Chemical Constituents from the Leaves of Ligustrum robustum and Their Bioactivities

The leaves of Ligustrum robustum have been consumed as Ku-Ding-Cha for clearing heat and removing toxins, and they have been used as a folk medicine for curing hypertension, diabetes, and obesity in China. The phytochemical research on the leaves of L. robustum led to the isolation and identification of two new hexenol glycosides, two new butenol glycosides, and five new sugar esters, named ligurobustosides X (1a), X₁ (1b), Y (2a), and Y₁ (2b) and ligurobustates A (3a), B (3b), C (4b), D (5a), and E (5b), along with seven known compounds (4a and 6–10). Compounds 1–10 were tested for their inhibitory effects on fatty acid synthase (FAS), α-glucosidase, and α-amylase, as well as their antioxidant activities. Compound 2 showed strong FAS inhibitory activity (IC₅₀ 4.10 ± 0.12 μM) close to that of the positive control orlistat (IC₅₀ 4.46 ± 0.13 μM); compounds 7 and 9 revealed moderate α-glucosidase inhibitory activities; compounds 1–10 showed moderate α-amylase inhibitory activities; and compounds 1 and 10 displayed stronger 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) ammonium salt (ABTS) radical scavenging effects (IC₅₀ 3.41 ± 0.08~5.65 ± 0.19 μM) than the positive control l-(+)-ascorbic acid (IC₅₀ 10.06 ± 0.19 μM). This study provides a theoretical foundation for the leaves of L. robustum as a functional tea to prevent diabetes and its complications.     

分子识别在纳米材料组装中的应用

分子识别应用于纳米材料组装中的研究正受到人们的广泛关注,并逐渐成为超分子化学研究领域中的一个热点。本文对近年来利用分子识别实现纳米材料的组装及可控组装的研究工作进行了综述,并对该领域的研究前景进行了展望。     

Themed Issue on Graphdiyne

Graphdiyne(GDY)has characteristics of one-atom-thick two-dimensional layers comprising of sp and sp2 hybridized carbon atoms.The chemical and electronic structure gives GDY many unique and fascinating properties,such as rich chemical bonds,highly conjugated and super-large π structures,infinitely distributed pores and high inhomogeneity of charge distribution,etc.     

Surface modification boosts exciton extraction in confined layered structure for selective oxidation reaction

Science China Chemistry - Extracting photogenerated species from bulk to surface is an essential process for gaining efficient semiconductor-based photocatalysis. However, compared with charged...     

计算机Monte Carlo法模拟自由基交联共聚网络结构的增长

本文成功地用MonteCarlo方法模拟了以画面方式表示的苯乙烯-二乙烯苯交联共聚反应中大分子链增长、支化及交联的进化情况，并给出了相应的转化率，以定量模型的方式描述了该类反应。     

Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

In this work, Au-modified F-TiO₂ is developed as a simple and efficient photocatalyst for H₂O₂ production under ultraviolet light. The Au/F-TiO₂ photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H₂O₂ synthesis, as in a pure TiO₂ reaction system. The F⁻ modification inhibits the H₂O₂ decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H₂O₂ production. We compared the activity of TiO₂ with F⁻ modification and without F⁻ modification in the presence of Au, and found that the H₂O₂ production rate over Au/F-TiO₂ reaches four times that of Au/TiO₂. In situ electron spin resonance studies have shown that H₂O₂ is produced by stepwise single-electron oxygen reduction on the Au/F-TiO₂ photocatalyst.     

Hydrothermal synthesis, characterization and thermochemistry of Ca2[B2O4(OH)2]·0.5H2O

A pure calcium borate Ca₂[B₂O₄(OH)₂]·0.5H₂O has been synthesized under hydrothermal condition and characterized by XRD, FT-IR and TG as well as by chemical analysis. The molar enthalpy of solution of Ca₂[B₂O₄(OH)₂]·0.5H₂O in HC1·54.582H₂O was determined. From a combination of this result with measured enthalpies of solution of H₃BO₃ in HC1·54.561H₂O and of CaO in (HCl + H₃BO₃) solution, together with the standard molar enthalpies of formation of CaO(s), H₃BO₃(s) and H₂O(l), the standard molar enthalpy of formation of −(3172.5 ± 2.5) kJ mol⁻¹ of Ca₂[B₂O₄(OH)₂]·0.5H₂O was obtained.     

Lead-free Perovskite Materials (NH4)3Sb2IxBr9−x

A family of perovskite light absorbers (NH₄)₃Sb₂I_xBr_9−x (0≤x≤9) was prepared. These materials show good solubility in ethanol, a low-cost, hypotoxic, and environmentally friendly solvent. The light absorption of (NH₄)₃Sb₂I_xBr_9−x films can be tuned by adjusting I and Br content. The absorption onset for (NH₄)₃Sb₂I_xBr_9−x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH₄)₃Sb₂I₉ single crystals were prepared, exhibiting a hole mobility of 4.8 cm² V⁻¹ s⁻¹ and an electron mobility of 12.3 cm² V⁻¹ s⁻¹. (NH₄)₃Sb₂I₉ solar cells gave an open-circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.     

Valency‐Controlled Framework Nucleic Acid Signal Amplifiers

Weak ligand–receptor recognition events are often amplified by recruiting multiple regulatory biomolecules to the action site in biological systems. However, signal amplification in in vitro biomimetic systems generally lack the spatiotemporal regulation in vivo. Herein we report a framework nucleic acid (FNA)‐programmed strategy to develop valence‐controlled signal amplifiers with high modularity for ultrasensitive biosensing. We demonstrated that the FNA‐programmed signal amplifiers could recruit nucleic acids, proteins, and inorganic nanoparticles in a stoichiometric manner. The valence‐controlled signal amplifier enhanced the quantification ability of electrochemical biosensors, and enabled ultrasensitive detection of tumor‐relevant circulating free DNA (cfDNA) with sensitivity enhancement of 3–5 orders of magnitude and improved dynamic range.