Fragmentation of Some Hydrazino- and Hydroxylaminohalophosphines Under Electron Impact

During the past several years compounds containing P-N bonds have been the object of a number of investigations,² many of them motivated by the conjecture that pπ-dπ bonds can form between these two atoms. Recently the behavior of the halophosphonitriles,^3–6 whose bonding is thought to involve extensive pπ-dπ delocalization,⁷ and the aminohalo-phosphines,⁸ which contain only a single P-N fragment, toward electron bombardment has been described. Since the framework over which π bonding can occur in the hydrazino- and hydroxylaminohalophosphines⁹ is intermediate between these other two classes of compounds we would like to report comparable studies for these latter compounds.     

Interaction between ZnHEDP corrosion inhibitor and a surface of carbon steel

The interaction between the metal-complex corrosion inhibitor ZnHEDP (a zinc complex with 1-hydroxy-ethylidene-diphosphonic acid) and a surface of 20kp steel is studied. It is shown that the chemical interaction between the corrosion inhibitor and the steel surface leads to the formation of a strong covalent bond of Zn-O-P-Fe atoms, and to Fe atoms transitioning into a high-spin state. Thermal action on the protective film results in the breaking of C-P bonds and the detachment of a carbon-containing fragment. At temperatures above 525 K, the Zn-O-(P-O)-Fe complex breaks down.     

可聚合萘酰亚胺类衍生物的合成及光谱研究

以4-溴-1,8-萘酐和4-硝基-1,8-萘酐为原料制备了分别含碳-碳双键和硅氧烷结构的可聚合萘酰亚胺衍生物4-二甲胺基-1,8-萘酐、4-二甲胺基-N-烯丙基-1,8-萘酰亚胺、4-硝基-N-烯丙基-1,8-萘酰亚胺和4-硝基-N-[(3-三甲氧基硅基)丙基] -1,8-萘酰亚胺. 通过¹H、¹³C及多种二维核磁共振（NMR）技术表征了其分子结构,完成了氢和碳的谱峰归属. 利用紫外吸收光谱与荧光发射光谱研究了这些化合物的光学性质,并讨论了取代基对这些化合物荧光性质的影响.      

某些五配位磷化合物的31P NMR谱表征

分析归纳了几种类型五配位磷化合物的³¹P化学位移规律性.并着重讨论了产主的原因.     

Mass Spectroscopy of the Antileukemic Drug MGBG and Related Bis(Amidinohydrazones) [‘Bis(Guanylhydrazones)’]

The first study on the mass spectroscopy of various bis(amidinohydrazones) is reported. The compounds studied included the investigational antileukemic drugs methylglyoxal bis(amidino-hydrazone) [‘methylglyoxal bis(guanylhydrazone)’, MGBG] and glyoxal bis(amidinohydrazone), as well as seven mono- and dialkylglyoxal analogs thereof. The results indicate that the free bases of these high-melting compounds are volatilized well enough to allow a facile detection of the molecular ions and to make mass spectroscopy of the underivatized compounds a suitable method for the verification of the identity of the substances. This result is of importance considering the development of novel analogs and derivatives. A compilation of electron-impact mass spectra is reported and possible fragmentation routes are outlined. The fragmentation of the various congeners appears to occur essentially similarly, the main paths involving breakage of the carbon-carbon single bond in the glyoxal moiety or breakage of either one of the nitrogen-nitrogen single bonds.     

偏磷酸钙玻璃陶瓷的Raman光谱分析

测量了Ca/P摩尔比为0.45的偏磷酸钙玻璃及其在300~700℃下结晶化处理获得玻璃陶瓷的拉曼光谱,对谱峰的振动模式进行了指认,利用拉曼振动频率计算了P—O键长。光谱分析发现偏磷酸钙玻璃在300℃已经开始了结晶相变,不同温度下,sν(PO2)和sν(POP)谱带的振动频率基本不变,随着温度提高,谱峰强度增加,并出现了精细的指纹结构;玻璃陶瓷的表面和内部的结构不同,表面结晶化程度高于内部;结晶过程中,P—O键平均键长会发生变化,随着结晶化程度的提高,骨架上(POP)的P—O键平均键长减小,由159.96 pm变为158.27 pm,侧链(PO2)上的P—O键长增大,由147.90 pm变为149.02 pm。     

How universal are hydrogen bond correlations? A density functional study of intramolecular hydrogen bonding in low-energy conformers of α-amino acids

