Acyclic Janus‐AT Nucleoside Host Channels Precisely Lock Water into Single‐File Wires with Local Rotational Flexibility

Confining polar water molecules to particular geometries demands sophisticated intermolecular interactions, and not many small synthetic molecules have accomplished such a task. Herein, regioisomeric acyclic Janus‐AT nucleosides ( 1 and 2 ), with a self‐complementary fused genetic alphabet and conformationally flexible side chains, have been selectively synthesized. 1 and 2 adopt disparate base‐pair motifs from the π–π stacked hydrophobic base moieties and distinct hydrogen bond (HB) interconnections from the hydrophilic sugar residues, which in turn lead to divergent, intricate intermolecular interaction networks with different capacities to confine water molecules. Under the precise control of the host framework of the N⁸‐regioisomer, separate ordered single‐file water wires can be locked through special three‐HB clamps into unique inter‐ and intra‐wire geometrical alignments. Localized dynamic synchronized rotations within the fixed framework coordinated by both the host hydroxy groups and guest water molecules were observed in a temperature‐induced reversible single‐crystal‐to‐single‐crystal transition (SCSCT).     

Structural variation from trinuclears to 1D chains: Syntheses,structures and properties

Five complexes [Co₃(Hpmad)₆]·(4‐sb)₂·(CH₃COO)₂·(H₂O)₂ ( 1 ), [Co₃(Hpmad)₆]·(3‐sb)₂·(CH₃COO)₂·(H₂O)_0.5 ( 2 ), [Co(Hpmad)₂(4‐sb)]_n ( 3 ), [Co(Hpmad)₂(3‐sb)]_n ( 4 ) and {[Co(Hpmad)(SO₄)(H₂O)₂]·H₂O}_n ( 5 ) [Hpmad is 2‐pyrimidineamidoxime, H₂(4‐sb) is 4‐sulfobenzoic acid and H₂(3‐sb) is 3‐sulfobenzoic acid], were prepared at room temperature. Complexes 1 – 5 were characterized by elemental analyses, single crystal X‐ray diffractions, powder X‐ray diffractions, infrared spectra, thermogravimetric analyses, fluorescence spectra and magnetic susceptibility measurements. Complexes 1 and 2 possess the linear trinuclear Co²⁺ structures. Complexes 3 and 4 exhibit similar one‐dimensional (1D) chains. Complex 5 comprises the 1D helical chain. The change of anion in cobalt salt from CH₃COO^? to Cl^? to SO₄^2? leads to the structural evolution from the linear trinuclear Co²⁺ structure to the 1D chain to the 1D helical chain. Complexes 1 – 5 exhibit the Hpmad‐based emissions. The magnetic properties of 1–5 were also investigated.     

Ancillary Ligand Effects on Heteroleptic IrIII Dye in Dye-Sensitized Photocatalytic CO2 Reduction: Photoaccumulation of Charges on Arylated Bipyridine Ligand and Its Control on Catalytic Performance

Herein, we report the synthesis, and photochemical and -physical properties, as well as the catalytic performance, of a series of heteroleptic Ir^III photosensitizers (IrPSs), [Ir(C^N)₂(N^N^Aryl)]⁺, possessing ancillary ligands that are varied with aryl-substituents on bipyridyl unit [C^N=(2-pyridyl)benzo[b]thiophen-3-yl (btp); N^N^Aryl=4,4′-Y₂-bpy (Y=−Ph or −PhSi(Ph)₃]. We found that the π-extension of bipyridyl ligand by aryl-substitution put bipyridyl ligand in use as an electron relay unit that performed charge accumulation before delivering to the catalytic center, greatly improving the overall CO₂-to-CO conversion activities. In a typical run, the aryl-substituted IrPS ( ^{t Bu} IrP-Ph^Si )-sensitized homogeneous systems (IrPS+Re^I catalyst) gave a turnover number of 1340 (Φ_CO=24.2 %) at the early stage of photolysis (<5 h). This study demonstrates that the π-character modulation on the ancillary bipyridyl ligand is critical for forthcoming catalytic performance.     

PVT法AlN单晶生长技术研究进展及其面临挑战

氮化铝(AlN)具有超宽禁带宽度(6.2 eV)、高热导率(340 W/(m·℃))、高击穿场强(11.7 MV/cm)、良好的紫外透过率、高化学和热稳定性等优异性能,是氮化镓基(GaN)高温、高频、高功率电子器件以及高Al组分深紫外光电器件的理想衬底材料.物理气相传输(PVT)法是制备大尺寸高质量AlN单晶最有前途的方法.本文介绍了AlN单晶的晶体结构、基本性质及PVT法生长AlN晶体的原理与生长习性.基于AlN单晶PVT生长策略,综述了自发形核工艺、同质外延工艺及异质外延工艺的研究历程,各生长策略的优缺点及其最新进展.最后对PVT法生长AlN单晶的发展趋势及其面临的挑战进行了简要展望.     

