阶梯式循环冲击下煤中氢键红外光谱变化规律（英文）

煤结构中存在的大量氢键对其化学结构和性质具有重要影响。为了研究煤在冲击破坏过程中氢键的变化。设计落锤循环冲击系统,实现对煤样的循环定量冲击。利用红外光谱仪进行光谱分析。研究得出东庞1/3焦煤主要的氢键类型是free OH groups,OH…π,OH…OH,cyclic OH tetramers和OH…N以及它们随冲击破坏的变化规律。在冲击力的作用下,煤体分子间氢键吸收强度变化非常明显,自由羟基也在冲击作用下发生机械力化学反应。对红外光谱进行高斯函数拟合分峰,发现各类氢键吸收强度随着冲能量的增加而减小,但其趋势在放缓。统计两者关系,得到各类氢键的光谱吸收强度与冲击能量的拟合方程,两者符合幂函数关系。对比拟合方程的幂指数,得出氢键在受冲击破坏时发生变化的敏感性顺序:free OH groups>cyclic OH tetramers>OH…N>OH…π>OH…OH。     

基于微流控芯片的电解质溶液太赫兹吸收特性研究

由于许多生物分子的振动和转动能级均在太赫兹波段,且太赫兹波具有电子能量低（约4 meV）,不会破坏待测样品的特性,因此可以采用太赫兹光谱技术检测生物样品。然而许多生物分子在液体环境中才能保持其生物活性,需要在盐溶液中来探究酸碱环境对其的影响,以及在盐类缓冲液中研究其生物特性。但水作为极性液体对太赫兹波有强烈的吸收,因此,探究如何减少水对太赫兹吸收的方法非常必要。水对太赫兹的吸收主要因水分子间氢键造成,现阶段最常见的方法是减少水与太赫兹波的作用距离以及破坏水分子间的氢键。利用夹心式微流控芯片在太赫兹时域光谱系统下通过观察光谱强度变化来探究电解质对水分子间氢键的影响,既减少了水和太赫兹波的作用距离,又探究了电解质对水分子间氢键的作用。在微流控芯片中分别加入不同种类以及不同浓度的电解质,通过观察其在0.1～1.0 THz范围内的光谱强度变化来分析不同电解质对水分子间氢键的影响。部分电解质促进氢键的缔合,而另一部分则破坏氢键的形成,在太赫兹光谱范围内表现为光谱强度的变化。若促进氢键的缔合则对太赫兹吸收变大,光谱强度减弱;若破坏氢键的缔合则对太赫兹吸收减弱,光谱强度增加。研究结果发现：在水中加入KCl和KBr时,太赫兹光谱强度增加,表明二者对氢键有破坏作用,使得光谱强度变大;然而当加入MgCl₂和CaCl₂时,太赫兹光谱强度减弱,表明二者对氢键有缔合作用,从而使光谱强度变小。利用太赫兹技术在0.1～1.0 THz范围内研究KCl,KBr,MgCl₂和CaCl₂这四种不同浓度的电解质溶液特性,发现它们只会对光谱强度造成一定影响,不会引入新的特征吸收峰以及对待测样品造成干扰。这对于研究诸如大肠杆菌、枯草芽孢杆菌等在0.1～1.0 THz范围内有特征吸收谱的生物分子具有一定的实用价值。在溶液中加入所需的电解质并借助微流控芯片不仅可以识别待测样品、研究待测样品的光谱信息、探究其生物特性,而且为进一步推动太赫兹技术在生化方面的应用研究提供了先决条件。     

质子化水团簇对乙炔溶剂化作用的结构与红外光谱

利用团簇模型研究了质子化水团簇对乙炔的溶剂化作用. H⁺(C₂H₂)(H₂O)_n (n=1~5)的量子化学计算结果表明,水分子倾向与乙炔的π电子形成新型OH…π氢键作用,并且乙炔的第一溶剂层需要4个水分子来完成. 模拟的红外光谱揭示了OH…π氢键作用后的OH伸缩振动是研究乙炔与水溶剂化过程的灵敏探针. 这些红外光谱可以用红外光解离光谱实验方法测得,将为理解OH…π氢键作用以及质子化水团簇如何溶剂化乙炔提供有力的科学数据.     

