苝二酸酐与嘧啶衍生物的氢键组装

用半经验AM1方法对苝二酸酐与嘧啶衍生物的1:1及1:2氢键复合物进行理论研究,表明随着氢键数目增多,弱相互作用能变大,主体上的供电基和客体上的吸电基有利于氢键相互作用,氢键导致电子从主体流向客体.用INDO/SCI方法计算配合物的电子光谱,表明其长波吸收峰与主体相比发生兰移,各配合物的长波吸收峰位置相差不大,与实验一致.讨论吸收峰兰移的原因并对电子跃迁进行理论指认,同时得到了配合物的双质子转移势能曲线,给出了相对于N-H键的过渡态和活化能.     

变温过程中二甲基亚砜与水之间氢键行为的拉曼光谱研究

测量了在降温过程中体积比为1∶1的二甲基亚砜(DMSO)水溶液的拉曼光谱,并对DMSO水溶液的拉曼光谱进行了归属。对实验数据进行分析发现: 在降温过程中DMSO分子与水分子的分子间氢键、DMSO分子与DMSO分子和水分子与水分子间氢键的作用行为引起了DMSO的SO双键和水分子的O—H键的拉曼谱带的变化。进一步分析表明：在27～-30 ℃降温过程DMSO与水之间氢键加强,-30～-60 ℃降温过程水与水之间氢键代替DMSO与水之间的氢键。这为丰富水溶液的氢键理论提供了实验依据。     

含纳米棒银溶胶的制备及其光谱性质研究

以CTAB表面活性剂胶束为模板用化学还原法制备出含有银纳米棒的银胶体,用透射电镜(TEM)对颗 粒形貌进行了表征.UV Vis吸收谱显示,含银纳米棒溶胶有两个吸收蜂,其中长波长吸收峰位置随胶粒长径比增 加迅速红移和宽化.用多尺寸统计平均的Mie散射模型计算了纳米棒银胶体的吸收谱,较好地解释了长波长吸收 峰的宽化.以此胶体为衬底材料,测量了染料分子的表面增强拉曼散射(SERS),结果显示,SERS强度随胶体中 所含纳米棒长径比的增加呈现先显著增强后缓慢减弱的变化规律,用电磁增强理论对有关现象进行了分析.     

不同体系下氢键对聚丙烯酰胺光谱的影响

采用红外,紫外光谱分析不同体系下氢键对部分水解高分子聚丙烯酰胺光谱的影响。研究表明,高分子聚丙烯酰胺中的酰胺基与部分水解的羧酸基能形成分子内氢键导致酰胺基中游离-NH₂特征吸收峰向低频方向移动;聚丙烯酰胺在水溶液中随浓度的增大主要形成分子内氢键使最大吸收波长发生红移;在含中等浓度钠离子和钙离子的水溶液体系下,分子内氢键和分子间氢键同时存在,在含高浓度钠离子和钙离子体系下,则主要形成分子间氢键。不同体系下,氢键对聚丙烯酰胺光谱的影响不同：在水溶液体系下,其最大吸收波长红移8 nm,在钠离子单独存在的体系下,最大吸收波长红移4 nm,在钙离子和钠离子同时存在的体系下,最大吸收波长红移2 nm。     

Some Aspects of Intra- and Inter-Molecular Reactions of Siliconium Ions in the Vapor Phase

Intramolecular rearrangement processes in the mass spectra of trimethylsilyl derivatives of hydroxy steroids are discussed in terms of the reaction of a siliconium center and a heteroatom. The reaction is shown to be stereospecific. The reactivity of siliconium cations also results in the occurrence of intermolecular reactions under electron impact ionization conditions. Tetramethylsilane is used as a precursor for the production of siliconium ions and examples of chemical ionization mass spectra employing this reagent are shown.     

嵌段聚酯型聚脲氨酯硬段微区中氢键化的红外光谱研究

用红外光谱法对基于4,4′二苯基甲烷二异氰酸酯（MDI）、乙二胺（ED）和聚己二酸丁二醇酯（PBA）（分子量分别为1975和1228）的两系列嵌段聚酯型聚脲氨酯（PUU）硬段微区的氢键化进行了研究。发出脲C＝0基随着硬段含量增国出现双峰吸收,提出了PUU不同长度硬段序列中脲C＝0基的两种平面氢键化的模型。认为这些平面氢键可以通过进一步键合来形成硬段微区中的三维氢键。     

2,2,6,6-四甲基哌啶氮氧自由基与卤仿形成卤键或氢键的理论研究

利用理论计算化学研究了2,2,6,6-四甲基哌啶-N-氧自由基与卤仿形成卤键和氢键络合物的可能性. 从分子静电势、络合物分子的结构参数、络合物的作用能以及自然键轨道理论的角度着手研究. 结果表明,卤键与氢键络合物的键合能均遵循氯化物<溴化物<碘化物,氢键络合物作用强度大于相应的卤键络合物. 因此,卤仿与2,2,6,6-四甲基哌啶-N-氧自由基之间作用模式氢键为主. 需要注意的是,碘仿形成卤键的作用强度与氢键相当,因此在碘仿中,卤键与氢键两种模式应该竞争性的存在.     

