电子激发和溶剂效应对芴酮-甲醇分子间氢键增强现象的理论研究 (cited: 1)

理论研究了电子激发和溶剂效应导致的芴酮-甲醇复合体系中分子间氢键增强现象．通过基态和激发态性质的计算,不仅展示了分子间氢键键长的变化以及变化在振动光谱中的影响,而且揭示了导致氢键变化的内在物理机制：溶质分子的电子激发及溶剂化效应引起的电子重新分布,增大了溶质和溶剂分子的偶极矩,导致了它们之间的相互作用的增大,并最终加强了分子间氢键的强度．还分别对处于液相及气相中的复合体的基态和激发态的几何结构、红外谱、复合体及构成分子的偶极矩进行了理论计算,结果阐明了电子激发与溶剂化效应对氢键变化的贡献,同时还发现只有进一步引入溶剂化效应,复合体的基态、激发态的性质才能与实验达到精确一致．所有激发态均采用所开发的基于含时密度泛函理论解析计算一阶、二阶激发态能量导数的方法．     

用密度泛函方法研究质子化苯基丙酮-水团簇

应用密度泛函B3LYP/631+G(d,p)计算方法,对质子化苯基丙酮水团簇这个弱相互作用体系进行了全自由度能量梯度优化,得到该系列团簇的稳定结构.结果表明,H+C8H8OH2O团簇的形成过程为一无能垒的反应过程,在质子与C8H8O分子中O原子的距离为1.015时达到平衡几何.对H+C8H8O(H2O)n(n=1,2,3)团簇,质子位于C8H8O分子和水分子之间,且随着团簇尺寸的增加,质子与C8H8O分子中O原子之间的距离也增加;C8H8OH+H2O可以视为溶剂壳.而对H+C8H8O(H2O)n(n=4,5,6,7,8)团簇,质子位于两个水分子之间,形成H5O2+结构,即C8H8OH5O2+为该系列团簇的中心结构,新增加的水分子以从不同方向进攻这个中心的方式形成更大尺寸的团簇.     

甘蔗渣高沸醇木质素光谱分析与结构测定

甘蔗渣高沸醇(HBS)木质素是高沸醇溶剂法制浆过程中得到的高分子材料。从红外谱图显示,在1 700和1 328 cm-1处存在吸收峰值,说明HBS木质素存在非共轭羰基作用。紫外谱图在201 nm处存在n→π*电子跃迁。表明有较大的不饱和性。从1H NMR图谱中看出存在明显的紫丁香基苯和愈疮木基环结构。实验测定了甘蔗渣HBS木质素的元素组成和甲氧基含量,并计算得到经典的C₉结构模型。其结构形式为C₉H_9.79O_2.58(OCH₃)0.75。其重均分子量测定结果为2 674 g·mol-1。     

N-取代酰胺-二苯酮体系光化夺氢反应活泼自由基的ESR研究

本文用自由基捕捉剂2,3,5,6-四甲基亚硝基苯(ND)及苯亚甲基叔丁基氮氧化物(PBN)与ESR相结合的方法研究了十二种取代酰胺RC₆H₄NHC(0)CH₃(R-CH₃、Cl、Br、H、NO₂)、C₆H₅N(R)C(0)CH₃(R=CH₃、C₂H₅)及HC(0)NR₂(R-CH₃、C₂H₅)与二苯酮光化夺氢反应中的活泼自由基。结果表明: 1.对于RC₆H₄NHC(0)CH₃,二苯酮夺取氮上H形成R-C₆H₄NC(0)CH₃自由基。 2.对C₆H₅N(R)C(0)CH₃及HC(O)NR₂,二苯酮夺取与羰基相连的甲基氢、羰基上氢及与N相连碳上的氢分别形成 C₆H₅N(R)C(0)CH₂、C(0)NR₂、C₆H₅N(CHR')C(0)CH₃及。     

The hydrolysis mechanism and kinetic analysis for COS hydrolysis: A DFT study

Density Functional Theory (DFT) was utilized to study the hydrolysis mechanism and kinetic analysis of carbonyl sulfide (COS). The structures of reactants (R), transition states (TS), intermediates (IM) and products (P) were analyzed and a conclusion reached that hydrolysis mechanism of COS occurs in two paths with One path as a C=S path and the other as a C=O path and all featuring potential for forming H₂S and CO₂. Function change analysis of COS hydrolysis indicated the rate-determining step of COS hydrolysis was the first elementary reaction as OH and H in H₂O attacked C=O and S=O in COS, respectively, with the two paths parallel and competitive and the C=S path more reactionary than the C=O path. Influence on each elementary reaction was also not consistent with reaction temperature increase. The study also included further investigation of the COS catalytic hydrolysis.     

