Enantioselective Alkynylation of Trifluoromethyl Ketones Catalyzed by Cation‐Binding Salen Nickel Complexes

Cation‐binding salen nickel catalysts were developed for the enantioselective alkynylation of trifluoromethyl ketones in high yield (up to 99 %) and high enantioselectivity (up to 97 % ee). The reaction proceeds with substoichiometric quantities of base (10–20 mol % KOt‐Bu) and open to air. In the case of trifluoromethyl vinyl ketones, excellent chemo‐selectivity was observed, generating 1,2‐addition products exclusively over 1,4‐addition products. UV‐vis analysis revealed the pendant oligo‐ether group of the catalyst strongly binds to the potassium cation (K⁺) with 1:1 binding stoichiometry (K_a=6.6×10⁵ m ^?1).     

Molecularly Tailored Lithium–Arene Complex Enables Chemical Prelithiation of High‐Capacity Lithium‐Ion Battery Anodes

Prelithiation is of great interest to Li‐ion battery manufacturers as a strategy for compensating for the loss of active Li during initial cycling of a battery, which would otherwise degrade its available energy density. Solution‐based chemical prelithiation using a reductive chemical promises unparalleled reaction homogeneity and simplicity. However, the chemicals applied so far cannot dope active Li in Si‐based high‐capacity anodes but merely form solid–electrolyte interphases, leading to only partial mitigation of the cycle irreversibility. Herein, we show that a molecularly engineered Li–arene complex with a sufficiently low redox potential drives active Li accommodation in Si‐based anodes to provide an ideal Li content in a full cell. Fine control over the prelithiation degree and spatial uniformity of active Li throughout the electrodes are achieved by managing time and temperature during immersion, promising both fidelity and low cost of the process for large‐scale integration.     

Hydrogen‐Bond Free Energy of Local Biological Water

Here, we propose an experimental methodology based on femtosecond‐resolved fluorescence spectroscopy to measure the hydrogen (H)‐bond free energy of water at protein surfaces under isothermal conditions. A demonstration was conducted by installing a non‐canonical isostere of tryptophan (7‐azatryptophan) at the surface of a coiled‐coil protein to exploit the photoinduced proton transfer of its chromophoric moiety, 7‐azaindole. The H‐bond free energy of this biological water was evaluated by comparing the rates of proton transfer, sensitive to the hydration environment, at the protein surface and in bulk water, and it was found to be higher than that of bulk water by 0.4 kcal mol^?1. The free‐energy difference is dominated by the entropic cost in the H‐bond network among water molecules at the hydrophilic and charged protein surface. Our study opens a door to accessing the energetics and dynamics of local biological water to give insight into its roles in protein structure and function.     

A new phenolic compound from Phedimus middendorffianus with antiproliferative activity

Abstract

A new phenolic compound (1) and together with 12 known compounds–eight flavonoids (2?～?9), two phenolic compounds (10 and 11) and two benzoic acid (12 and 13)–were isolated from Phedimus middendorffianus (Maxim.). The structures of all compound were determined on the basis of spectroscopic (MS and NMR) analyses. Compounds 4, 5, 7 and 11?～?13 were showed anti-proliferative activities against MCF-7 than PC-3 cell line. Also compound 12 and 13 showed the significant cytotoxic activities against two cancer cell lines, PC-3 and MCF-7.     

Organic solar cells for indoor power generation

正During last decades, organic solar cells (OSCs) have achieved remarkable advancements via extensive studies on the optimization of photovoltaic donor/acceptor (D/A) materials, device fabrication, and the D/A bulk heterojunction morphologies. Power conversion efficiencies (PCEs) up to～16%for single junction cells and over 17%PCEs were successfully demonstrated for tandem OSC devices [1,2].OSCs may find real industrial applications soon, including     

Synthesis of Isocoumarins through Three‐Component Couplings of Arynes,Terminal Alkynes,and Carbon Dioxide Catalyzed by an NHC–Copper Complex

A copper‐catalyzed multicomponent coupling reaction between in situ generated ortho‐arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The key to this CO₂‐incorporating reaction was the use of a versatile N‐heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three‐component reaction.     

Bent Molecules with a 60° Central Core Angle that Form B7 and B2 Phases

Small‐angle bent‐core liquid‐crystalline (LC) molecules based on a 1,2‐bis(phenylethynyl)benzene central core have been synthesized that form banana smectic phases with a ferroelectric B7–antiferroelectric B2 phase sequence upon cooling. The formation of polar, switchable ferro‐/antiferroelectric banana phases indicates that, despite the low core bend angle of approximately 60°, banana smectic phases are still formed with the bend direction parallel to the layer. This study offers significant evidence that shows bent‐core molecules with a 60° bend angle can form the well‐known B2 and B7 banana phases. Consequently, it may lead to the preparation of a wide variety of novel bent molecules with low bend angles that spontaneously form an LC phase with both polarization and chirality.     

One‐Pot Synthesis and Electrocatalytic Properties of Pd@Pt Core‐Shell Nanocrystals with Tailored Morphologies

Pd@Pt core‐shell nanocrystals consisting of well‐defined Pd nanocube cores and dendritic Pt shells were prepared by a new facile aqueous one‐pot synthetic method. The prepared Pd@Pt nanocrystals exhibited efficient catalytic activity and stability toward methanol electrooxidation, and their catalytic function was highly dependent on their Pt shell thickness due to the different synergism between Pt and Pd.     

Novel Reductive Cleavage Reaction of Thiobenzoates with Samarium Diiodide: Convenient Synthesis of Disulfides

The reductive cleavage of thiobenzoates promoted by samarium diiodide afforded various kinds of disulfides in good yields under mild and neutral conditions.