受限于对称性破缺狭缝间氢键流体的相平衡研究

利用密度泛函理论并结合改进的基本度量理论研究了受限于对称性破缺狭缝间氢键流体的相平衡. 首先根据氢键流体的吸附-脱附等温线及相应巨势获得不同条件下氢键流体的相图. 进一步讨论了氢键作用、狭缝间距、狭缝与流体分子间相互作用及对称性破缺程度等因素对氢键流体相平衡的影响. 结果表明, 由于狭缝与流体分子及流体分子间的相互作用存在竞争, 使得受限于对称性破缺条件下的氢键流体呈现更为复杂的相态特征.     

花二酸酐与嘧啶衍生物的氢键组装(英文)

用半经验AM1方法对苝二酸酐与嘧啶衍生物的1∶1及1∶2氢键复合物进行理论研究,表明随着氢键数目增多,弱相互作用能变大,主体上的供电基和客体上的吸电基有利于氢键相互作用,氢键导致电子从主体流向客体。用INDO／SCI方法计算配合物的电子光谱,表明其长波吸收峰与主体相比发生兰移,各配合物的长波吸收峰位置相差不大,与实验一致。讨论吸收峰兰移的原因并对电子跃迁进行理论指认,同时得到了配合物的双质子转移势能曲线,给出了相对于N-H键的过渡态和活化能。     

Near-Infrared Study of the Hydrogen Bonding in Acetone-Methanol and Acetone-Ethanol Mixtures: Roles of Mechanical and Electrical Anharmonicities of Hydroxyl Oscillator

Near-infrared spectra of methanol-acetone and ethanol-acetone mixtures in the entire mole fraction range in increments of 0.1 were recorded in the region of 7500–6000 cm^?1. The first overtone bands of the hydroxyl (OH) groups were assigned to the polymeric and oligomeric OH associations. In both solutions, the frequency of the polymeric OH band decreased with the increase in the mole fraction of alcohol, which indicated the increase in the hydrogen bonding strength. The integrated area of the polymeric OH band followed the opposite trend to the frequency with the mole fraction. The nonlinearity of the plot of the integrated band area of the polymeric OH band of methanol versus the mole fraction of acetone revealed the nonideal character of the methanol-acetone mixtures, whereas the opposite was observed for the ethanol-acetone mixtures. These observations have been explained in terms of mechanical and electrical anharmonicities of the OH oscillator.     

Hydrogen Bonding Between Substituted Phenols and CH3COOCH3 or CH2CICOOCH3: An FTIR Spectroscopic Study

The hydrogen bonded complexes between phenol derivatives and methyl acetate and methyl chloroacetate were studied in carbon tetrachloride solution by FTIR spectroscopy. Temperature variation studies were used to evaluate both formation constants and the enthalpies of complex formation. It is shown that the relative values of enthalpies associated with the hydrogen bonding process in the various studied systems depend mainly on the electron releasing ability of the phenol substituents as well as on the polarization state of the carbonyl bond of the ester. In addition, it is also shown that the observed shifts in the carbonyl stretching frequency upon complexation can be correlated with ΔH, thus providing a useful indirect way of measuring the strength of the hydrogen bond.     

IR Spectroscopic Evidence of Hydrogen Bonding in Piperidine

Abstract

The IR spectra of piperidine dissolved in n-heptane revealed that a self-association equilibrium via weak hydrogen bonds exists in this system. The dimerisation constant was found to be 0.35 1·mol^?1 at 29°. No higher associates than dimers were found.     

Vibrational Spectra of and Isotope Effect in Hydrogen Bonded Potassium Hydrogen Oxalate

The crystal structure of potassium hydrogen oxalate, KHC₂O₄, has been determined by Pedersen¹. There are infinite chains of hydrogen oxalate ions held together by short (2. 534 Å) hydrogen bonds. The O-D‥O distance of KDC₂O₄ derived from lattice constant changes is estimated to be about 0.005 Å larger than the O-H‥O distance which means that the isotope effect is small¹. We believe, however, on the ground of the infrared and Raman spectra of KHC₂O₄ and KDC₂O₄ repotted in this paper, that the isotope effect in these crystals is much larger.     