IR Spectra of Derivatives of Immunotropic 8-Azasteroids

By the method of IR Fourier spectroscopy with the use of numerical differentiation of spectral line profiles we have studied the spectra of some structural and functional derivatives of immunotropic 8-azasteroids in the region of C=O and C=C bonds (1800–1400 cm^–1). We have established the dependence of vibration frequencies of the C=O and C=C groups on the size of the ring D, the presence of heteroatoms (O, S) in the ring D, transformations in the -acyl--aminovinylcarbonyl fragment and in its adjacent positions of the heterosteroid skeleton, and the composite character of the absorption bands that are due to the vibrations of the C=O and C=C groups. The role of the structural and stereoelectronic factors in the observed group frequencies of 8-azasteroids is discussed.     

表面氧钝化碳化硅纳米团簇电子结构和光学性质的第一性原理研究

基于密度泛函理论(DFT)和广义梯度近似(GGA),对氧钝化条件下4H-SiC纳米团簇的电子结构和光学性质进行了研究。计算了不同直径的4H-SiC纳米球氧钝化后的能带结构、电子态密度和光学性质。团簇的尺度在0.4~0.9 nm之间,构建表面仅存在硅氧双键和表面仅存在碳氧双键的两种模型。研究表明硅氧双键和碳氧双键所引起的缺陷态位于原4H-SiC的价带和导带之间,并且缺陷态与价带顶的能量差随纳米团簇颗粒直径的增大而减小;缺陷态主要是由Si原子外层电子和氧原子外层电子轨道杂化引起的。同时,由于氧的存在,对碳化硅的结构产生一定的影响,这也是缺陷态形成的一个原因。另外,碳氧双键和硅氧双键钝化对4H-SiC纳米团簇的光学性质有着不同的影响。在表面仅存在C=O的情况下,4H-SiC纳米团簇表现出各向同性的性质。在表面仅存在Si=O的情况下,4H-SiC纳米团簇表现出各向异性的性质。     

Microwave Spectrum of 2-Methylcyclohexanone

The five lowest J rotational transitions of (13)C(16)O have been measured by saturation-dip spectroscopy to an accuracy of about 2 kHz, employing phase-stabilized backward-wave oscillators (BWOs). These highly precise measurements cover the transitions from J = 2 <-- 1 to J = 6 <-- 5 with frequencies ranging from 220 to 661 GHz. For each of the five observed rotational transitions, the narrow linewidths of the saturation dips (about 20 kHz) permitted the resolution of the hyperfine splitting for the first time. This splitting is caused by the (13)C-nuclear spin-rotation interaction yielding a value for the nuclear spin-rotation coupling constant of C(I)((13)C(16)O). If combined with the beam measurements (C(I)((13)C(16)O) = 32.63(10) kHz), a slight J-dependence of the spin-rotation coupling constant can be determined (C(J) = 30 +/- 13 Hz). In addition, we have measured in the Doppler-limited mode several higher J rotational line positions of (13)C(16)O up to 991 GHz with an accuracy of 5 kHz. The two line positions (J = 12 <-- 11 and J = 14 <-- 13) were recorded by multiplying BWO frequency with an accuracy of 100 kHz. The rotational transitions J = 17 <-- 16 and J = 18 <-- 17 were measured with an accuracy between 15 and 25 kHz by using the Cologne sideband spectrometer for terahertz applications COSSTA. Copyright 2000 Academic Press.     

