C-H…O Hydrogen Bonds and π…π Interaction and the Crystal and Molecular Structures of 3-Nitro-benzylideneaniline-methyl-2’

The title compound (C14H12N2O2, Mr = 240.26) crystallizes in the monoclinic system, space group P21/a with a = 7.394(1), b = 21.334(3), c = 7.423(1) ? b = 89.82(1)? V = 1170.8(3) ?, Z = 4, Dc = 1.363 g/cm3, m(MoKa) = 0.93 cm-1 and F(000) = 504.00. The final R and wR are 0.0440 and 0.1370 for 2153 observed reflections (I > 2s(I)), respectively. The dihedral angle between the two phenyl rings is 52.9 and that between the NO2 group and its attached ring is 3.0. In the crystal, molecules are stacked along [100] through p…p interactions. The CH…O hydrogen bond (3.403 ? 120.4? laterally connects the stacks along [010] to form networks (001) which are further anti- parallelly connected by CH…O (3.382 ? 142.9) and p…p interactions extending along [001]. Also presented here is a brief study on the CH…O hydrogen bonds in nitro-substituted benzyl-ideneanilines which can be classified into five types, namely, )5(12R, )4(21R, )8(22R, )6(12R and )7(22R, with the first three occurring more often.

晶体中的C—H…O氢键

介绍了晶体中的Ｃ—Ｈ…Ｏ氢键，包括其键长、键角以及Ｃ—Ｈ基团的酸性与Ｏ原子的碱性对Ｃ—Ｈ…Ｏ键长的影响及Ｃ—Ｈ…Ｏ氢键在晶体工程学中的作用。

Synthesis, Spectroscopy and X-Ray Crystal Structure of 9-Methyl-3-Thiophen-2-Yl-Thieno [3, 2-e] [1, 2, 4] Triazolo [4, 3-c] Pyrimidine-8-Carboxylic Acid Ethyl Ester

The Preparation of 9-Methyl-3-thiophen-2-yl-thieno [3, 2-e] [1, 2, 4] triazolo [4, 3-c] pyrimi-dine-8-carboxylic acid ethyl ester is described. Elemental analysis, IR spectrum, 1H NMR, 13C NMR and X-ray crystal structure analyses were carried out to determine the composition and molecular structure of the title compound. There are two independent molecules in the asymmetric unit exhibiting intermolecular C-H…N, C-H…O interactions with additional π-π interaction that further helps in stabilizing the supramolecular structure. The results showed that the proposed method for synthesis is simple, precise and accurate which was further confirmed by crystal structure analysis.

Selective nickel-electrocatalyzed benzylic C-H oxygenation of functionalized alkyl arenes

Herein, a site-selective paired electrochemical C–H oxidation of functionalized alkyl arenes promoted by nickel catalyst is disclosed. A Ni(Ⅱ)-dioxygen species formed in situ efficiently enable the oxidation process under mild conditions with a broad substrate scope with excellent functional group compatibilities,such as free carboxylic acid, aldehyde, halogen(including aryl iodide), amide and amino acid. The use of the nickel catalyst in combination with water provides a safe, green and economical method for oxidation of a range of molecules varying in complexity and drug derivatives, demonstrating its potential application in organic synthesis and the pharmaceutical industry. Reaction outcomes and mechanistic studies revealed the key role of the in situ Ni(Ⅱ)-dioxygen species for the subsequent oxidation of C(sp^(3))–H bonds,and short-lived reactive intermediates(aryl radical cation) was rapidly captured by the combination of a bipolar ultramicroelectrode(BUME) with nano-electrospray ionization mass spectrometry.

HMX/DMF溶剂化物结构和分子间相互作用的理论研究(英文)

采用量子化学计算和分子动力学(MD)模拟,研究了溶剂化物环四亚甲基四硝胺(HMX)/N,N-二甲基甲酰胺(DMF)的结构和分子间相互作用。对浸渍在DMF溶剂中的β-HMX分子的MD模拟表明,HMX的分子构象已经从β转变为α相。在M P2/6-31G*水平上的理论计算也说明,在D M F溶剂中,α-HM X比β-HM X更稳定。这解释了在HM X/D M F溶剂化物的多晶型中,所有的HMX分子均呈α构象的原因。采用MP2/6-31G*方法,对α-HMX和DMF分子间可能的同型和异型二聚体进行结构优化。结果表明,组分间存在C—H…O氢键相互作用,并且α-HMX/DMF的稳定化能非常接近α-HMX/α-HMX,并远远大于D M F二聚体的。这意味着异型分子间力可和同型分子间力竞争。从热力学的观点来看,共结晶过程可能发生。对α-HM X在D M F中的过饱和溶液的M D模拟表明,分子间相互作用对共结晶有利。这些理论研究对理解在HM X的D M F溶液中为什么发生的是共结晶而不是重结晶提供了有价值的信息。

具有三维氢键网络结构的四溴对苯二甲酸铅一维配位聚合物的合成、表征与晶体结构(英文)

四溴对苯二甲酸(H2TBTA)与醋酸铅在DMF/H2O/CH3OH溶剂中通过分层扩散法组装得到一维配位聚合物{[Pb(TBTA)(DMF)2](DMF)2}n(1),利用元素分析、红外光谱及X-射线单晶衍射法对其进行了表征.化合物1属于单斜晶系,C2/c空间群,晶胞参数为a=1.623 1(4)nm,b=1.012 3(2)nm,c=2.029 0(6)nm,β=106.999(3)o,V=1.034 9 nm3,Z=4.在1的晶体结构中,每个八面体铅离子分别与来自2个TBTA的一对螯合羧基以及2个DMF分子上的6个氧原子配位,相邻的PbⅡ离子通过TBTA桥联形成一维配位链结构.晶体堆积分析结果表明,相邻配位链上的DMF配体之间存在C—H…O弱相互作用,将一维配位链拓展为三维超分子结构,且晶格DMF客体包结于此三维网络中.

Synthesis, Structure and Properties of Benzo[1,2-f:5,4-f＇]- diquinoline Derivatives： A Remarkably Strong Intramolecular C-H...O Hydrogen Bond

A series of benzo[1,2-f：5,4-f＇]diquinoline derivatives were synthesized starting from 2,7-diaminoanthracene, and their structures were determined by NMR, MS spectra and X-ray analysis. They showed a remarkably strong intramolecular C--H...O hydrogen bond, which resulted in an unexpected downfield chemical shift of the aromatic proton in CDCl3. Moreover, a significant fluorescent change of molecule lb in the presence of trifluoroacetic acid （TFA） was also observed.

Palladium-catalyzed R_2(O)P-directed C(sp^2)–H activation

In recent years,transition-metal-catalyzed inert C–H bond activation has developed rapidly and is a powerful protocol for the construction of new C–C or C–X bonds and the introduction of new functional groups.Our group has also developed a series of R2(O)P-directed Pd-catalyzed C–H functionalizations involving olefination,hydroxylation,acetoxylation,arylation,and acylation through an uncommon seven-membered cyclo-palladium pretransition state.Unlike previously used directing groups,the R2(O)P group acts as a directing group and is also involved in the construction of P,-hetero-ligands.