Hydrogen Bonding and the NMR Parameters in Dimethylformamide

The oxygen atom of dimethylformamide (DMF) is a good electron doaor site and in a proton donor solvent the solute-solvent interactions would include hydrogen bonding at this site. As this hydrogen bonding is expected to be relatively strong, it would predominate when both the lMF and the protonic acid are present at very low concentration in a solvent such as carbon tetrachloride, and the effect of this hydrogen bonding on the proton chemical shifts and coupling constants i n LMF can be observed. If the protonic acid is aromatic, such as phenol, and is in excess of the LMF, other form(s) of solut-olvent association would become significant and give rise to aromatic solvent induced shifts (ASIS), which would obscure the effect of hydrogen bonding at the oxygen site of the MF. The ASIS in DMF are well known, and the shifts have been attributed to the diamagnetic ring current effect of the aromatic solvent and specificsolut-olvent association.¹ More recently, the ASIS has been interpreted as the result of time-averaged general solvation around the polar site of the solute.²     

三种二元水溶液体系中氢键对拉曼线宽的影响

采用显微共聚焦拉曼光谱对三种二元水溶液(乙腈/水、二甲基亚砜(DMSO)/水和丙酮/水)进行测量,得到含有氢键作用的水溶液体系拉曼频移和线宽随浓度的变化规律。应用混合模型和相互作用体系的线宽经验公式对实验结果进行了分析。结果表明,含有氢键作用的水溶液体系中,氢键作用越强线宽越大,并且线宽随单位浓度变化率大;同种氢键体系中,线宽不仅受浓度浮动的影响,氢键作用也是一个重要的影响因素,定量分析证明线宽与浓度、氢键作用关系很好地符合Ojha等提出的线宽公式。     

甲醇的高压拉曼光谱研究

研究了甲醇在温度301K、压力169．2～713．8MPa下的拉曼特征。其中νCH区伸缩振动随压力增大，拉曼位移向高频方向移动，说明C-H键键能在增大；而νOH区伸缩振动随压力增大，拉曼位移则向低频方向移动，表明氢键对O-H基团的影响大于压力效应。另外，O-H伸缩振动峰的相对面积随压力的增大而减小，说明对C-H键而言，O-H键总强度是减弱的。     

N.M.R. Spectral Studies of Some Quinolone Derivatives. Part II.1 Further Studies of the Effect of Substitution on the Degree of Hydrogen Bonding

The chemical shift of the NH proton for a series of 4-quinolone derivatives has been studied. It is proposed that the inhibition of π-hydrogen bonding is a dominant factor which contributes to the observed NH chemical shift. Details of the ¹H n.m.r. spectra of some 2- and 4- quinolone derivatives are presented.     

氮气水合物储氢的激光拉曼光谱研究

近年来,笼型水合物储氢已成为储氢研究的热点之一。采用激光拉曼光谱开展了以氮气水合物为载体的储氢实验研究。在较为温和的条件下(15 MPa, -18 ℃),使合成的氮气水合物与氢气发生反应,对反应产物的拉曼光谱分析结果显示,氢气分子进入到水合物的笼型结构中,并且呈现出多分子的笼占有状态;氮气水合物与氢气的反应时间是影响储氢效果的重要因素。研究结果表明,氮气水合物有希望成为一种有效的储氢介质。     

二甲基亚砜水溶液表面张力及粘度与氢键的拉曼光谱研究

利用ZL-10型全自动界面张力仪(柏金环法)和NDJ-5S型数显粘度计测量体积分数为5%～100%的二甲基亚砜(DMSO)水溶液及超纯水,得到表面张力和粘度的变化规律。用拉曼光谱仪测量不同浓度DMSO水溶液的拉曼光谱,得到体系中含氢键作用的拉曼频移变化规律。实验结果表明,DMSO水溶液的表面张力随浓度的变化受DMSO水溶液中氢键作用的影响,且与氢键强度成反相关。DMSO与水的氢键作用对粘度的影响较表面张力更为复杂,粘度随浓度的变化呈二次函数的反常现象,影响因素包含氢键强度,氢键网络结构和空间方向性多个方面。该研究探索一种利用拉曼光谱研究水溶液微观结构与宏观物理性质关系的实验方法。     

3-羟基黄酮在不同极性和酸碱度溶剂中的光谱研究

实验观测了3-羟基黄酮(3-HF)在不同极性溶剂中的吸收光谱和荧光光谱,发现在吸收光谱中有3个吸收带,峰值位于300和345 nm的两个吸收带较强,位于415 nm处的吸收带较弱。用345 nm作为激发光,观测到两个荧光带,其中峰值位于400 nm的荧光带为3-HF稀醇式构型的发射,随着溶剂极性的增大其强度增强,峰值位于526 nm的荧光带为3-HF互变异构体的发射,随着溶剂极性的增大其强度减弱,这表明溶剂极性阻碍质子转移的发生。用415 nm的光激发样品,在荧光光谱中发现了3个新荧光谱带,峰值分别位于440,471和515 nm,这3个荧光谱带归属至今未见报道。为了指认这3个荧光谱带,分别观测了3-HF在不同酸碱度溶液的荧光光谱及其吸收光谱,通过对这些光谱的分析研究,指认出荧光峰位于440和471 nm的荧光谱带为3-HF的两种阳离子的发射,峰值位于515 nm的荧光谱带为3-HF的阴离子的发射。