Hydrogen bonding is one of the most important and ubiquitous interactions present in Nature. Several studies have attempted to characterise and understand the nature of this very basic interaction. These include both experimental and theoretical investigations of different types of chemical compounds, as well as systems subjected to high pressure. The O–H..O bond is of course the best studied hydrogen bond, and most studies have concentrated on intermolecular hydrogen bonding in solids and liquids. In this paper, we analyse and characterise normal hydrogen bonding of the general type, D–H...A, in intramolecular hydrogen bonding interactions. Using a first-principles density functional theory approach, we investigate low energy conformers of the twenty α-amino acids. Within these conformers, several different types of intramolecular hydrogen bonds are identified. The hydrogen bond within a given conformer occurs between two molecular groups, either both within the backbone itself, or one in the backbone and one in the side chain. In a few conformers, more than one (type of) hydrogen bond is seen to occur.

Interestingly, the strength of the hydrogen bonds in the amino acids spans quite a large range, from weak to strong. The signature of hydrogen bonding in these molecules, as reflected in their theoretical vibrational spectra, is analysed. With the new first-principles data from 51 hydrogen bonds, various parameters relating to the hydrogen bond, such as hydrogen bond length, hydrogen bond angle, bond length and vibrational frequencies are studied. Interestingly, the correlation between these parameters in these bonds is found to be in consonance with those obtained in earlier experimental studies of normal hydrogen bonds on vastly different systems. Our study provides some of the most detailed first-principles support, and the first involving vibrational frequencies, for the universality of hydrogen bond correlations in materials.     

有机分子PTCDA在P型Si单晶(100)晶面的生长机理

对PTCDA的分子结构及其化学键的形成进行了分析,并讨论了晶面指数（100）Si单晶的晶格结构。在此基础上,评述了PTCDA分子在P-Si单晶（100）晶面上生长的机理,并制备了样品PTCDA/P-Si（100）。利用XRD对样品测试得出,在P-Si（100）晶面上沉积的PTCDA薄膜中仅存在α物相。利用XPS对样品测试得出,在其界面层中PTCDA酸酐中的4个羟基O原子与C原子结合,其结合能为532.4 eV;苝核基团外围的8个C、H原子以共价键结合,其结合能为289.0 eV;在界面处,悬挂键上的Si原子与PTCDA酸酐中的C、O原子结合,形成C-Si-O键及C-Si键,构成了界面层的稳定结构。     

磷酸钠结构的高温拉曼光谱研究

用高温拉曼光谱仪测定了固态和熔融态磷酸钠(Na3PO4)晶体的光谱,分析了磷酸钠晶体的结构及其随温度的变化。通过对从常温谱到高温谱的解析,得出主峰波数随温度的变化及主峰半高宽的变化,可以观察到在600 K附近及1773 K有两个相变产生。此外,磷酸钠晶体的相关高温DSC检测分析,也和拉曼谱中发现的两个相变符合。量子化学理论计算同时对该体系的P-O键振动和平均键长进行了模拟,随着键长的增加,对应的振动频率会降低。还确认了磷酸钠Raman光谱中各个峰的归属,938 cm-1波数处的峰属于(PO4)3-中P-O键的对称伸缩振动,是Na3PO4的特征峰,425及580 cm-1处峰属于磷氧四面体的弯曲振动。     

The dislocations in graphene with the correction from lattice effect

The dislocation widths and Peierls stresses of glide dislocations and shuffle dislocations in graphene have been studied by the improved Peierls-Nabarro (P-N) equation which contains the discrete correction. The discrete parameter is obtained from a simple dynamic model in which the interaction attributed to the variation of bond length and angle was considered. The restoring force in the improved P-N equation is given by the gradient of the generalized stacking fault energy surface (γ-surface). Our calculation shows that the widths of the shuffle dislocation and the glide dislocation are narrow and the width of the shuffle dislocation is about twice wider than the glide dislocation. The Peierls stress of a shuffle dislocation is one order of magnitude smaller than that of a glide dislocation. As a consequence, the shuffle dislocation moves more easily than the glide dislocation.     