苏丹红系列染料在有机溶液中的紫外-可见光谱研究

研究了苏丹红Ⅰ、苏丹红Ⅲ和苏丹红Ⅳ在非极性溶剂石油醚和极性溶剂乙腈及乙腈-水混合溶液中的紫外-可见光谱特征。在极性溶剂中苏丹红系列的可见区特征吸收峰比在非极性溶液中略有红移;在乙腈-水混合溶液中,苏丹红Ⅰ的特征吸收峰比在乙腈溶剂中红移,最大红移达13 nm,吸收强度最大增幅为34.5%;苏丹红Ⅲ的特征吸收峰红移8 nm,吸收强度增幅为11%;苏丹红Ⅳ的特征吸收峰先红移后蓝移,吸收强度增幅数仅为2.5%。造成这一变化的原因是在乙腈-水混合溶液中,苏丹红Ⅰ, Ⅲ, Ⅳ分子内氢键被破坏,扩大了π键离域范围所致。     

ATR-IR分析氢氧化钠对水及离子液体/水体系氢键作用的影响

利用衰减全反射红外光谱（ATR-IR）分析NaOH对水及1-乙基-3-甲基咪唑醋酸酯离子液体水溶液（EmimAc/水）氢键网络的影响,研究结果表明,NaOH的加入会影响水分子的氢键对称性和类型,对称性氢键谱带Ⅰ（3 218 cm-1）和Ⅱ（3 375 cm-1）随着NaOH浓度的提高而降低。NaOH使水溶液氢键发生极化,产生连续吸收带,连续吸收带随着NaOH浓度的提高而增强。水对EmimAc的阳离子和阴离子均有影响。水分子的OH和EmimAc的COO-产生强的相互作用,在3 400~3 200 cm-1产生宽的吸收谱带;而水分子的质子和COO-作用使得C═O吸收谱带红移。水的加入使得EmimAc指纹区的谱带蓝移或吸收强度下降,表明水可以破坏EmimAc原有的氢键网络,形成“阴离子…HOH…阴离子”团簇,减弱了离子液体阴、阳离子之间的相互作用。NaOH替代水与EmimAc混合,ATR-IR谱图的变化并不显著,主要表现在谱带的吸收强度上。与EmimAc/水相比,EmimAc/NaOH水溶液的ATR-IR谱的吸收强度更高,表明NaOH水溶液对EmimAc氢键网络的破坏不如水显著。由此可见,可利用EmimAc/NaOH体系降低离子液体体系黏度,并且降低离子液体使用成本,对木质纤维原料预处理有一定的指导意义。     

氟羟磷灰石通道离子的FTIR研究

以傅立叶变换红外光谱为表征手段,对合成的氟羟磷灰石通道离子进行研究。结果发现:F-离子替换羟基后,羟基在3573和634 cm-1的振动吸收带强度减弱,而在3542、678、715和736 cm-1左右出现新的振动谱带,且随F-离子含量不同出现规律性变化。新出现的谱带数目与群论推测的结果相符,表明该谱带属于羟基基团;羟基振动吸收带的变化,表明F-离子替换羟基的位置,形成[OH…F]氢键,使羟基的伸缩振动向低频偏移,弯曲振动向高频偏移。另外,通过3542-3573cm-1和715-736cm-1左右的谱带相对面积比与F-含量的关系,可为F-离子替换羟基行为提供一些依据。     

发光二极管归一化光谱模型的修正

受自吸收等因素的影响,由发光二极管(LED)归一化光谱模型得到的光谱与实测LED光谱之间存在差异。为得到与实测LED光谱相吻合的归一化光谱模型,将由归一化光谱模型得到的理论光谱与实测光谱相减得到近似的自吸收谱。通过分析自吸收谱的峰值强度和半峰全宽与温度之间的关系以及其峰值能量与实测光谱峰值能量之间的定量关系,结合LED光谱的高斯模型和归一化光谱模型给出了自吸收谱的拟合表达式,并作为归一化光谱模型的修正项,对归一化光谱模型进行修正。在不同测试温度下的实验结果表明修正后的平均模型误差小于4%,证明由修正后的归一化光谱模型得到的光谱与实测光谱相吻合。     

利用光谱吸收深度定量反演碳酸盐矿物的影响因素及应用分析

光谱吸收特征是矿物识别与定量反演的重要指标。为提高利用光谱吸收特征定量反演矿物精度,以方解石为代表,以线性混合光谱模型与连续统去除方法为基础,以连续统去除吸收深度(CRBD)为分析对象,按端元光谱在2.33 μm附近有无吸收特征对光谱进行分类,并分析每类数据与方解石混合光谱CRBD随丰度、反射率以及光谱特征等影响因素的变化规律,进而非线性拟合其变化范围并提出一种新的矿物含量表示方法。研究结果表明,端元丰度对CRBD值影响较大,方解石丰度越大,吸收特征越明显,CRBD值越大。同样,混合端元反射率与光谱特征对混合光谱CRBD值影响也较明显,当混合端元光谱在2.33 μm附近为无特征时,端元光谱反射率越小,CRBD随碳酸盐丰度变化上凸越明显,为反射峰特征时,端元光谱反射率越大,下凹越明显;混合端元在2.33 μm附近为吸收谷特征时,CRBD随碳酸盐丰度接近线性变化。通过交叉分析与多端元混合光谱CRBD变化分析发现,混合光谱CRBD随碳酸盐矿物丰度及混合端元反射率变化受限于一定范围,其上限拟合方程满足指数函数变化,下限拟合方程为三次多项式函数,且拟合精度较高,R2均高于0.99,RMSE低于0.005。为实现矿物含量的精确预测,根据拟合方程提出一种以变化范围替代定量值来表示碳酸盐矿物丰度分布的方法,实现碳酸盐矿物含量反演的范围表示。通过影响因素分析及范围表示法可为矿产监测、定量评估等提供新的表达方法,为建立具有普适性的地物定量反演模型提供理论参考。     

