Intermolecular Hydrogen Bonding between Water and Pyrazine

Completely planar is the hydrogen-bonded complex of pyrazine and water (see sketch), which was obtained by supersonic expansion and investigated by rotational spectroscopy. The water molecule lies in the plane of the aromatic ring, and the lone pair of electrons on the nitrogen atom functions as the acceptor in the N⋅⋅⋅H–O hydrogen bond, not—as in the corresponding benzene complex—the π electrons.     

Direct Evidence for the Effect of Intermolecular Hydrogen Bonding on Organogels

In order to get direct evidence for the effect of intermolecular hydrogen bonding on the organogels, one arnide group in N-（3, 4, 5-octyloxybenzoyl）-N＇-（4＇-aminobenzoyl）hydrazine（D8） was replaced by a Schiff base group, forming N-（3,4,5-octyloxybenzoyl）-N＇-（4＇-amidobenzoyl） acylhydrazone（T8SchA）. D8 and T8SchA organogels in cyclohexane show the same hexagonal columnar structure. And the hydrogen bonding was demonstrated to be still interacting in the organogels. However, although the molecular geometry of D8 was well retained in T8SchA, the molecular dipole moment of T8SchA is bigger than that of D8 due to the reduction of the number of hydrogen bonds. Thus, the decreased gelling stability of T8SchA compared to that of D8 can only be attributed to the reduction of the number of intermolecular hydrogen bonds, which provides direct evidence that intermolecular hydrogen bonding plays an important role in stabilising organogels.     

烟酰胺合铜固体化合物中的分子间氢键

合成了三个烟酰胺配位的铜(Ⅱ)化合物[Cu(nia)₂(H₂O)₄](bpds) 1,[Cu(nia)₂(H₂O)₄](2,6-nds)·2H₂O 2 和[Cu(nia)₂ (H₂O)₄][Cu(nia)₂(H₂O)₂(1,5-nds)2]·4H₂O 3(nia=烟酰胺,bpds=4,4′-联苯二磺酸,nds=萘二磺酸),并通过X-射线单晶衍射确定了其晶体结构。化合物1～3中的配合阳离子都是四个水和两个烟酰胺配位的铜(Ⅱ)离子,八面体CuO₄N₂具有不同程度的畸变。在化合物3中,阴离子是由Cu(Ⅱ)与两个水、两个烟酰胺和两个磺酸形成的配离子。在1和2中,配合阳离子间由酰胺以头对头的氢键模式相互连结成一维带状结构,再分别通过吡啶环上的C-H与酰胺N或配位水所形成的氢键扩展成二维结构。在3中,配合阳离子间通过配位水和烟酰胺间的氢键连结成一维锯齿状结构。这三个化合物的配合阳离子构成相同,不同的阴离子导致了阳离子间不同模式氢键的形成。     

Enhanced Room-Temperature Phosphorescence through Intermolecular Halogen/Hydrogen Bonding

Room-temperature phosphorescence (RTP) materials with high efficiency have attracted much attention because they have unique characteristics that cannot be realized in conventional fluorescent materials. Unfortunately, efficient RTP in metal-free organic materials is very rare and it has traditionally been considered as the feature to divide purely organic compounds from organometallic and inorganic compounds. There has been increasing research interest in the design and preparation of metal-free organic RTP materials in recent years. It has been reported that intermolecular interactions make a big difference to the photophysical behavior of organic molecules. In this regard, herein, the parameters that affect RTP efficiency are discussed, and a brief review of recent intermolecular halogen-/hydrogen-bonding strategies for efficient RTP in metal-free organic materials are provided. The opportunities and challenges are finally elaborated in the hope of guiding promising directions for the design and application of RTP materials.     

Thermotropic Liquid Crystals Formed by Intermolecular Hydrogen Bonding Interactions

The role of hydrogen bonding in the formation or stabilization of liquid crystalline phases has only recently been appreciated. Following the first, wellestablished examples of liquid crystal formation from the dimerization of aromatic carboxylic acids, through hydrogen bonding, several classes of compounds have recently been synthesized, the liquid crystalline behavior of which is also dependent on intermolecular hydrogen bonds between similar or dissimilar molecules. In this review the main classes of compounds exhibiting liquid crystallinity due to hydrogen bonding are presented to show the diversity of organic compounds that can be used as building elements in liquid crystals. The molecules are either of the rigid-rod anisotropic or amphiphilic types such as molecules appropriately functionalized with pyridyl and carboxyl groups, whose interaction leads to the formation of liquid crystals; amphiphilic carbohydrates and amphiphilic and bolaamphiphilic compounds with multiple hydroxyl groups whose dimerization or association is indispensable for the formation of liquid crystals; and certain amphiphilic carboxylic acids with monomeric or polymeric mesogens and amphiphilic-type compounds bearing different moieties, whose interaction may lead to the formation of mesomorphic compounds. Associated with the macroscopic display of liquid crystalline phases is the supramolecular structure, and therefore rather extended discussion of these structures are included in this review.     

