 h-1 for CO; 2.8 mmol g-1 h-1 for H2 ) is attributed to the hierarchical hollow geometry and p-n heterojunction to promote light absorption and charge separation. Spectroscopic and theoretical analyses elucidate that the ROH -NiCo2 O3 surface enhances *CO2 adsorption and lowers energy barriers for CO2 -to-CO. Therefore, modulating the hydroxy contents of ROH -NiCo2 O3 can achieve broad CO/H2 ratios from 0.51 to 1.24. This work offers in-depth insights into adjustable syngas photosynthesis and generalized concepts of selective heterogeneous CO2 photoreduction beyond cobalt-based oxides.

Mechanism of Catalytic Transfer Hydrogenation for Furfural Using Single Ni Atom Catalysts Anchored to Nitrogen-Doped Graphene Sheets.

Catalytic transfer hydrogenation (CTH) of α,ß-unsaturated aldehydes using single metal atom catalysts supported on nitrogen-incorporated graphene sheet (M-Nx-Gr) materials has attracted increasing attention recently, yet the reaction mechanism remains to be explored. Compared to the Ni-N4-Gr model in which the dissociation of isopropanol is highly unfavorable as a result of steric hindrance and inertness of the Ni-N4 site embedded in graphene, the Ni-N3 site in Ni-N3-Gr is more active and facilitates the formation of *H with isopropanol as the H donor, where the dissociation of H from isopropanol with an energy barrier of 0.83 eV is the rate-determining step. An alternative reaction path starts from the coadsorption of isopropanol and furfural molecules at the Ni-N3 site, followed by a direct hydrogen transfer between the two molecules; however, the rate-determining step has a much higher energy barrier of 1.32 eV. Our calculations suggest that the hydrogenation of the aldehyde group is kinetically more favorable than the C═C hydrogenation, revealing the high chemoselectivity of furfural to furfuryl alcohol. Our investigations reveal that the CTH mechanism using the Ni-N3-Gr catalyst is different from that on traditional metal oxides, where the former has only one single active site, while two active sites are required for the latter. The proposed reaction mechanism of CTH for furfural in this study should be helpful to guide the design of single metal atom catalysts with appropriate N coordination for application in chemoselective hydrogenation reactions.

Cadinane-type sesquiterpenoid dimeric diastereomers hibisceusones A-C from infected stems of Hibiscus tiliaceus with cytotoxic activity against triple-negative breast cancer cells.

Three new cadinane-type sesquiterpenoid dimeric diastereomers (1-3) named hibisceusones A-C were obtained from the infected stems of Hibiscus tiliaceus. The structures were determined by NMR spectroscopy and MS techniques, and the absolute configurations were assigned by ECD and single-crystal X-ray diffraction techniques. Compounds 1-3 are diastereomers, and contain a 1,4-dioxane ring linearly fused to different cadinane-type polycyclic skeletons. This is the first time that such a structure has been identified in natural products. Compounds 1-3 exhibited cytotoxic activities, and 2 showed a significantly high anti-triple-negative breast cancer (TNBC) effect. The anti-cancer effect of compound 2 was 3-4 fold higher than that of 1 and 3. The anti-cancer effect was generated via the induction of the apoptosis of the MDA-MB-231 cells by inhibiting the PI3Kα pathway.

Perspective on Defective Semiconductor Heterojunctions for CO2 Photoreduction.

Photocatalytic CO2 reduction to value-added chemicals is a green solution to concurrently address CO2 emission and energy issues, and semiconductor heterojunctions hold great potential to achieve such conversion. However, the photocatalytic performance of the existing heterojunctions is limited by the low interfacial charge transfer efficiency and sluggish surface reaction kinetics. To overcome these obstacles, defect engineering has been applied to heterojunctions to boost CO2 photoreduction in the past 5 years. This perspective summaries the key roles and the related mechanism of various anion vacancies located at the surface, interface, and both surface and interface of heterojunctions in photocatalytic CO2 reduction. Challenges in constructing and characterizating defective heterojunctions as well as in promoting their CO2 photoreduction activity and hydrocarbon selectivity are then outlined. Finally, some solutions to the rational design of defective heterojunctions for efficient and stable CO2 photoreduction are also proposed.

ZnSe Nanorods-CsSnCl3 Perovskite Heterojunction Composite for Photocatalytic CO2 Reduction.