The oxidation of fullerene[C60] with various amine N-oxides under ultrasonic irradiation

The reaction of C60 with various amine N-oxides such as 3-picoline N-oxide (Aldrich 98.0%), pyridine N-oxide hydrate (Aldrich 95.0%), quinoline N-oxide (Aldrich 97.0%), isoquinoline N-oxide (Aldrich 98.0%) under ultrasonic irradiation in air at 25-43 degrees C causes the oxidation of fullerene[C60(O)n] (n=1-2 or n=1). The MALDI-TOF MS, UV-vis spectra, and HPLC profile confirmed that the products of fullerene oxidation are [C60(O)n] (n=1-2 or n=1).     

Intramolecular interactions of N-(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-2-hydroxyphenyl)acetamide derivatives

IR-Fourier spectroscopy methods are adopted to the study of intramolecular interactions occurring in CCl₄ solutions of antivirally active derivatives of N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide. Analysis of IR spectra has shown that intramolecular H-bonds O–H···O=C and N–H···O=C are formed in solutions of these compounds. The O–H···O=C and N–H···O=C bond strengths and the direction of the equilibrium shift between the two types of conformers depend on the type of carbonyl group substituent. An intramolecular O–H···O=C H-bond is characteristic of highly active derivatives of N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide.     

Si3Xn (X=C,O,N;n=1,2)团簇的密度泛函研究

使用密度泛函理论(DFT)的杂化密度泛函B3LYP方法在6-31G*基组水平上对Si3Xn(X=C,O,N;n=1,2)团簇各种可能的构型进行几何结构优化,预测了各团簇的最稳定结构.并对最稳定结构的电子结构、振动特性、成键特性和电荷特性等进行了理论研究.结果表明团簇的几何结构都是平面结构,通常Si3X2出现是Si-X键,较少出现X-X键;而Si3X中出现Si-X键和Si-Si键共存,Si3Xn(X=C,O,N;n=1,2)团簇的电荷布局分布表明这种电荷转移的作用使得团簇中所有X原子呈负电性,Si原子显正电性.处于不同位置的Si原子呈不同大小布局数,而且由于Si3X2的对称性,2个X负电性相同.     

Determination of the interaction using FTIR within the components of GPE based on the synthesized grafted polymer

An oxyethylene chain (–CH₂–CH₂–O–) grafted polymer (P(MMA–MAh)–PEGME) was synthesized by reacting poly(ethylene glycol) monomethyl ether (PEGME) with the copolymer of poly(methyl metacrylate–maleic anhydride) (P(MMA–MAh)) and endcapping the residual carboxylic acid with methanol. Rectorite modified with dodecyl benzyl dimethyl ammonium chloride (OREC) was used as a filler additive to modify gel polymer electrolytes (GPE) that consisted of P(MMA–MAh)–PEGME used as polymer matrix, propylene carbonate (PC) as plasticizer and LiClO₄ as lithium ion producer. Characterization of interaction of the polar group of C=O or C–O–C in PC and grafted polymer with Li⁺ and OH group on OREC surface has been thoroughly examined using Fourier transform infrared (FTIR), respectively. The quantitative analysis of FTIR shows that the absorptivity coefficients (a) of polymer/LiClO₄, PC/LiClO₄, PC/OREC and polymer/OREC are 0.705, 0.113, 0.430 and 0.500, respectively, which means that the Li⁺ or OH bonded polar group of C=O and C–O–C is more sensitive than free C=O and C–O–C in FTIR spectra. The limited values of bonded C=O and C–O–C equivalent fraction of polymer/LiClO₄, PC/LiClO₄, PC/OREC and polymer/OREC are 33%, 94%, 60% and 22%, respectively, which implies that the interaction within the components is reversible and the intensity of interaction is ordered as PC/LiClO₄, PC/OREC, polymer/OREC and polymer/LiClO₄.     