基于氢键的自组装超分子体系

氢键自组装超分子是超分子体系中相对较新颖和引人注意的领域,它在化学和生物体系中占据非常重要的位置。本文主要介绍目前文献报道的一系列由不同氢键缔合方式形成的自组装超分子。     

基于氢键的自组装超分子体系

氢键自组装超分子是超分子体系中相对较新颖和引入注意的领域，它在化学和生物体系中占据非常重要的位置。本文主要介绍目前文献报道的一系列由不同氢键缔合方式形成的自组装超分子。     

山梨醇改性聚乙烯醇体系的氢键作用及对水状态的影响

采用二维相关红外光谱研究了水渗透进入聚乙烯醇(PVA)及其改性基体过程中, 体系的氢键作用及对水状态的影响; 通过差示扫描量热分析(DSC)研究了改性剂山梨醇(S)对改性PVA中水状态的影响. 实验结果表明, S能通过其羟基与水形成较强氢键, 从而显著改变体系中水的状态及其蒸发行为, 使体系自由水含量逐渐减少, 水的蒸发峰温度升高.     

Synthesis of a New Self-Assembly Liquid Crystalline Polymer Through Intermolecular Hydrogen Bonding

A new side chain liquid crystalline polymer with biphenyl mesogenic group has been prepared. This polymer forms a bilayer smectic A phase through intermolecular hydrogen bonding according to the result of X-ray diffraction. Its phase transition was studied lining DSC and polarized optical microscopy. Infrared spectroscopic measurements show that cyclic dimeric hydrogen bonds of carboxylic acids are embedded in the bilayer.     

P（MMA—MAA）／PEO氢键复合物的增容效应

本文研究了P(MMA-MAA)/PEO氢键复合物对一些聚合物共混体系的增容效应。首次用机械共混方法制备了P(MMA-MAA)/PEO氢键复合物。该复合物不能被甲醇革取,其热失重行为不是其组分聚合物的加和,表明此复合物不是简单的共混物。实验结果证实,该复合物可以改进PMMA/PEO体系的相容性,改善PVC共混体系的力学性能和加工性能。     

乙二醇的分子间氢键结构动力学的飞秒非线性红外光谱

利用稳态线性红外光谱和飞秒泵浦-探测红外光谱技术, 研究了在乙腈(MeCN)、丙酮(AC)、四氢呋喃(THF)和二甲基亚砜(DMSO)溶剂中乙二醇(EG)的结构和羟基(―OH)伸缩振动动力学. 结果表明, 乙二醇的―OH伸缩振动的频率位置、峰宽以及振动弛豫动力学都表现出强烈的溶剂依赖性. 乙二醇溶液中至少存在两种形式的分子间氢键, 一种是溶质-溶剂团簇的分子间氢键, 另一种是溶质-溶质团簇的分子间氢键. 量子化学计算预测的―OH伸缩振动频率的溶剂依赖性与我们的红外光谱实验观测结果一致. 进一步, 我们发现在乙腈中参与形成溶质-溶剂团簇氢键的乙二醇―OH伸缩振动具有最慢的弛豫动力学, 丙酮和四氢呋喃次之, 而最快的弛豫动力学过程发生在二甲基亚砜中. 在每一溶剂条件下, 乙二醇/乙二醇溶质团簇中―OH伸缩振动弛豫都更快一些. 本文结果有助于认识在溶质-溶质、溶质-溶剂分子团簇共存的体系中不同分子间氢键的结构动力学特性.     

Recognition of Guanine by a Designed Triazine-based Fluorescent Probe through Intermolecular Multiple Hydrogen Bonding

A new fluorescent probe with a long-wavelength emission and multiple hydrogen bond sites for guanine, 3-(4-chloro-6-p-nitrophenoxy-1,3,5-triazinylamino)-7-dimethylamino-2-methylphenazine (CNTDP), was designed and synthesized by using cyanuric chloride as a molecular scaffold, neutral red as a fluorophore and p-nitrophenol as an assistant unit. The recognition behavior of CNTDP for guanine and its spectroscopic properties in different solvents were investigated. It was found that the probe's fluorescence can be selectively quenched by guanine instead of thymine, indicating that fully complementary hydrogen bonding plays a key role in such a recognition process. In addition, the fluorescence quenching mechanism of the probe by guanine and the electronic effects of neutral red, triazine ring and p-nitrophenol moieties on the fluorescence of the whole molecule were also discussed.     