Utilizing sunlight to convert CO2 into chemical fuels could simultaneously address the greenhouse effect and fossil fuel crisis. ZnSe nanocrystals are promising candidates for photocatalysis because of their low toxicity and excellent photoelectric properties. However, pristine ZnSe generally has low catalytic activities due to serious charge recombination and the lack of efficient catalytic sites for CO2 reduction. Herein, a ZnSe nanorods-CsSnCl3 perovskite (ZnSe-CsSnCl3) type II heterojunction composite is designed and prepared for photocatalytic CO2 reduction. The ZnSe-CsSnCl3 type II heterojunction composite exhibits enhanced photocatalytic activity for CO2 reduction with respect to pristine ZnSe nanorods. The experimental characterizations and theoretical calculations reveal that the efficient charge separation and lowered free energy of CO2 reduction facilitate the CO2 conversion on the ZnSe-CsSnCl3 heterojunction composite. This work presents a type II heterojunction composite photocatalyst based on ecofriendly metal chalcogenides and metal halide perovskites. Our study has also promoted the understanding of the CO2 reduction mechanisms on perovskite nanocrystals, which could be valuable for the development of metal halide perovskite photocatalysts.

Cadinane-Type Sesquiterpenoids with Cytotoxic Activity from the Infected Stems of the Semi-mangrove Hibiscus tiliaceus.

Eight new cadinane sesquiterpenoids (1-8), along with two known compounds (9 and 10), were isolated from infected stems of the semi-mangrove plant, Hibiscus tiliaceus. The structures of compounds 1-8 were elucidated through the analysis of their 1D and 2D NMR and MS data, and their absolute configurations were determined by comparing their experimental and calculated ECD spectra and by single-crystal X-ray diffraction. The two confused known compounds (9 and 10) were resolved using single-crystal X-ray crystallography. Compounds 1-3 have novel norsesquiterpene carbon skeletons arising from a ring contraction rearrangement. All obtained isolates were evaluated against the HepG2 and Huh7 cell lines, and compounds 1b, 2b, 4, 6, and 8 showed cytotoxic activity toward both cell lines, with IC50 values ranging from 3.5 to 6.8 µM.

Single non-noble metal atom doped C2N catalysts for chemoselective hydrogenation of 3-nitrostyrene.

Improving the reaction selectivity and activity for challenging substrates such as nitroaromatics bearing two reducible functional groups is important in industry, yet remains a great challenge using traditional metal nanoparticle based catalysts. In this study, single metal atom doped M-C2N catalysts were theoretically screened for selective hydrogenation of 3-nitrostyrene to 3-vinylaniline with H2 as the H-source. Among 20 M-C2N catalysts, the non-noble Mn-C2N catalyst was found to have excellent reaction selectivity. Importantly, due to the solid frustrated Lewis pair sites in the pores of Mn-C2N, a low H2 activation energy is achieved on high-spin Mn-C2N and the rate-determining step for the hydrogenation reactions is the H diffusion from the metal site to the N site. The unraveled mechanism of the hydrogenation of 3-nitrostyrene using Mn-C2N enriches the applications of Mn based catalysts and demonstrates its excellent properties for catalyzing the challenging hydrogenation reaction of substrates with two reducible functional groups.

Improving Ethane/Ethylene Separation Performance of Isoreticular Metal-Organic Frameworks via Substituent Engineering.

The preferential capture of ethane (C2H6) over ethylene (C2H4) presents a very cost-effective and energy-saving means applied to adsorptive separation and purification of C2H4 with a high product purity, which is however challenged by low selectivity originating from their similar molecular sizes and physical properties. Substituent engineering has been widely employed for selectivity regulation and improvement, but its effect on C2H6/C2H4 separation has been rarely explored to date. In this work, four isoreticular coordination framework compounds based on 5-(pyridin-3-yl)isophthalate ligands bearing different substituents were rationally constructed. As revealed by isotherm measurements, thermodynamic studies, and IAST computations, they exhibited promising utility for C2H6/C2H4 separation with moderate adsorption heat and a high uptake amount at a relatively low-pressure domain. Furthermore, the C2H6/C2H4 separation potential can be finely tuned and optimized via purposeful substituent alteration. Most remarkably, functionalization with a nonpolar methyl group yielded an improved separation efficiency compared to its parent compound. This work offers a good reference value for enhancing the C2H6/C2H4 separation efficiency of MOFs by engineering the pore microenvironment and dimensions via substituent manipulation.

Hepatic perivascular epithelioid cell tumor: Clinicopathological analysis of 26 cases with emphasis on disease management and prognosis.