吸附于纳米磷化镓粉体表面碱性品红的拉曼光谱(英文)

本文中,对吸附于纳米磷化镓(GaP)粉体表面的碱性品红拉曼光谱进行了研究。通过将吸附碱性品红与纯碱性品红晶体样品的拉曼光谱进行对比、分析可知,碱性品红在纳米GaP粉体表面发生了化学吸附。在吸附碱性品红样品的拉曼光谱中,位于1200~1320cm-1范围内的光谱特征表明可能有新的化学键(P-O-C+或Ga-O-C+)形成。碱性品红分子的中央碳正离子(C+)与GaP表面具有孤对电子的氧原子形成配位键。红外光谱结果表明,氧原子与纳米GaP粉体表面的磷原子或镓原子键合,以P-O,Ga-O或P-O-Ga形式存在于GaP表面。碱性品红分子的呼吸振动,N-苯环伸缩振动,以及苯环C-C伸缩振动散射强度与纯碱性品红晶体样品相比皆有所增强。N-苯环伸缩振动散射强度增加意味着N原子是除C+离子以外的另一个可以与GaP表面发生化学作用的活性中心,这种化学作用是由N原子与GaP表面存在共轭效应造成的。     

用HREELS研究氢在GaAs和InP的(111),(111)表面上的吸附

氢在GaAs和InP表面上的吸附可以用高分辨率电子能量损失谱(HREELS)来探测。Ga—H,As—H,In—H和P—H键的伸缩振动各自对应于不同的能量损失。但是As—H振动极容易和Ga—H振动追加声子损失相混淆,只有从损失峰的相对强度比较上来区别。实验得到吸附的氢与表面原子的成键情况取决于表面的原子结构及电子分布。对于GaAs(111)面,低暴露量时只形成Ga—H键,而高暴露量时还可以形成As—H键。而InP(111)表面由于是经过磷气氛退火处理的,在低暴露量下In—H与P—H键均可形成。InP(Ⅲ)面上只看到P—H损失峰,说明这个表面是完全以P原子结尾的。在(Ⅲ)面上出现小面的情形,则表面Ⅲ族和Ⅴ族原子均可同氢成键。 关键词：     

用HREELS研究氢在GaAs和InP的（111），（III）表面上的吸附

氢在GaAs, 和InP 表面上的吸附可以用高分辨率电子能量损失谱(HREELS) 来探测.Ga-H侧, As-H , In-H 和P-H 键的伸缩振动各自对应于不同的能量损失. 但是A-H 振动极容易和Ga-H 振动追加声子损失相混淆, 只有从损失峰的相对强度比较上来区别。实验得到吸附的氢与表面原子的成键情况取决于表面的原子结构及电子分布. 对于GaAs (1 1 1)面, 低暴露量时只形成Ga-H 键, 而高暴露量时还可以形成As-H 键.而InP(1 1 1 ) 表面由于是经过磷气氛退火处理的, 在低暴露量下In 一H 与P一H 键均可形成. InP (III) 面上只看到P-H 损失峰, 说明这个表面是完全以P 原子结尾的. 在(1 1 1 ) 面上出现小面的情形, 则表面III族和V族原子均可同氢成键. 关键词：     

Remark on the application of the effective hamiltonian method for random systems

We compare two versions of the effective Hamiltonian method applied to random bond systems. In one randomness is treated in a kind of the mean field approximation, whereas in the other the relevant arrangements of bonds are explicitly accounted for. Calculations for three dimensional systems of mixed ferromagnetic Heisenberg and Ising bonds show that although the T_c vs p (concentration of Heisenberg-loke interactions) curve in the second approach lies closer to the results of high temperature series general features in both approxsimations are quite similar.     

纳米磷化镓粉体还原氦过程的Raman光谱分析

利用Raman光谱对还原氮后的纳米磷化镓(GaP)粉体进行了表征。结果表明：纳米GaP粉体表面含有Ga-O，P-O和H-O化学键。此外，进行氮还原过程后，在Raman位移约为1700～3300cm^-1范围内(相当于709～800nm或1．55～1．75eV)，纳米GaP的Raman光谱出现了一个宽、强荧光发射峰；而在未进行通氮处理的纳米GaP Raman光谱中，没有观察到该荧光峰的存在。本文对该荧光发射峰的起因作了初步分析。     

On some hydrogen bond correlations at high pressures

Structural data from in situ high pressure neutron diffractions studies are analysed to show that the measured lengths of O?H and H---O pairs in hydrogen bonds follow the correlation between them established from 0.1 MPa data on different chemical compounds. In particular, the accepted view in literature that the high pressure data on ice VIII differ from it is not supported. For compounds in which the O?H stretching frequencies red shift under pressure, it is shown that wherever structural data is available, they follow the stretching frequency versus H---O (or O---O) distance correlation. For compounds displaying blue shifts with pressure, an analogy appears to exist with ‘improper’ hydrogen bonds. Another pressure effect expected is the symmetrization of a hydrogen bond with evolution of the double-welled, hydrogen bond potential into a single-well potential. Using the results from some recent ab initio electronic structure studies, we show that the bulk modulus shows a discontinuity at this point and this can be taken as signature for hydrogen bond symmetrization. This is supported by analysing a few available experimental data.     

