Unraveling the Role of the d‑Electron Reservoir of ZrNi₃/Al₂O₃ for C–O Breaking during CO Methanation: Zr-Induced Active Sites Make the Difference

According to density functional theory results, ZrNi3/Al2O3 exhibits a higher activity of CO methanation with a decreased Ea of the C–O bond breaking compared to Zr2Ni11 and Zr2Ni11/Al2O3. This phenomenon is attributed to the presence of active, low-coordinated sites of the Zr-promoter and the large electronic perturbations in contact with the Al2O3 support. The calculations demonstrate that the Zr-promoting effect on C–O breaking is due to the synergy between Zr, Ni, and Al2O3, leading to a shift of εd of ZrNi3/Al2O3. This promoting effect is able to reduce the electrical band gap of the CO dissociation by creating a new energy state between the d-state of ZrNi3/Al2O3 and the p-state of CO. Even more, this promoting effect tunes C2p and O2p to higher energy, sufficient to produce the more 2π*-antibonding states, and thus, enough to weaken further the C–O bond resulting in a more reactive CO. More importantly, ZrNi3/Al2O3 activates CO efficiently, prevents the production of CH3OH, and via the direct C–O breaking pathway generates CH4

Unraveling the Role of the d‑Electron Reservoir of ZrNi₃/Al₂O₃ for C–O Breaking during CO Methanation: Zr-Induced Active Sites Make the Difference

According to density functional theory results, ZrNi3/Al2O3 exhibits a higher activity of CO methanation with a decreased Ea of the C–O bond breaking compared to Zr2Ni11 and Zr2Ni11/Al2O3. This phenomenon is attributed to the presence of active, low-coordinated sites of the Zr-promoter and the large electronic perturbations in contact with the Al2O3 support. The calculations demonstrate that the Zr-promoting effect on C–O breaking is due to the synergy between Zr, Ni, and Al2O3, leading to a shift of εd of ZrNi3/Al2O3. This promoting effect is able to reduce the electrical band gap of the CO dissociation by creating a new energy state between the d-state of ZrNi3/Al2O3 and the p-state of CO. Even more, this promoting effect tunes C2p and O2p to higher energy, sufficient to produce the more 2π*-antibonding states, and thus, enough to weaken further the C–O bond resulting in a more reactive CO. More importantly, ZrNi3/Al2O3 activates CO efficiently, prevents the production of CH3OH, and via the direct C–O breaking pathway generates CH4

Highly Enantioselective Michael Addition of Nitroalkanes to Chalcones Using Chiral Squaramides as Hydrogen Bonding Organocatalysts

A series of squaramide-based organocatalysts were facilely synthesized and applied as hydrogen bonding organocatalysts in the enantioselective Michael addition of nitroalkanes to chalcones. These organocatalysts promoted the Michael addition with low catalyst loading under high temperature (80 °C), affording the desired R or S enantiomers of the products flexibly in high yields with excellent enantioselectivities (93−96% ee) by the appropriate choice of organocatalysts

Squaramide–Tertiary Amine Catalyzed Asymmetric Cascade Sulfa-Michael/Michael Addition via Dynamic Kinetic Resolution: Access to Highly Functionalized Chromans with Three Contiguous Stereocenters

An efficient asymmetric cascade sulfa-Michael/Michael addition reaction catalyzed by a chiral bifunctional squaramide–tertiary amine catalyst has been developed. This organocatalytic cascade reaction provides easy access to highly functionalized chromans with three contiguous stereocenters, including one quaternary center. In addition, a novel cascade sulfa Michael/retro-sulfa-Michael/sulfa-Michael/Michael reaction process, involving dynamic kinetic resolution, is described

DataSheet_1_Effects of typhoons on primary production and dissolved oxygen in the East China Sea.docx

