Generalized Fourth-Order Decompositions of Imaginary Time Path Integral: Implications of the Harmonic Oscillator

The imaginary time path integral formalism offers a powerful numerical tool for simulating thermodynamic properties of realistic systems. We show that, when second-order and fourth-order decompositions are employed, they share a remarkable unified analytic form for the partition function of the harmonic oscillator. We are then able to obtain the expression of the thermodynamic property and the leading error terms as well. In order to obtain reasonably optimal values of the free parameters in the generalized symmetric fourth-order decomposition scheme, we eliminate the leading error terms to achieve the accuracy of desired order for the thermodynamic property of the harmonic system. Such a strategy leads to an efficient fourth-order decomposition that produces third-order accurate thermodynamic properties for general systems.     

Adatom Defect Induced Spin Polarization of Asymmetric Structures

The spin polarization of carbon nanomaterials is crucial to design spintronic devices. In this paper, the first-principles is used to study the electronic properties of two defect asymmetric structures, Cap-(9, 0)-Def [6, 6] and Cap-(9, 0)-Def [5, 6]. We found that the ground state of Cap-(9, 0)-Def [6, 6] is sextet and the ground state of Cap-(9, 0)-Def [5, 6] is quartet, and the former has a lower energy. In addition, compared with Cap-(9, 0) CNTs, the C adatom on C₃₀ causes spin polarization phenomenon and Cap-(9, 0)-Def [6, 6] has more spin electrons than Cap-(9, 0)-Def [5, 6] structure. Moreover, different adsorb defects reveal different electron accumulation. This finding shows that spin polarization of the asymmetric structure can be adjusted by introducing adatom defects.     

Cucurbit[8]uril-induced diarylethene thermally activated delay fluorescence supramolecular switch for sequential energy transfer

Constructing molecular switches based on supramolecular assembly strategy is a research hotspot. In this work, we constructed an all visible-light-regulated supramolecular photo-switch based on pyridinium-modified diarylethene derivative (DTE-Me) and cucurbit[8]uril (CB[8]). CB[8] not only accelerated the photochromic process under 365 nm ultraviolet light but also shifted the absorption of open formed DTE-Me to the visible region, which led to efficient photocyclization under 450 nm visible light irradiation, while DTE-Me and DTE-Me/CB[7] remained unchanged under the same irradiating condition. Moreover, the complexation with CB[8] could induce the strong thermally activated delayed fluorescence (TADF) of guest molecular at 550 nm, which further shifted to 670 nm through two-step sequential energy transfer with sulforhodamine B (SRB) and Cy5. This energy transfer process could also be regulated with visible light, and the application for information encryption was also demonstrated. This assembly provides a convenient approach to construct all visible light-regulated TADF photo-switch.     

Gold-Catalyzed One-Pot Synthesis of Polyfluoroalkylated Oxazoles from N-Propargylamides Under Visible-Light Irradiation

A gold-catalyzed synthesis of polyfluoroalkylated oxazoles from N-propargylamides under visible-light irradiation has been developed. These reactions display excellent compatibility of radicals and gold catalysts under visible-light irradiation. Mechanistic experiments indicate that polyfluoroalkyl iodides play a dual role in enhanced compatibility of radicals and gold catalysts through assisted protodeauration of vinyl gold and reactivated the gold catalyst. In addition, PPh₃AuNTf₂ not only activates N-propargylamide to generate vinyl gold intermediate, but also greatly promotes homolysis of polyfluoroalkyl iodides under blue light irradiation.     

Cu2O-Catalyzed Conversion of Benzyl Alcohols Into Aromatic Nitriles via the Complete Cleavage of the C≡N Triple Bond in the Cyanide Anion

Nitrogen transfer from cyanide anion to an aldehyde is emerging as a promising method for the synthesis of aromatic nitriles. However, this method still suffers from a disadvantage that a use of stoichiometric Cu(II) or Cu(I) salts is required to enable the reaction. As we report herein, we overcame this drawback and developed a catalytic method for nitrogen transfer from cyanide anion to an alcohol via the complete cleavage of the C≡N triple bond using phen/Cu₂O as the catalyst. The present condition allowed a series of benzyl alcohols to be smoothly converted into aromatic nitriles in moderate to high yields. In addition, the present method could be extended to the conversion of cinnamic alcohol to 3-phenylacrylonitrile.     

