A novel cationic [IrH(THF)(P,N)(imine)] [BAr] catalyst containing a P-stereogenic MaxPHOX ligand is described for the direct asymmetric hydrogenation of N-methyl and N-alkyl imines. This is the first catalytic system to attain high enantioselectivity (up to 94% ee) in this type of transformation. The labile tetrahydrofuran ligand allows for effective activation and reactivity, even at low temperatures. Density functional theory calculations allowed the rationalization of the stereochemical course of the reaction.
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http://dx.doi.org/10.1021/jacs.8b11547 | DOI Listing |
Nat Commun
January 2025
School of Physical Science and Technology, Ningbo University, Ningbo, 315211, China.
The high performance of two-dimensional (2D) channel membranes is generally achieved by preparing ultrathin or forming short channels with less tortuous transport through self-assembly of small flakes, demonstrating potential for highly efficient water desalination and purification, gas and ion separation, and organic solvent waste treatment. Here, we report the construction of vertical channels in graphene oxide (GO) membrane based on a substrate template with asymmetric pores. The membranes achieved water permeance of 2647 L m h bar while still maintaining an ultrahigh rejection rate of 99.
View Article and Find Full Text PDFMagn Reson Imaging
January 2025
Institute of Fluid Mechanics, University of Rostock, Rostock, Germany.
Purpose: To improve the current method for MRI turbulence quantification which is the intravoxel phase dispersion (IVPD) method. Turbulence is commonly characterized by the Reynolds stress tensor (RST) which describes the velocity covariance matrix. A major source for systematic errors in MRI is the sequence's sensitivity to the variance of the derivatives of velocity, such as the acceleration variance, which can lead to a substantial measurement bias.
View Article and Find Full Text PDFOrg Lett
January 2025
Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, 3-3-138 Sumiyoshi-ku, Osaka 558-8585, Japan.
The asymmetric total synthesis of isolinearol, a -dolastane-type diterpenoid that inhibits byssal thread formation by mussels, has been achieved. In the synthesis, the key features include an intramolecular reductive nucleophilic addition using a low-valence titanium species and the direct installation of a ketone side chain. We evaluated their biological activities using the synthetic samples and found the novel inhibitory molecules with a simplified structure exhibit high inhibitory activities against byssus formation and low toxicities.
View Article and Find Full Text PDFMicromachines (Basel)
December 2024
College of Electronic and Electrical Engineering, Henan Normal University, Xinxiang 453600, China.
A novel common-aperture miniaturized antenna with wideband and dual-polarized characteristics is proposed, which consists of a circularly polarized (CP) and a linearly polarized (LP) antenna. The circularly polarized antenna stacked on the upper layer adopts asymmetrical ground and introduces the patch and T-type feed network. On this basis, the meshed reflector structure, which also works as a ground plane for the LP antenna, is added to reduce the influence on circular polarization and achieve directional radiation.
View Article and Find Full Text PDFNat Mater
January 2025
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
Van der Waals materials display rich structural polymorphs with distinct physical properties. An atomistic understanding of the phase-transition dynamics, propagation pathway and associated evolution of physical properties is essential for capturing their potential in practical technologies. However, direct visualization of the rapid phase-transition process is fundamentally challenging due to the inherent trade-offs among atomic resolution, field of view and imaging frame rate.
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