Hirshfeld surface analysis of two new phosphorothioic triamide structures

Hirshfeld surfaces and two‐dimensional fingerprint plots are used to analyse the intermolecular interactions in two new phosphorothioic triamide structures, namely N,N′,N′′‐tris(3,4‐dimethylphenyl)phosphorothioic triamide acetonitrile hemisolvate, P(S)[NHC₆H₃‐3,4‐(CH₃)₂]₃·0.5CH₃CN or C₂₄H₃₀N₃PS·0.5CH₃CN, (I), and N,N′,N′′‐tris(4‐methylphenyl)phosphorothioic triamide–3‐methylpiperidinium chloride (1/1), P(S)[NHC₆H₄(4‐CH₃)]₃·[3‐CH₃‐C₅H₉NH₂]⁺·Cl⁻ or C₂₁H₂₄N₃PS·C₆H₁₄N⁺·Cl⁻, (II). The asymmetric unit of (I) consists of two independent phosphorothioic triamide molecules and one acetonitrile solvent molecule, whereas for (II), the asymmetric unit is composed of three components (molecule, cation and anion). In the structure of (I), the different components are organized into a six‐molecule aggregate through N—H...S and N—H...N hydrogen bonds. The components of (II) are aggregated into a two‐dimensional array through N—H...S and N—H...Cl hydrogen bonds. Moreover, interesting features of packing arise in this structure due to the presence of a double hydrogen‐bond acceptor (the S atom of the phosphorothioic triamide molecule) and of a double hydrogen‐bond donor (the N—H unit of the cation). For both (I) and (II), the full fingerprint plot of each component is asymmetric as a consequence of the presence of three fragments. These analyses reveal that H...H interactions [67.7 and 64.3% for the two symmetry‐independent phosphorothioic triamide molecules of (I), 30.7% for the acetonitrile solvent of (I), 63.8% in the phosphorothioic triamide molecule of (II) and 62.9% in the 3‐methylpiperidinium cation of (II)] outnumber the other contacts for all the components in both structures, except for the chloride anion of (II), which only receives the Cl...H contact. The phosphorothioic triamide molecules of both structures include unsaturated C atoms, thus presenting C...H/H...C interactions: 17.6 and 21% for the two symmetry‐independent phosphorothioic triamide molecules in (I), and 22.7% for the phosphorothioic triamide molecule of (II). Furthermore, the N—H...S hydrogen bonds in both (I) and (II), and the N—H...Cl hydrogen bonds in (II), are the most prominent interactions, appearing as large red spots on the Hirshfeld surface maps. The N...H/H...N contacts in structure (I) are considerable, whereas for (II), they give a negligible contribution to the total interactions in the system.     

顶空气相色谱-质谱联用结合同位素峰形校正检索技术鉴别芝麻油风味成分

采用顶空气相色谱-质谱联用(GC-MS)仪结合同位素峰形校正检索技术鉴别了市售芝麻油风味成分中的71种化合物,占总检出化合物的90.2%。检出化合物可分为吡嗪、吡咯、吡啶、噻唑、噻吩、吲哚、唑、呋喃、醛类和酚类等,其中醛、酚、吡嗪和呋喃类化合物的含量较高,分别占风味成分含量的37.4%,20.1%,10.0%和6.7%。同位素峰形校正检索技术在低分辨率质谱上可对化合物的相对分子质量实现精确测量,从而为低分辨率四极杆质谱确定化合物的元素组成和解析化合物结构提供了重要依据,同时也为芝麻油的成分分析提供了新的技术手段。     

地方工科院校《功能高分子材料》课程教学内容的精选与实践

随着材料学的蓬勃发展,功能高分子材料的种类及用途日益繁多,因而《功能高分子材料》课程教学内容涵盖也不断延伸。针对地方工科院校高分子材料与工程专业人才培养的机制和目标,作者探索实践了如何以学生为本、以社会和行业的人才需求为导向,紧密联系地方经济与行业格局,因时因势对课程教学内容进行优化和完善。在此基础上,通过科学合理的教学实践,使学生既能牢固掌握功能高分子材料的基础知识,又能了解本领域最前沿的科学发展动态,拓宽学习思路,提高学习积极性,增强对专业的认可与对行业的期待。     

