Enhanced Photocatalytic Reduction of CO2 to CO through TiO2 Passivation of InP in Ionic Liquids

A robust and reliable method for improving the photocatalytic performance of InP, which is one of the best known materials for solar photoconversion (i.e., solar cells). In this article, we report substantial improvements (up to 18×) in the photocatalytic yields for CO₂ reduction to CO through the surface passivation of InP with TiO₂ deposited by atomic layer deposition (ALD). Here, the main mechanisms of enhancement are the introduction of catalytically active sites and the formation of a pn‐junction. Photoelectrochemical reactions were carried out in a nonaqueous solution consisting of ionic liquid, 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF₄), dissolved in acetonitrile, which enables CO₂ reduction with a Faradaic efficiency of 99 % at an underpotential of +0.78 V. While the photocatalytic yield increases with the addition of the TiO₂ layer, a corresponding drop in the photoluminescence intensity indicates the presence of catalytically active sites, which cause an increase in the electron‐hole pair recombination rate. NMR spectra show that the [EMIM]⁺ ions in solution form an intermediate complex with CO₂^?, thus lowering the energy barrier of this reaction.     

Cyclometalated Iridium(III) Complexes as Two‐Photon Phosphorescent Probes for Specific Mitochondrial Dynamics Tracking in Living Cells

Five cyclometalated iridium(III) complexes with 2‐phenylimidazo[4,5‐f][1,10]phenanthroline derivatives ( IrL1 – IrL5 ) were synthesized and developed to image and track mitochondria in living cells under two‐photon (750 nm) excitation, with two‐photon absorption cross‐sections of 48.8–65.5 GM at 750 nm. Confocal microscopy and inductive coupled plasma‐mass spectrometry (ICP‐MS) demonstrated that these complexes selectively accumulate in mitochondria within 5 min, without needing additional reagents for membrane permeabilization, or replacement of the culture medium. In addition, photobleaching experiments and luminescence measurements confirmed the photostability of these complexes under continuous laser irradiation and physiological pH resistance. Moreover, results using 3D multicellular spheroids demonstrate the proficiency of these two‐photon luminescent complexes in deep penetration imaging. Two‐photon excitation using such novel complexes of iridium(III) for exclusive visualization of mitochondria in living cells may substantially enhance practical applications of bioimaging and tracking.     

Synthesis,Structural Characterization and Reactivity of a Bis(phosphine)(silyl) Platinum(II) Complex

Treatment of 1,2‐C₆H₄(SiH₃)(SiH₃) ( 1 ) with Pt(dmpe)(PEt₃)₂ (dmpe=Me₂PCH₂CH₂PMe₂) in the ratio of 1:1 leads to the complex {1,2‐C₆H₄(SiH₂)(SiH₂)}Pt^II (dmpe) ( 2 ), which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra‐alkoxy substituted silyl platinum(II) compound ( 3 ). Compounds 2 and 3 are the very rare examples of silyl transition‐metal complexes derived from this chelating hydrosilane ligand. To the best of our knowledge, there are only 6 examples of silyl metal complexes prepared from this ligand with such structural features registered in the Cambridge Structural Database, among them, only one silyl platinum(II) compound is presented. The structures of complexes 2 and 3 were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X‐ray analysis.     

Redox‐Neutral α‐Allylation of Amines by Combining Palladium Catalysis and Visible‐Light Photoredox Catalysis

An unprecedented α‐allylation of amines was achieved by combining palladium catalysis and visible‐light photoredox catalysis. In this dual catalysis process, the catalytic generation of allyl radical from the corresponding π‐allylpalladium intermediate was achieved without additional metal reducing reagents (redox‐neutral). Various allylation products of amines were obtained in high yields through radical cross‐coupling under mild reaction conditions. Moreover, the transformation was applied to the formal synthesis of 8‐oxoprotoberberine derivatives which show potential anticancer properties.     

Rhodium(I)‐Catalyzed Regiospecific Dimerization of Aromatic Acids: Two Direct CH Bond Activations in Water

2,2′‐Diaryl acids are key building blocks for some of the most important and high‐performance polymers such as polyesters and polyamides (imides), as well as structural motifs of MOFs (metal–organic frameworks) and biological compounds. In this study, a direct, regiospecific and practical dimerization of simple aromatic acids to generate 2,2′‐diaryl acids has been discovered, which proceeds through two rhodium‐catalyzed C? H activations in water. This reaction can be easily scaled up to gram level by using only 0.4–0.6 mol % of the rhodium catalyst. As a proof‐of‐concept, the natural product ellagic acid was synthesized in two steps by this method.     

Liquid‐Crystalline Mesogens Based on Cyclo[6]aramides: Distinctive Phase Transitions in Response to Macrocyclic Host–Guest Interactions

Producing macrocyclic mesogens that are responsive to guest encapsulation presents a significant challenge. Cyclo[6]aramides, a type of macrocycle with a hydrogen‐bond‐constrained backbone, exhibit thermotropic lamellar, discotic nematic, hexagonal, and rectangular columnar mesophases over a considerably wide temperature range, including at room temperature. Additionally, cyclo[6]aramides show unusual mesophase transitions from lamellar to hexagonal columnar phase mediated by macrocyclic host–guest (H–G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H–G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid‐crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk‐shaped, near‐planar molecular backbone that facilitates intermolecular π–π stacking and leads to columnar assembly.     

船舶结构优化设计方法的研究进展

船舶结构设计，具有较强的综合性、经验性和创造性。运用经典优化方法加以处理，虽然也取得了一定成果，但要建立真正有效的船舶结构优化设计方法，必须与实际工程特点、现代数学理论以及最新计算机技术有机结合。目前，研究工作已取得了初步进展。本文综述了有关研究情况。     

线型聚能装药的理论研究

本文提出了一端起爆的线型聚能装药射流形成的不定常理论模型。根据这一模型,当金属罩在爆轰波作用下的运动速度为已知时,则不论此速度是否是时间或初始位置的函数,都能得到射流形成时的速度,质量和位置等参数。 按照本文模型,Defourneaux.M.的定常射流形成定常模型是一个简单的特例。我们利用本文的模型对等厚度装药的情况进行了计算,并与实验结果比较,两者符合良好。同时计算结果表明,考虑射流形成的不定常因素,可以较好地解释射流头部的质量堆积和射流内部的反向速度梯度等实验现象。本文的模型可以为线型聚能切割索的设计提供较为准确的理论指导。