醋酸铜和多氮杂环配体配合物的低热固相合成

室温下 ,醋酸铜分别与 1,2 ,4 三氮唑和苯并三氮唑充分研磨 ,能发生固相配位反应 ,研磨过程有醋酸逸出 ,杂氮配体取代了醋酸与Cu (Ⅱ )配位形成混配配合物 ,元素分析表征表明产物的组成为Cu(C2 H2 N3) (Ac)·H2 O和Cu (C6 H4 N3) (Ac)·H2 O。红外光谱图显示了杂氮配体的 CN ,醋酸的 CO 和水的O—H特征吸收。固相反应为合成新配合物提供了一条快速、温和及不需溶剂的途径。     

烷基极化效应与羰基13C化学位移

对羰基化合物中羰基碳的¹³C NMR化学位移与烷基（R）极化效应的内在关系 进行了研究. 结果表明：分子中R的极化效应增加使羰基碳的¹³C化学位移值升 高,其关系可表示为δ=a+b·ΣPEI(R),其中a、b为系数,PEI（R）为R极化效应指数.
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Infrared Spectra of Negative Ions of Amides

Abstract

The anionic derivatives of a series aliphatic, arylaliphatic and aromatic compounds containing amide group were investigated by means of infrared spectroscopy. The stretching vibration frequencies of the amide C=O, the ketone C=O and the N-C(Ph) in the N-anions of the studied compounds were assigncd: the amide C=O shifts 76-180 cm^?1 downward depending on the substituents; the band intensity increases 2.5-3 times. It was found an excellent correlation between the carbonyl stretching vibration frequencies of the studied N-anions with the Hamrnett CJ constants of the substituents.     

基于第一性原理的CVD金刚石涂层表面氧原子作用分析

采用第一性原理方法研究了氧原子在CVD金刚石涂层表面吸附形成的两种氧掺杂结构的差异及脱附CO的难易程度.仿真计算结果表明：氧原子在金刚石表面顶位和桥位吸附形成C=O羰结构和C-O-C醚结构,改变与其直接成键的局部金刚石结构;C-O-C结构吸附能比C=O结构大,其结构更加稳定;C=O结构断键脱附形成CO的能垒比C-O-C结构更低,CVD金刚石涂层表面脱附CO主要是以C=O断键形成;氢终止表面能够增强碳原子之间成键,提高C=O脱附的能垒,而氧终止表面作用相反,降低脱附能垒.     

IR spectra of benzaldehyde and its derivatives in different aggregate states

We have measured the IR Fourier-transform spectra of biologically active benzaldehyde and its derivatives in the gas and liquid phases. For compounds of this class, the role played by C=O, OH, and CH groups in intra- and intermolecular has been analyzed. We have revealed spectral features that characterize the participation of C=O groups of unsubstituted benzaldehyde molecules in the occurrence of intermolecular hydrogen bonds C=O...H-C with the formation of molecular dimers of different types. For 2-hydroxybenzaldehyde molecules, spectral data have been obtained that are indicative of the occurrence of intramolecular hydrogen bonds of the C=O...H-C type in solutions. In 2-methoxybenzaldehyde molecules, no intramolecular hydrogen bonds have been observed.     

The competition of neutrino energy loss due to the pair,photo-,plasma process at the late stages of stellar evolution

Based on the Weinberg-Salam theory,the competition of the Neutrino Energy Loss (NEL) rates due to the pair,photo- and plasma process are canvassed.The ratio factor C1,C2 and C3 which correspond the different contributions of the pair,photo- and plasma neutrino process to those of the total NEL rates are accurately taken into account.The ratio factors are very sensitive to the temperature and density.The ratio factor C2 always is lower than the ratio factor C1 and C3.The pair NEL process is the dominant contribution before the crossed point O(C1=C3=0.45) and the plasma NEL process will be the main dominant contribution after the crossed point O.With increasing temperature,the crossed point O will move to the direction of higher density.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

Solvent isotope effects on the hydration of alkaline cations: H/D secondary isotope effects on electrostatic interactions

We investigate H/D secondary isotope effects on the binding energies of water alkaline cation complexes, Alk⁺(X₂O)_n (X = H, D; Alk = Li, Na, K; n = 1 ? 4), using the any particle molecular orbital approach. Our results reveal that deuteration reduces water’s capacity to solvate alkaline cations. An explanation to this behaviour is proposed in terms of the observed changes in distances, partial charges, electrostatic potentials and polarisation induced by deuteration.