信息拓扑指数与烷烃分子热力学性质的关系

Two topological information indices were constructed based on Randic and Wiener indices, and the values of topological information indices for 85 alkanes were calculated. The thermodynamic properties such as the standard enthalpies of formation, the standard entropies and the standard free energies of formation for these alkanes were also correlated with these topological and information indices. It is found that the thermodynamic properties calculated for both gaseous and liquid states of the 85 alkanes are in excellent agreement with the experimental values through the regression analysis.     

Influence of extractions on physicochemical characterization and bioactivity of Piper nigrum oils: Study on the non-isothermal decomposition kinetic

Black pepper oils have been investigated frequently in the recent years. However, there is a significant variation in physicochemical properties and bioactivity of oils depended on extraction techniques. In this study, the systemic investigation of four various extraction methods was performed to evaluate the physicochemical characterizations, antioxidant and antibacterial activity. The investigation of ¹H NMR, FTIR and UV–Vis spectra confirmed presence of non-volatile components in oils extracted through supercritical CO₂ and hexane-soaking extractions which induced their typical thermal properties. The isothermal behaviour of extracted oils related to evaporation was within range of 3.2–7.3% (w/w) at 27 °C. The SEM images of the black pepper confirmed different operation manners of mechanism between extractions using the solvents and heating process. The lowest MIC for both essential oils from conventional hidrodistillation and microwave-assisted hidrodistillation against two bacteria including E. coli and B. subtilis were found to be 137 µg mL⁻¹. The non-isothermal decomposition kinetics were investigated on the essential oil of microwave-assisted hydrodistillation extraction. The activation energies and pre-exponent factors of non-isothermal decomposition were found to be in range of 36.5–73.7 KJ mol⁻¹ and 4.98 × 10³–1.97 × 10⁸ s⁻¹, respectively, dependent on conversional fractions of the oil. The results revealed that chemical components, physicochemical properties and bioactivity of black pepper essential oils depended on the extraction techniques.     

Optimized POCl3-assisted synthesis of 2-amino-1,3,4-thiadiazole/1,3,4-oxadiazole derivatives as anti-influenza agents

Although recent decades have witnessed the synthesis of 1,3,4-thiadiazoles via phosphorus POCl₃-promoted cyclization reaction, simultaneous access to 2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-oxadiazole analogs remains unexpected and elusive. Herein, a detailed regiocontrolled synthesis of 2-amino-1,3,4-thiadiazoles in good to high yields with good regioselectivities from readily available thiosemicarbazides using POCl₃ was disclosed. Meantime, to establish a comprehensive structure–activity relationship, 2-amino-1,3,4-oxadiazole derivatives as single regioisomers were prepared via EDCI·HCl-triggered cyclization of the thiosemicarbazide intermediates. The in vitro anti-influenza assays proved that the selected compounds with the pyrazine/pyridine ring exhibited certain inhibitory activities against influenza A virus strains A/HK/68 (H3N2) and A/PR/8/34 (H1N1) in MDCK cells. Among them, N-(adamantan-1-yl)-5-(5-(azepan-1-yl)pyrazin-2-yl)-1,3,4-thiadiazol-2-amine (4j) was the most active compound, and exhibited favorable activity with EC₅₀ values of 3.5 μM and 7.5 μM, respectively. In addition, the molecular docking results explained the reason why compound 4j had dual inhibitory activity and revealed the reasonable binding mode of this compound with the M2-S31N and M2-WT ion channels. This compound had the potential to be further developed as an anti-influenza drug.     

醇在α-A12O3和硅胶G表面上的脱附规律

吸附质在两相界面上的吸附行为对多相催化、界面化学等有重要意义[1,2]。本文采用程序升温法分别测定了13种醇在α Al2O3和硅胶G表面上的脱附温度td,发现td与醇的沸点及烷基化效应指数[3](PEI)有定量关系。1　实验红外干燥箱100℃干燥30分钟后的吸附剂在所研究的吸附质的饱和蒸汽压、室温下平衡24-48h,以达到吸附平衡;取20-25mg吸附平衡后的吸附剂,用PCT 1A型差热天平进行TG/DTA分析,升温速率为2 5℃/min,升温范围从室温到250℃,由计算机进行数据采集(RSZ 200热分析系统软件),从DTA曲线的最高峰值确定脱附温度,每个样品重复3-5…     

The role of electric interactions in the retention index concept; Implications in quantitative structure-retention studies

Summary A new equation is derived relating the retention index to the molecular polarizabilities, ionization potentials and permanent dipole moments of the stationary phase and the solute.Various implications of this equation to quantitative structure-retention relationships are discussed.     

脂肪胺结构与密度和折光指数关系的探讨

本文用拓扑方法探讨了脂肪胺的密度和折光指数与其分子结构之间的关系。提出一个既适用于密度又适用于折光指数的定量关系。应用这一定量关系, 不仅能够描述脂肪胺密度和折光指数的变化规律。预测脂肪胺的密度和折光指数,而且能够合理表征物质结构与性能之间的关系。     

化合物结构／性质相关的研究／拓扑指数法（Ⅰ）

本文提出一种新的拓扑指数－ＥＡ系列指数，它是从表示分子图形的邻接矩阵出发，结合图形中顶点的度构造成ＥＡ矩阵，计算ＥＡ矩阵的本征值，求出本征值绝对值和指数ＥＡΣ及本征值绝对值最大值指数ＥＡｍａｘ，实验表明，ＥＡ系列指数具有良好的唯一性和相关性。     

The circular chemistry conceptual framework: A way forward to sustainability in industry 4.0

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Refractive index of water-AOT-n-heptane microemulsions

Refractive index measurements on water/AOT/n-heptane microemulsions as a function of the volume fraction of the dispersed phase (water plus AOT) and of the water/AOT molar ratio R have been performed at 25°C. The refractive index was found to vary monotonically with without any change in rate during the crossover of the percolation threshold. Such a behavior suggested that, well above the percolation threshold, the water-AOT-n-heptane microemulsions are still formed by water-containing AOT reversed micelles dispersed in the oil phase. The analysis of the experimental data allowed an evaluation the fraction of the water molecules bonded to the AOT head group as a function of R.