制备腈菌唑分子印迹聚合物前功能单体选择研究

为制备腈菌唑(M)分子印迹聚合物,建立了选择合适的功能单体以及功能单体添加量的方法。利用紫外光谱法研究α-甲基丙烯酸(MAA)、丙烯酰胺(AM)与M作用形式、作用强度、最佳浓度比和形成的结合位点数。结果表明,M与两种功能单体都会形成氢键;M的三唑环共轭双键的π电子吸收能量跃迁到π*共轭反键轨道,氢键的形成会使π→π*的吸收带发生迁移,最大吸收波长随着体系功能单体浓度增加而发生红移。M与两种功能单体最佳浓度配比分别为:M∶MAA=1∶4和M∶AM=1∶2。M与两种功能单体都具有结合能力,且结合力较强。采用AM为功能单体合成的分子印迹聚合物对M具有更好的稳定性和特异识别能力。     

Ti类氦Kα线在高温稠密等离子体中的漂移

采用离子球模型,通过自洽求解Dirac方程和Poisson方程,得到类氦Ti离子Kα线系的两条电偶极辐射光谱能量随不同等离子体环境的变化关系.同时分析了束缚电子交换能随等离子体环境的变化规律.结果表明：光谱能量漂移量随等离子体电子密度变化呈现出很好的线性关系.对此,拟合得到Ti类氦Kα线光谱能量漂移量随等离子体环境参数变化的公式,对探索高温高密度等离子体诊断方法具有一定意义. 关键词： 类氦离子 自洽场离子球模型 光谱漂移 等离子体诊断     

C–H…N hydrogen bonding in an overlayer of s-triazine physisorbed on a graphite surface

The structure of a crystalline monolayer of 1,3,5-triazine has been characterised using X-ray diffraction. The monolayer is found to exhibit a hexagonal unit cell with a lattice parameter of 6.161(5)?Å, indicating the formation of C–H…N hydrogen bonds. DFT simulations have been performed exhibiting close agreement with the experimental structure. By comparing the strength of the intermolecular interactions both with and in the absence of Van der Waals corrections, it is possible to estimate an interaction strength for the weak C–H…N hydrogen bonds.     

Intramolecular hydrogen bonds in the phenylazomethine biomolecules

The FTIR spectra of the solutions of biologically active molecules (screened phenylazomethines) in CCl₄ are studied. The role of the OH- and N=C groups in the formation of the intramolecular H bonds is analyzed. The analysis of the FTIR spectra shows that three types of H bonds (O-H…O-H, O-H…N=C, and O-H…O-H…N=C) are possible in the molecules under study. A correlation of the H-bond formation in the phenylazomethine molecules and the antivirus properties of such molecules is revealed. The antivirus activity is observed for molecules that exhibit intramolecular O-H…O-H…N=C bonds in the absence of free hydroxyls. The antivirus activity decreases when the molecule contains additional OH groups that are not involved in H bonds.     

Theoretical and Experimental Study of the Conformation and Vibrational Frequencies of N‐Acetyl‐L‐alanine and N‐Acetyl‐L‐alaninate

The vibrational frequencies of N‐acetyl‐L‐alanine (NAAL), its potassium salt (NAALK) and its free anionic form (NAAL^?) are calculated using density functional theory (B3LYP) combined with the 6‐311 + + G(d,p) basis set. The experimental Raman spectrum of solid NAALK and the scaling factors for calculated values are discussed as well. The three species are characterized by intramolecular NH…O hydrogen bonds leading to the formation of a five‐membered ring. As indicated by the intramolecular (N)H…O distances and by the ν(NH) frequencies, the strength of the intramolecular hydrogen bond is ordered as follows: NAAL^? < NAALK < NAAL^?. Owing to their difference in the coupling with other vibrational modes, the in‐plane and out‐of‐plane vibrations do not reflect the strength of the hydrogen bond.     