Electrochemical determination of ionization constants of tetrabutylammonium salt in acetonitrile and ο-nitrophenyloctylether

Cyclic voltammetry of ferrocene at glassy carbon electrode in acetonitrile (ACN), ο-nitrophenyloctylether (NPOE) and ACN-NPOE mixture with 0.2 M tetrabutylammonium tetrafluoroborate (TBABF₄) were investigated. Both cathodic and anodic peak current were diffusion-controlled at any NPOE fraction. However, the peak current was decreased with the increasing NPOE fraction. In addition, the peak potential difference increased not only with an increase in the NPOE fraction but also in the scan rate, while the values of half-wave potential did not vary largely with the fraction or the scan rate. This indicated that the variation of peak current and peak potential should be due to the variation of the solution resistance. In order to demonstrate this assumption, the conductance of TBABF₄ in ACN, NPOE, and ACN-NPOE mixture were determined by AC impedance. All of the solution conductances were inversely linear to the viscosity of the solvent, which was increased with the fraction of NPOE. The calculated ionization constant of TBABF₄ in ACN was 2.8 times of that in NPOE. TBABF₄ in ACN can work as a supporting electrolyte, whereas they work partly in NPOE.     

The improved photosensitivity of photosensitive polyimides containing o-nitrobenzyl ether groups induced by the addition of photoacid generator

In this article, photosensitive polyimides (PSPIs) with photosensitive groups, o-nitrobenzyl ether groups (Nb), were successfully synthesized based on 2,2′-dihydroxy benzophenone-3,3′,4,4′-tetracarboxylic dianhydride and on diamine containing ethylene glycol chains (ODA). Also, a series of polyimide (PI), ODA-1-PI, ODA-3-PI, and ODA-5-PI with a number of ethylene glycol chains of 1, 3, and 5 were prepared to investigate the relationship between structure and solubility. Interestingly, ODA-5-PI, which possesses a large number of ethylene glycols, exhibited the most excellent solubility. Therefore, due to the good solubility of ODA-5-PI in organic solvents and alkaline solutions, a PSPI, poly(1,4-phenyleneoxy-3,6,9,12,15-pentaoxaoctane-1,4-phenylene-2,2′-di[2-nitrobenzyloxy]benzophenone-3,3′,4,4′-tetracarboxdiimide), named ODA-5-PSPI, was synthesized by linking Nb, which is a photosensitive group. Aiming at producing positive tone patterns, the synthesized ODA-5-PSPI was exposed to UV irradiation and then to a post-exposure bake. Afterward, it was developed using a 2.38 wt% tetramethylammonium hydroxide solution. Furthermore, a photoacid generator (PAG) was additionally incorporated for a micropatterning process. Notably, in the presence of the PAG, the photocleavage of ODA-5-PSPI occurred not only by the intramolecular rearrangement of Nb but also by its hydrolysis reaction. As a result, due to the synergistic effect of photocleavage, the micropatterning of ODA-5-PSPI with PAG could be clearly obtained with less energy (2.0 J/cm²) compared with that without PAG (3.6 J/cm²). Therefore, through the addition of PAG, the photosensitivity was improved by 45%.     

A novel preventive mechanism of gentamicin‐induced nephrotoxicity by atorvastatin

Atorvastatin (ATO) inhibits the synthesis of nonsteroidal isoprenoid compounds and possesses a pleiotropic effect. However, the detailed mechanism of ATO in preventing gentamicin (GM)‐induced renal injury remains obscure. Although underlying multifaceted mechanisms involving GM‐induced nephrotoxicity were well known, further work on elucidating the essential mechanism was needed. Using a fluorogenic derivatization–liquid chromatography tandem mass spectrometry proteomic method (FD‐LC–MS/MS method), we investigated the effects and mechanisms of ATO treatment on GM‐induced nephrotoxicity in rats. Consequently, 49 differentially expressed proteins were identified. The most significant mechanisms of nephrotoxicity caused by GM were mitochondrial dysfunction, fatty acid metabolism and oxidative stress. Their upstream regulator was found to be PPARα. The proteins involved in GM nephrotoxicity were sodium–hydrogen exchanger regulatory factor (SLC9A3R1), cathepsin V (CTSV), macrophage migration inhibitory factor (MIF) and RhoGDP dissociation inhibitor alpha (ARHGDIA). After ATO intervention, we observed a reversed enrichment pattern of their expression, especially in CTSV and SLC9A3R1 (P‐value<0.05). We predicted that ATO may improve abnormal phospholipid metabolism and phospholipidosis caused by GM and also alleviate cell volume homeostasis and reverse the interference of GM with the transporter. Furthermore, proteomic results also provided clues as to GM‐induced nephrotoxicity biomarkers such as CTSV and transthyretin.