最近十年中国头发微量元素研究进展

2006—2015年,是中国头发微量元素研究继续取得重要成果的10年,也是该项研究量质转变的10年。概述了10年内中国头发微量元素研究的进展、现状和发展方向,高通量微量元素组学研究和微量微区分析技术的发展将引领头发微量元素研究领域走向新的高度。     

ZnO衍射花样180°不唯一性的消除

晶体电子衍射花样涉及到界面、位错等缺陷的晶体学性质测定时,需要设法消除180°不唯一性这一问题.应用Tecnai G~2 F20场发射透射电镜精密的倾斜样品台使晶体做有系统的倾转,观察衍射花样的变化并加以分析,从而消除了ZnO粉末单晶花样的180°不唯一性.     

Pattern‐avoiding permutations and Brownian excursion part I: Shapes and fluctuations

Permutations that avoid given patterns are among the most classical objects in combinatorics and have strong connections to many fields of mathematics, computer science and biology. In this paper we study the scaling limits of a random permutation avoiding a pattern of length 3 and their relations to Brownian excursion. Exploring this connection to Brownian excursion allows us to strengthen the recent results of Madras and Pehlivan [25] and Miner and Pak [29] as well as to understand many of the interesting phenomena that had previously gone unexplained. © 2016 Wiley Periodicals, Inc. Random Struct. Alg., 50, 394–419, 2017     

Flexible and powerful strategy for qualitative and quantitative analysis of valepotriates in Valeriana jatamansi Jones using high‐performance liquid chromatography with linear ion trap Orbitrap mass spectrometry

Valeriana jatamansi Jones is an important medicinal plant and its quality is closely related to its region of origin. In the current study, we utilized a flexible and powerful strategy for comprehensive evaluation of the quality diversity for 15 regions in China. The method was based on a hybrid linear ion trap‐Orbitrap mass spectrometry platform. For structure characterization, fragmentation patterns were detected by analyzing a series of standard compounds using data dependent multistage mass spectrometry acquisition. A fragment ion database for valepotriates was established, and the acquired data were high throughput filtered by fragment ion search for compound identification. For quantitative purposes, we normalized the mass spectrometry data of 15 samples using SIEVE 2.0 and the differences in composition were analyzed using principal component analysis combined with hierarchical clustering analysis. The results identified a total of 92 compounds from Valeriana jatamansi Jones. Samples from Dali, Kunming, and Baoshan have better qualities and concentrations of the main active constituents. To verify our strategy, we compared the valtrate, acevaltrate, and baldrinal contents using high‐performance liquid chromatography with diode array detector. We developed and validated a comprehensive qualitative and quantitative analytical method to achieve quality control of Valeriana jatamansi Jones.     

A novel tubular hydrogen‐bond pattern in a new diazaphosphole oxide: a combination of X‐ray crystallography and theoretical study of hydrogen bonds

In the structure of 2‐(4‐chloroanilino)‐1,3,2λ⁴‐diazaphosphol‐2‐one, C₁₂H₁₁ClN₃OP, each molecule is connected with four neighbouring molecules through (N—H)₂…O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R ³₃(12) and R ₄³(14) hydrogen‐bond ring motifs, combined with a C (4) chain motif. The hole constructed in the tubular architecture includes a 12‐atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co‐operating in classical hydrogen bonding, takes part in an N—H…π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen‐bond pattern. The energies of the N—H…O and N—H…π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen‐bonded cluster of molecules as the input file for the chemical calculations. In the ¹H NMR experiment, the nitrogen‐bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the ²J _H–P coupling constant.