Hydrogen bonds of extremely high polarisability between molecules adsorbed on silica gel — an IR investigation

The adsorption on silica gel of a series of electron pair donors with a variation of the pKa value from 12 up to the range of negative values was subjected to IR spectroscopic investigation. Adsorption is effected via hydrogen bonds with the OH groups of the surface, indicated by the disappearance of the band of the free OH groups (3750 cm⁻¹) and by the occurrence of a broad band at smaller wave numbers. The shift is roughly proportional to the pKa value. Furthermore, a continuous absorption is observed as the pKa value increases. This shows that protons become detached from the SiOH groups and hydrogen bonds of type NH⁺…N form between the adsorbed molecules. A double minimum potential well occurs in these hydrogen bonds, which are extremely easily polarisable. The anomalous proton conductivity to be expected sometimes in the presence of such groupings is discussed.     

Infrared Study of the Molecular Complexes of Parafluoro-Phenol with Alkylbenzenes in n-Hexane

Abstract

The specific interaction between parafluorophenol and alkylbenzenes in n-hexane has been studied using infrared spectrometry. The absorption spectra of different donor-acceptor couples exhibit bands in the region 3600–3500 cm^?1 which are characteristic for the formation of hydrogen bonded complexes OH…eπ. The observed frequency shifts are between 67 and 92 cm^?1, and the values of the complexation constant range from 0.41 to 1.51 dm³ mol^?1. The values of the free enthalpy of interaction -ΔG are situated between -2.22 and+1.05 kJ.mol^?1, while the affinity ratio varies from 3.08 to57.98.

The established relations between the strength of the complexes and the frequency shift, or. The calculated correlation coefficients and affinity ratios allow to discuss both the electrordonating effects and the steric effects of the substituents implanted on the aromatic ring of the proton acceptor.     

Spectroscopic properties of pharmacologically active phenols

The IR Fourier-transform spectra of pharmacologically active phenol molecules in solutions in CCl₄ and in the crystalline state have been studied. Phenol derivatives with different directivities and different levels of pharmacological efficiency have been examined. Based on analysis of the IR spectra of screened phenols, the antimicrobial activity of phenols with free hydroxyl groups has been shown to be highest. The high antimicrobial activity of aminophenols is related to the formation of intramolecular hydrogen bonds. For aminophenols that are active against herpesviruses, O-H...N hydrogen bonds are formed in molecules. The main characteristic of the high antiviral activity against A-type influenza is predominance of intramolecular hydrogen bonds of the O-H...O=C type in molecules. Sulfur-containing aminophenols, which manifest activity against HIV infection, are characterized by the occurrence of hydrogen bonds that involve the participation of the OH, NH, and SO₂ groups.     

利用核磁共振研究准轮烷的振荡行为

利用含巯基苯醚链和含羟基苯醚链分别与缺电子联吡啶大环化合物CPQT形成准轮烷,并利用变温核磁共振技术研究了准轮烷的振荡行为.     

水玻璃化过程的氢键结构特性

为了解玻璃化过程氢键结构特性,采用分子模拟的手段计算了三种压力下的水玻璃化过程氢键的角度、距离、生命期和数量.计算结果显示:(i)氢键角度呈现泊松分布的特征,随着温度降低分布氢键角度分布范围变窄,峰值变高,在0～13°范围,随温度降低,分布数值变大;而在大于13°,随温度降低,分布数值变小;(ii)氢键距离也呈现泊松分...     

Fourier transform IR spectroscopic study of substituent effect in aromatic amino acids on the zwitterion–neutral molecule tautomeric equilibrium

Four aromatic amino acids (p-aminobenzoic, 4,6-diaminoisophthalic, o-aminobenzoic, and methylene-bis-anthranilic) were studied by FTIR spectroscopy. The first two molecules were found to exist in the solid phase exclusively in neutral form and the latter two in coexisting neutral and ionic forms. The shift of the tautomeric equilibrium from neutral molecule to zwitterion is determined by the character of substitution, molecular conformation, and the possibility of noncovalent bonds formed between the functional groups. The separation of charges becomes possible only if the conformers of the molecule include a structure with an OH….N intramolecular hydrogen bond. The proton is completely transferred from the acid group to the amino group when the strong intermolecular hydrogen bonds can stabilize the formed zwitterion. Otherwise, uncharged complexes with different degrees of proton transfer to the amino group are formed.     

Switching of hydrogen bonds of water in ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate

We have investigated temperature‐induced Raman spectral changes of deuterated water in an ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF₄]), between room temperature and 77 K. The comparison of the OH and OD stretching vibrational spectra at 77 K shows that the strength of the hydrogen bonds in [bmim][BF₄]–water mixtures strongly depends on the type of water, i.e. H₂O and D₂O. In the [bmim][BF₄]–D₂O system, remarkably strong hydrogen bonds form at low temperatures, but they switch to nearly free hydrogen bonds on heating. Copyright © 2013 John Wiley & Sons, Ltd.