Rutin and Quercetin Decrease Cholesterol in HepG2 Cells but Not Plasma Cholesterol in Hamsters by Oral Administration

Rutin (R) and quercetin (Q) are two widespread dietary flavonoids. Previous studies regarding the plasma cholesterol-lowering activity of R and Q generated inconsistent results. The present study was therefore carried out to investigate the effects of R and Q on cholesterol metabolism in both HepG2 cells and hypercholesterolemia hamsters. Results from HepG2 cell experiments demonstrate that both R and Q decreased cholesterol at doses of 5 and 10 µM. R and Q up-regulated both the mRNA and protein expression of sterol regulatory element binding protein 2 (SREBP2), low-density lipoprotein receptor (LDLR), and liver X receptor alpha (LXRα). The immunofluorescence study revealed that R and Q increased the LDLR expression, while only Q improved LDL-C uptake in HepG2 cells. Results from hypercholesterolemia hamsters fed diets containing R (5.5 g/kg diet) and Q (2.5 g/kg diet) for 8 weeks demonstrate that both R and Q had no effect on plasma total cholesterol. In the liver, only Q reduced cholesterol significantly. The discrepancy between the in vitro and in vivo studies was probably due to a poor bioavailability of flavonoids in the intestine. It was therefore concluded that R and Q were effective in reducing cholesterol in HepG2 cells in vitro, whereas in vivo, the oral administration of the two flavonoids had little effect on plasma cholesterol in hamsters.     

A General and Highly Selective Palladium‐Catalyzed Hydroamidation of 1,3‐Diynes

A chemo‐, regio‐, and stereoselective mono‐hydroamidation of (un)symmetrical 1,3‐diynes is described. Key for the success of this novel transformation is the utilization of an advanced palladium catalyst system with the specific ligand Neolephos. The synthetic value of this general approach to synthetically useful α‐alkynyl‐α, β‐unsaturated amides is showcased by diversification of several structurally complex molecules and marketed drugs. Control experiments and density‐functional theory (M06L‐SMD) computations also suggest the crucial role of the substrate in controlling the regioselectivity of unsymmetrical 1,3‐diynes.     

Design,Synthesis and Anticancer Activity of a New Series of N-aryl-N′-[4-(pyridin-2-ylmethoxy)benzyl]urea Derivatives

The development of cancer treatments requires continuous exploration and improvement, in which the discovery of new drugs for the treatment of cancer is still an important pathway. In this study, based on the molecular hybridization strategy, a new structural framework with an N-aryl-N’-arylmethylurea scaffold was designed, and 16 new target compounds were synthesized and evaluated for their antiproliferative activities against four different cancer cell lines A549, MCF7, HCT116, PC3, and human liver normal cell line HL7702. The results have shown seven compounds with 1-methylpiperidin-4-yl groups having excellent activities against all four cancer cell lines, and they exhibited scarcely any activities against HL7702. Among them, compound 9b and 9d showed greatly excellent activity against the four kinds of cells, and the IC₅₀ for MCF7 and PC3 cell lines were even less than 3 μM.     

PtRu bimetallic nanoparticles embedded in MOF-derived porous carbons for efficiently electrochemical sensing of uranium

Journal of Solid State Electrochemistry - PtRu bimetallic nanoparticles embedded in MOF-derived porous carbons (PtRu-PCs) were synthesized by first loading PtRu bimetallic nanoparticles into a...     

Linear Group 13 E≡E Triple Bonds in E2Li62+

The triply bonded heavier main-group compounds have a textbook trans-bent geometry, in contrast to a familiar linear form found for the lightest analogues. Strikingly, the unexpected linear group 13 E≡E triple bonds were herein found in the D_4h-symmetry E₂Li₆²⁺ clusters, and they possess a large barrier (>18.0 kcal/mol) towards the dissociation of Li⁺. The perfectly surrounded Li₄ motifs and two linear coordinated Li atoms strongly suppress the increasing nonbonded electron density of heavier E atoms, making two degenerate π bonds and one multi-center σ bond in linear heavier main-group triple bonds. The surrounding Li₆ motifs not only creates an effective electronic structure to form a linear E≡E triple bond, but the resulting electrostatic interactions account for the highly stable global E₂Li₆²⁺ clusters.