Previous investigations confirm that typhoons deliver both dissolved oxygen and nutrient sources via promoting vertical/lateral exchanges between water masses. The former one replenishes oxygen for the bottom water and prevents persistent oxygen depletion, while the latter one facilitates primary production and subsequent subsurface oxygen consumption. However, it is left unknown if typhoons ultimately result in net gain or loss of dissolved oxygen during the passage. Tropical cyclone information, satellite observations, and numerical simulations were used to investigate the response of primary production and dissolved oxygen dynamics to typhoons. Results imply that both typhoon intensity, and distance between typhoon track and the Changjiang estuary control the magnitude of responses in primary production, air-sea oxygen flux, advection-induced oxygen variation, and oxygen consumption variation. The model-based oxygen budget analysis indicated that oxygen content increased after the passage of all typhoons occurred between 2011-2020. The findings in this study suggest that typhoons ultimately result in net gain of oxygen. The increased strength and frequency of typhoon in the warming future would play an important role in counteracting deoxygenation, which is likely to slow down the pace of deterioration of the seasonal hypoxia in this region.</p

Efficient Metal-Free Oxygen Reduction in Alkaline Medium on High-Surface-Area Mesoporous Nitrogen-Doped Carbons Made from Ionic Liquids and Nucleobases

Mesoporous nitrogen-doped carbon materials with high surface areas up to 1500 m2 g−1 were conveniently made by the carbonization of nucleobases dissolved in an all-organic ionic liquid (1-ethyl-3-methylimidazolium dicyanamide). Using hard templating with silica nanoparticles, this process yields high-surface-area nitrogen-doped carbon materials with nitrogen contents as high as 12 wt %, narrow mesopore size distribution of ca. 12 nm diameter, and local graphitic carbon structure. It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells. Specifically, the as-prepared materials exhibit a low onset voltage for ORR in alkaline medium and a high methanol tolerance, compared with those of commercial 20 wt % Pt/C catalyst. We regard this as a first step toward an all-sustainable fuel cell, avoiding noble metals

Rhodium-Catalyzed Remote Isomerization of Alkenyl Alcohols to Ketones

We develop herein an efficient rhodium-catalyzed remote isomerization of aromatic and aliphatic alkenyl alcohols into ketones. This catalytic process, with a commercially available catalyst and ligand ([RhCl­(cod)]2 and Xantphos), features high efficiency, low catalyst loading, good functional group tolerance, a broad substrate scope, and no (sub)­stoichiometric additive. Preliminary mechanistic studies suggest that this transformation involves an iterative dissociative β-hydride elimination–migration insertion process

Palladium-Catalyzed <i>syn</i>-Stereocontrolled Ring-Opening of Oxabicyclic Alkenes with Sodium Arylsulfinates

Palladium-catalyzed syn-stereocontrolled ring-opening reactions of oxabenzonorbornadienes with a wide range of sodium arylsulfinates were investigated, affording the desired products in good to excellent yields under an air atmosphere. This protocol provides a low-cost new viable and convenient method toward the synthesis of cis-2-aryl-1,2-dihydronaphthalen-1-ol with good functional group tolerance. In addition, the cis configuration of 3da was established by X-ray diffraction analysis, and a plausible mechanism for the ring-opening reaction was proposed

Squaramide–Tertiary Amine Catalyzed Asymmetric Cascade Sulfa-Michael/Michael Addition via Dynamic Kinetic Resolution: Access to Highly Functionalized Chromans with Three Contiguous Stereocenters

An efficient asymmetric cascade sulfa-Michael/Michael addition reaction catalyzed by a chiral bifunctional squaramide–tertiary amine catalyst has been developed. This organocatalytic cascade reaction provides easy access to highly functionalized chromans with three contiguous stereocenters, including one quaternary center. In addition, a novel cascade sulfa Michael/retro-sulfa-Michael/sulfa-Michael/Michael reaction process, involving dynamic kinetic resolution, is described

Iridium/Copper Co-catalyzed <i>Anti</i>-Stereoselective Ring Opening of Oxabenzonorbornadienes with Grignard Reagents

Cooperative catalysis has been widely considered as one of the most powerful strategies to improve synthetic efficiency. A new iridium/copper cocatalyst was developed for the ring-opening reaction of oxabenzonorbornadienes with a wide variety of Grignard reagents, which afforded the corresponding <i>anti</i>-2-substituted 1,2-dihydronaphthalen-1-ols in high yields (up to 99% yield) under mild conditions. The effects of catalyst loading, Lewis acid, Grignard reagent loading, and reaction temperature on the yield were investigated. To the best of our knowledge, it represents the first example of ring-opening reactions of oxabicyclic alkenes with Grignard reagent nucleophiles in a <i>trans</i>-stereoselective manner