Synthesis and structural characterization of a novel dimolybdenum(I) compound with mixed‐tribridging ligands: [Bu4N][Mo2(μ‐SPh)2(μ‐Cl(CO6]

A novel mixed‐tribridged dimolybdenum(I) compound [Bn₄N][Mo₂(μ‐SPh)₂(μ‐Cl)(CO)₆] (1) has been synthesized from the reaction of Mo₂(CO)₃(SPh)₂ with BU₄NCl. Compound 1 was characterized by IR, UV‐Vis and ¹H, ¹³C, ⁹⁵Mo NMR spectroscopic analyses. The electrochemical behavior was measured by cyclic voltammetry, indicating a quasi‐reversible two‐electron transfer in one step. The crystal structure determined by X‐ray crystallography shows that 1 contains a [Mo₂(μ‐S)₂(μ‐Cl)]^? core with a planar Mo₂S₂unit and a Cl bridge. The Mo? Mo distance is 0.28709(7) nm, and the Mo‐Cl‐Mo angle is 66.44(4)°. A newface‐sharing bioctahedral structure is discussed.     

Ni对Cu/ZnO基甲醇裂解催化剂的促进机制

通过XRD,BET,In-situ XPS等表征技术对Cu/ZnO基甲醇裂解制氢催化剂进行 了详细的研究。XRD结果表明,Cu-Zn合金的生成是Cu/ZnO基催化剂在反应初期快速 失活的主要原因;XRD,BET和N_2O滴定实验结果表明,Ni助剂可能是通过提高 Cu~0活性物种的分散度并维持Cu~0活性物种在催化反应过程中的稳定性而使 Cu/Zn/Ni催化剂的活性及稳定性大幅度提高。In-situ XPS结果表明,Ni助剂的加 入可以诱导Cu/Zn/Ni催化剂表面在甲醇裂解反应过程中出现Cu~+,从而由 Cu~0/Cu~+共同构成催化剂的活性中心,并最终导致Cu/Zn/Ni催化剂的高活性。     

Preparative isolation of pseudolaric acids A and B,and their glucosides from the root bark of Pseudolarix kaempferi using high‐speed counter‐current chromatography

In order to provide the chemical markers for the quality control of herbal medicines, four diterpenoids, pseudolaric acids A and B (PAA and PAB), and their glucosides were isolated from the methanol extract of the Chinese herb Pseudolarix kaempferi using high‐speed counter‐current chromatography (HSCCC). The diphase solvent system was n‐hexane/EtOAc/MeOH/H₂O which was used at two ratios (5:5:5:5 and 1:9:4:6 by volume) in the separation of pseudolaric acids and their glycosides, respectively. As a result, PAA (14 mg), PAB (129 mg), PAA‐O‐β‐D ‐glucopyranoside (8 mg, PAAG), and PAB‐O‐β‐D ‐glucopyranoside (42 mg, PABG) were obtained from 0.5 g of the crude extract. Their purities were determined to be above 97% by HPLC analysis. Their chemical structures were confirmed by ¹H and ¹³C NMR analysis or HPLC comparison with the reference compounds.     

Photoinduced Oxidation Reaction of Benzotrifluoride with OH Radical by the Laser Flash Method

The optical transient and kinetics characterizations of the transients formed in the reaction of OH with benzotrifluoride (BTF) were performed by a laser flash photolysis technique. The results indicated that the formation of π‐type adduct of C₆H₅(OH)CF₃ was the major reaction channel, and the δ‐type adduct of C₆H₅CF₃OH formation was an additional minor process in the oxidation reaction of BTF attacked by OH radicals yielded from the photolysis of H₂O₂. Addition of OH to the CF₃ group led to the fluoride ion elimination to yield α,α‐difluorophenylcarbinol (C₆H₅CF₂OH). Trifluoromethylphenol (HOC₆H₄CF₃) of meta‐, para‐ and ortho‐substituted isomers resulted from the addition of OH to the BTF aromatic ring.     

New gold(III) chlorophenyl terpyridine complex: Biomolecular interactions and anticancer activity against human oral squamous cell carcinoma

In this work we synthesized new monofunctional gold(III) complex [Au(Cl-Ph-tpy)Cl]Cl₂ (Cl-Ph-tpy = 4′-[4-chlorophenyl]-2,2′:6′, 2″-terpyridine). This complex was characterized by UV–Vis, NMR, IR, and ESI-MS spectrometry. The kinetic study of the substitution reactions of the Au-Cl-Ph-tpy complex with biomolecules showed that the rate constants depend on the nature of the entering nucleophile. Based on the calculated values of entropy (∆H^≠ > 0) and enthalpy (∆S^≠ < 0) the proposed substitution mechanism is associative. Additionally, the relative stability and thermodynamic properties of Au-Cl-Ph-tpy complex were compared with the analogue Au-tpy complex by the B3LYP/def2-svp method. DNA/BSA binding studies showed that Au-Cl-Ph-tpy complex interacts with CT DNA through the intercalation and moderately quenches the fluorescence of tryptophan residues in serum albumin (BSA). Molecular docking confirmed results obtained by spectroscopic experiments and suggested site I (subdomain IIA) for binding of Au complex to BSA. We demonstrated that the Au chlorophenyl terpyridine complex possessed significant in vitro cytotoxic activity against human oral squamous carcinoma cells (CAL-27), induced apoptosis, inhibited proliferation of CAL-27 cells, and induced cell cycle disturbance. Treatment of CAL-27 cells with the Au complex enhanced expression of cyclin-dependent kinase inhibitors p21 and p27, resulting in cell cycle arrest in the G1 phase, reduced the percentage of CAL-27 cells in S phase and decreased expression of Ki-67. Additionally, Au complex reduced expression of phosphorylated STAT3 and downstream regulated molecules associated with cancer stemness, NANOG, and Sox2 protein.     