BACKGROUND: Perivascular epithelioid cell tumor (PEComa) is an uncommon tumor of mesenchymal origin. Cases of PEComa in the liver are extremely rare. AIM: To analyze the clinicopathological features and treatment of hepatic PEComa and to evaluate the prognosis after different treatments. METHODS: Clinical and pathological data of 26 patients with hepatic PEComa were collected. All cases were analyzed by immunohistochemistry and clinical follow-up. RESULTS: This study included 17 females and 9 males, with a median age of 50 years. Lesions were located in the left hepatic lobe in 13 cases, in the right lobe in 11, and in the caudate lobe in 2. The median tumor diameter was 6.5 cm. Light microscopy revealed that the tumor cells were mainly composed of epithelioid cells. The cytoplasm contained heterogeneous eosinophilic granules. There were thick-walled blood vessels, around which tumor cells were radially arranged. Immunohistochemical analysis of pigment-derived and myogenic markers in PEComas revealed that 25 cases were HMB45 (+), 23 were Melan-A (+), and 22 SMA (+). TFE3 and Desmin were negative in all cases. All the fluorescence in situ hybridization samples were negative for TFE3 gene break-apart probe. Tumor tissues were collected by extended hepatic lobe resection or simple hepatic tumor resection as the main treatments. Median follow-up was 62.5 mo. None of the patients had metastasis or recurrence, and there were no deaths due to the disease. CONCLUSION: Hepatic PEComa highly expresses melanin and smooth muscle markers, and generally exhibits an inert biological behavior. The prognosis after extended hepatic lobe resection and simple hepatic tumor resection is semblable.

Structural Revisions of Two Highly Aromatic Naphthoquinone-Derived Dimers Based on NMR Analysis, Computer-Assisted Structure Elucidation Methods, and Computations.

Eleucanainones A and B are two structurally complex naphthoquinone-derived dimers whose structure identification is difficult. Large yellow fragments of the preliminary CASE (computer-assisted structure elucidation) analysis revealed that the original structures might be questionable. Structural revisions of the two compounds were proposed on the basis of NMR analysis, CASE methods, conformation analysis, and DFT (density functional theory) NMR calculations with a custom DP4+ analysis. In addition, a polyketide-folded biosynthetic pathway of the two revised structures was proposed.

Atomically Dispersed Vanadium Sites Anchored on N-Doped Porous Carbon for the Efficient Oxidative Coupling of Amines to Imines.

Single-atom catalysts effectively integrate the respective advantages of homogeneous and heterogeneous catalysts and are a pioneering research frontier in catalysis by virtue of their maximized utility of metal atoms and distinct atomic configuration. However, development of such catalysts is still in the early stages. Herein, atomically dispersed vanadium (V) sites that are coordinated by N atoms and inlaid within N-incorporated porous carbon networks were prepared through a top-down strategy by annealing a V-containing metal-organic framework, NH2-MIL-101(V), followed by acid etching. The resulting V-N-C-600 catalyst exhibits unexpected catalytic reactivity, selectivity, and robust stability for the direct aerobic oxidation of benzylamine to generate N-benzylidene benzylamine with molecular oxygen under mild conditions. The turnover frequency reaches 53.9 h-1, which is much superior to those achieved over the commercial V2O5 and state-of-the-art non-noble metal heterogeneous catalysts reported in the literature. Kinetic analysis reveals a low activation energy barrier (37 kJ mol-1) for the benzylamine oxidation and indicates that a carbocationic intermediate is involved in the reaction mechanism. The synergistic effect between the isolated V single-atomic sites and N-doped hierarchically porous carbon network boosts the performance of V-N-C-600. Moreover, V-N-C-600 exhibits a wide generality for the efficient synthesis of a set of symmetrical imines, unsymmetrical imines, and imine derivatives.

Two novel diterpenes from the stems and leaves of tropical seagrass Enhalus acoroides in the South China sea.

Two novel diterpenes Enhoidin A (1) and Enhoidin B (2) featuring an unusual gibberellane skeleton were isolated from the stems and leaves of Enhalus acoroides. Their structures were elucidated on the basis of spectroscopic analysis including 1D and 2D NMR techniques and HR-ESI-MS. This is the first time that this type of lactone ring between C-18 and C-20 has been found among gibberellanes from the tropical seagrasses. Evaluation of the all compounds for cytotoxicity against four human cancer cell lines (MCF-7, HCT-116, HepG-2 and HeLa), and showed moderate cytotoxic activities.