Angle-resolved photoelectron spectroscopy of intramolecular hydrogen bond systems: 2-chloroethanol and 2-bromoethanol

He(I) photoelectron angular distributions of typical intramolecular hydrogen bond systems, 2-chloroethanol and 2-bromoethanol, were measured. The intramolecular hydrogen bonds were found not to influence the photoelectron angular distributions for the halogen atom lone pair bands of these compounds. This result is useful for spectral band assignments.     

Photoluminescence enhancement of InP treated with activated hydrogen

A large enhancement of the photoluminescence intensity emitted by a (100)-oriented InP surface after exposure to activated hydrogen, indicating a sharp reduction of the surface recombination rate is reported in this work. It is shown, using capacitance-voltage measurements performed on metal-insulator-semiconductor structures, that the hydrogen treatment results also in a strong pinning of the interface Fermi level. These phenomena are interpreted on the following basis: (i) neutralization by hydrogen species of active recombination centers which are deemed to be phosphorus dangling bonds; (ii) creation of pinning surface states due to the formation of volatile phosphorus hydride compounds freeing excess indium atoms.     

The effect of disulfide bonds on protein folding,unfolding, and misfolding investigated by FT–Raman spectroscopy

Disulfide bond is relevant to many protein folding/unfolding functions and conformational diseases. To elucidate the effects of disulfide bonds on protein folding, unfolding, and misfolding, we performed Fourier transform–Raman measurements on serial chemical‐induced denaturations of bovine serum albumin (BSA). By directly monitoring Raman stretching at S–S (~507 cm⁻¹), S–H (~2566 cm⁻¹), amide I (1655 cm⁻¹ for α‐helix; 1667 cm⁻¹ for β‐sheet structure), and amide III (>1300 cm⁻¹ for α‐helix; 1246 cm⁻¹ for β‐sheet structure), the status of disulfide bonds and secondary structure of BSA at different states were elucidated. Both disulfide bonds and secondary structure (mostly in α‐helix) of BSA appeared relatively stable even when the protein was unfolded by urea solution. However, disulfide bonds were completely reduced and protein secondary structure changed from α‐helix to a relatively β‐sheet dominant when the protein was modified by the mixed solution of urea and dithiothreitol (urea/DTT). Adhering to these structural changes, the protein proceeded to different degrees of polymerization. BSA would aggregate into a high molecular mass (over 700 kDa) of protein ensemble when it was exposed to the mixed urea/DTT solution. An irreversible change in S–S/S–H conversion and secondary structure was responsible for protein misfolding. We demonstrate here that Fourier transform–Raman directly probe S–S/S–H conversion and secondary structural change of BSA at different states, and these results clearly indicate that disulfide bonds and secondary structure of BSA serve as concrete frameworks to stabilize protein structure. As the frameworks collapse, the protein undergoes an irreversible structural change and results in protein misfolding. Copyright © 2016 John Wiley & Sons, Ltd.     

Mechanism study of hemicellulose pyrolysis by combining in-situ DRIFT,TGA-PIMS and theoretical calculation

As one of the major components of lignocellulosic biomass, the current understanding on pyrolysis mechanism of hemicellulose is relatively limited compared to that of cellulose due to its random and complicated structure. Here, we reported an in-depth study on hemicellulose pyrolysis by combining advanced experimental techniques and quantum chemical calculation, using xylose, xylobiose and xylan as the model compounds. The structural evolution during pyrolysis was firstly characterized via in-situ diffuse reflectance infrared Fourier transform spectroscopy. The corresponding two-dimensional perturbation correlation infrared spectroscopy analysis shows that the dissociation of side chains dominates in the initial stage of xylan pyrolysis, followed by the cleavage of glycosidic bond and the opening of xylopyranose ring. The release behaviors of condensable vapors from hemicellulose pyrolysis obtained by thermogravimetric analyzer coupled with photoionization mass spectrometry indicate that the pyrolysis of xylan polymer with more side chains is prone to produce small compounds via ring rupture reactions compared to that of xylose and xylobiose. The possible reaction pathways of xylan pyrolysis were proposed based on the experimental results and were further confirmed via quantum chemical calculation. This work expands the size of model compounds from common monomers and dimers without side chains to larger tetramers with side chains. It was found that the dissociation of side chains and the cleavage of glycosidic bonds are competitive reactions. The backbone of xylan is decomposed following the dissociation of side chains to yield furfural, dianhydro xylose and other small compounds.