Targeted Synthesis of Isomeric Naphthalene-Based 2D Kagome Covalent Organic Frameworks

Targeted synthesis of kagome ( kgm ) topologic 2D covalent organic frameworks remains challenging, presumably due to the severe dependence on building units and synthetic conditions. Herein, two isomeric “two-in-one” monomers with different lengths of substituted arms based on naphthalene core (p-Naph and m-Naph) are elaborately designed and utilized for the defined synthesis of isomeric kgm Naph-COFs. The two isomeric frameworks exhibit splendid crystallinity and showcase the same chemical composition and topologic structure with, however, different pore channels. Interestingly, C₆₀ is able to uniformly be encapsulated into the triangle channels of m-Naph-COF via in situ incorporation method, while not the isomeric p-Naph-COF, likely due to the different pore structures of the two isomeric COFs. The resulting stable C₆₀@m-Naph-COF composite exhibits much higher photoconductivity than the m-Naph-COF owing to charge transfer between the conjugated skeletons and C₆₀ guests.     

Physicochemical Properties and Elimination of the Activity of Anti-Nutritional Serine Protease Inhibitors from Mulberry Leaves

Mulberry leaf is an excellent protein resource that can be used as feed additive for livestock and poultry. Nevertheless, the use of mulberry leaves in animal diets is limited by its protease inhibitors, tannic acid and other anti-nutritional factors. This study systematically analyzed the type and activity of serine protease inhibitors (SPIs) from the leaves of 34 mulberry varieties, aiming to reveal the physicochemical properties and inactivation mechanism of SPIs. The types and activities of trypsin inhibitors (TIs) and chymotrypsin inhibitors (CIs) exhibited polymorphisms among different mulberry varieties. The highest number of types of inhibitors was detected in Jinshi, with six TIs (TI-1~TI-6) and six CIs (CI-1~CI-6). TIs and CIs exhibited strong thermal and acid–base stability. High-temperature and high-pressure treatment could reduce the activities of TIs and CIs to a certain extent. β-mercaptoethanol treatment could completely abolish TIs and CIs, suggesting that the disulfide bridges were critical for their inhibitory activities. The Maillard reaction could effectively eliminate the inhibitory activities of TI-1~TI-4 and CI-1~CI-4. This study reveals the physicochemical properties and inactivation mechanisms of the anti-nutritional SPIs from mulberry leaves, which is helpful to exploit mulberry-leaf food with low-activity SPIs, promote the development and utilization of mulberry-leaf resources in animal feed and provide reference for mulberry breeding with different functions.     

Fabrication of a family of atomically precise silver nanoclusters via dual-level kinetic control

The controllable preparation of metal nanoclusters in high yield is an essential prerequisite for their fundamental research and extensive application. Here a synthetic approach termed “dual-level kinetic control” was developed to fabricate a family of new silver nanoclusters. The introduction of secondary ligands was first exploited to retard the reduction rate and accomplish the first-level kinetic control. And the cooling of the reaction was performed to further slow the reduction down and accomplish the second-level kinetic control. A family of atomically precise silver nanoclusters (including [Ag₂₅(SR)₁₈]⁻, [Ag₃₄(SR)₁₈(DPPP)₃Cl₄]²⁺, [Ag₃₆(SR)₂₆S₄]²⁺, [Ag₃₇(SR)₂₅Cl₁]⁺, and [Ag₅₂(SR)₂₈Cl₄]²⁺) were controllably prepared and structurally determined. The developed “dual-level kinetic control” hopefully acts as a powerful synthetic tool to manufacture more nanoclusters with unprecedented compositions, structures, and properties.

A dual-level kinetic control was exploited to fabricate a family of atomically precise silver nanoclusters.     

Determination of pyrethroid pesticide residues in vegetables by solvent sublation followed by high-performance liquid chromatography

A novel method is developed for separating and enriching pyrethroid pesticides from vegetables by solvent sublation, and determination of the pyrethroids is performed by high-performance liquid chromatography (HPLC). The effects of organic solvent, pH of the solution, nitrogen flow rate, and sublation time on the sublation efficiency of pyrethroids are investigated in detail, and the optimal conditions of the solvent sublation are selected. The floated product of vegetables in the optimal conditions is determined by HPLC. The limit of detection values range from 1.4 microg/kg (for bifenthrin) to 4.2 microg/kg (for fenpropathin). The recoveries of spiked vegetable samples are from 85.7% to 110.4%, and relative standard deviation values are from 1.70% to 6.19%. The results are satisfactory.     

Reinforced self-assembly of hexa-peri-hexabenzocoronenes by hydrogen bonds: from microscopic aggregates to macroscopic fluorescent organogels

Hexa-peri-hexabenzocoronene derivatives (HBCs) that have hydrogen-bonding functionalities (either amido or ureido groups) adjacent to the aromatic cores have been synthesized to study the effects of intracolumnar hydrogen bonds on the self-assembly behavior of HBCs. The hydrogen bonds effectively increased the aggregation tendency of these compounds in solution. In the bulk state, the typical columnar supramolecular arrangement of HBCs was either stabilized substantially (1 a, 1 b, 2 a, and 2 b), or suppressed by dominant hydrogen-bonding interactions (3). For some of the compounds (1 a, 2 a, and 2 b), the supramolecular arrangement adopted in the liquid-crystalline state was even retained after annealing, presumably owing to the reinforcement of the pi-stacking interactions by the hydrogen bonds. Additionally, the combined effect of the hydrogen bonds and pi-stacking of the aromatic moieties led to the formation of fluorescent organogels, whereby some derivatives were further investigated as novel low molecular-mass organic gelators (LMOGs).