α-Ketoacid Intermolecular Hydrogen Bonding. Supramolecular Ribbons and Stacking in α-Pyrroleglyoxylic Acids

Summary.  Rarely-seen carboxylic acid to ketone intermolecular hydrogen bonding is found in crystal structures of α-pyrroleglyoxylic acids. 3,4-Diethyl-1H-pyrrole-2-glyoxylic acid, prepared by saponfication of the reaction product between 3,4-diethylpyrrole and ethyl oxalyl chloride formed crystals that showed the uncommon carboxyl to ketone intermolecular hydrogen bonding, with the hydrogen-bonded α-pyrroleglyoxylic acids stacked neatly in layers. This α-ketoacid hydrogen-bonding pattern was repeated in (Z)-2,3,7,8-tetraethyl-10H-dipyrrin-1-one-9-glyoxylic acid, which also engaged in dipyrrinone-to-dipyrrinone intermolecular hydrogen bonding to form supramolecular ribbons in the crystal.     

α-Ketoacid Intermolecular Hydrogen Bonding. Supramolecular Ribbons and Stacking in α-Pyrroleglyoxylic Acids

Rarely-seen carboxylic acid to ketone intermolecular hydrogen bonding is found in crystal structures of α-pyrroleglyoxylic acids. 3,4-Diethyl-1H-pyrrole-2-glyoxylic acid, prepared by saponfication of the reaction product between 3,4-diethylpyrrole and ethyl oxalyl chloride formed crystals that showed the uncommon carboxyl to ketone intermolecular hydrogen bonding, with the hydrogen-bonded α-pyrroleglyoxylic acids stacked neatly in layers. This α-ketoacid hydrogen-bonding pattern was repeated in (Z)-2,3,7,8-tetraethyl-10H-dipyrrin-1-one-9-glyoxylic acid, which also engaged in dipyrrinone-to-dipyrrinone intermolecular hydrogen bonding to form supramolecular ribbons in the crystal.     

Co-existing Intermolecular Halogen Bonding and Hydrogen Bonding in the Compound Trans-5,10-bis（1-bromodifluoro-acetyl-1-ethoxycarbonyl-methylidene）thianthrene

Trans-5,10-bis(1-bromodifluoroacetyl-l-ethoxycarbonyl-methylidene)thianthrene (1b) was prepared from the reaction of BrCF2COC(N2)CO2Et with thianthrene. X-ray single crystal diffraction analysis showed that the intermolecular halogen bonding and hydrogen bonding coexisted in this compound. The bromine atom acted as an electron acceptor in the halogen bond and an electron donor in the hydrogen bond. It is the first example that the bromine atom acted as such a dual role in the hydrogen and halogen bond.     

N-甲基苯胺、二苯胺与质子受体相互作用的研究

测量了N-甲基苯胺、二苯胺与一些极性非质子溶剂（B）在CCl_4中的红外光谱，观察到这两种劳胺均与所研究的质子受体发生了氢键交叉缔合作用，并利用光谱数据计算了相应缔合物的形成常数和部分氢键能．结果表明，二苯胺是比N-甲基苯胺更强的质子供体，非质子溶剂的极性、空间效应和不同成键原子对交叉缔合物的稳定性均有一定的影响．还从分子结构对有关结果进行了讨论.     

用平均场理论研究盘状液晶分子间氢键对清亮点的影响

我们前期的合成和实验发现, 对于一系列含酰胺基支链的苯并菲分子, 其生成的液晶的清亮点的高低与分子间氢键的数目有关. 采用Gay-Berne势模拟液晶分子的双体势, 用量子化学和分子力学相结合的ONIOM (HF/STO-3G: UFF)方法优化含酰胺基支链的苯并菲分子的单体和双体的构型和能量, 从而获得Gay-Berne势的参数. 在此基础上, 根据平均场理论, 解一个关于序参量和温度的积分方程, 求出液晶的清亮点. 计算结果与实验一致, 可以解释清亮点和分子间氢键的关系.     

The Effect of Hydrogen Bonding on Intramolecular Chain Transfer in Polymerization of Acrylates

Propagation rate coefficients (k_p) for 2‐hydroxyethyl acrylate (HEA) have been determined by pulsed‐laser polymerization (PLP) combined with size‐exclusion chromatography (SEC) between 20 and 60 °C using pulse repetition rates of 50 and 100 Hz. The success of PLP–SEC under these conditions suggests that HEA is not subjected to the intramolecular chain transfer to polymer (backbiting) reactions dominant for other acrylates; ¹³C NMR analysis shows that the quaternary carbon observed in PLP‐generated poly(butyl acrylate) (pBA) samples is not observed in pHEA. These results are related to H‐bonding in the system, as it is shown that the introduction of H‐bonding by addition of n‐butanol to BA suppresses backbiting, and the disruption of H‐bonding by addition of dimethylformamide to HEA leads to an increased level of backbiting.