Intramolecular Hydrogen Bond and Internal Rotation of Aminogroup in Esters of Aminoacrylic Acids

The NMR ¹H and IR spectra of ethyl esters of two β-alkyl and β-aryl substituted of β-aminoacrylic acid have been measured. The results are evidence of the strong intramolecular hydrogen bond between amino group and carbonyl oxygen. The activation energy of about 20 kcal/mol was obtained for the internal rotation around C-N bond.     

旋转异构和键长变化对溶液中FTC分子光谱性质的影响

采用含时密度泛函理论结合极化连续模型计算了不同溶剂环境下FTC分子各旋转异构体的单光子吸收光谱. 结果显示在气态和溶剂中,各异构体的最大吸收波长均存在大约30 nm的差别. 在不同溶剂中,各异构体的能量次序和相应的玻尔兹曼统计分布几率发生了较大变化. 基于Hartee-Fock方法优化的结构,计算了玻尔兹曼统计平均吸收光谱,结果与实验符合得很好. 计算表明,对于所研究的分子体系,键长变化对分子的光谱性质有重要影响.     

An Investigation of 13C-NMR Spectra of Some Intramolecular Hydrogen Bonded and Non-Bonded Azo Dyes

The ¹³C-NMR spectra of the azo dyes which were synthesized by reacting substituted benzenediazonium chloride with derivatives of some phenol have been measured. The spectral data of these compounds were described considering intramolecular hydrogen bond and not. The chemical shift assignments were made regarding substituent effects.     

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。     

利用拉曼光谱分析冰Ih相的表面薄层的氢键结构

水是生活中一种最基本且最重要的物质,由于它的一些奇特性质和反常物性,得到了广泛的研究,而拉曼光谱是研究水分子结构的一种非常合适的方法,它通过获得分子的振动和转动信息来理解分子结构和分子间的相互作用。在常压下测量了-20～-190 ℃温度范围内冰Ih相的表面薄层的拉曼光谱,实验结果发现随温度降低,冰Ih相的O∶H范德瓦尔斯键向高波数方向移动,而O-H极性共价键向低波数方向移动;且拉曼频移与温度呈线性关系,通过对不同振动模式的斜率进行比较,判断其键长的伸缩变化关系,从而证明了冰Ih相密度随温度的减小而增大,采用氢键理论(结构)给予了解释。同时,发现在-150 ℃时,O-H键反对称伸缩振动模式和O∶H键振动模式的拉曼峰强发生了突变,这表明冰Ih相发生了相变--冰Ⅺ相(冰Ih的质子有序相)。     

乙基苯胺的转动光谱及分子结构

本文使用傅里叶变换微波谱仪研究了乙基苯胺类物质(邻乙基苯胺,间乙基苯胺,对乙基苯胺)的分子结构. 由于此类分子含氮原子(I¹⁴N=1),因此跃迁谱线中都呈现出核四级裂分. 通过比较实验测定得到的分子结构,可总结苯胺环上不同位置乙基的取代对氨基及分子整体结构的影响.     

Rotational Spectra of XeH and Its Isotopic Species

Frequencies of rotational transitions of XeH⁺ and its isotopic species were measured in the 1–5 THz region with a highprecision far-infrared spectrometer using a tunable radiation source. Measured frequencies were analyzed together with previous microwave and infrared measurements to refine mass-independent Dunham parameters.     

The Pure Rotational Spectra of AuCl and AuBr

The pure rotational spectra of AuCl and AuBr have been measured in the v = 0 and 1 (also for v = 2 for Au(35)Cl) vibrational states in the 5-22 GHz spectral region using a cavity pulsed-jet Fourier transform microwave spectrometer. The molecules were prepared by ablating Au metal in the presence of Cl(2) or Br(2) entrained in the Ar or Ne backing gas of the jet. The equilibrium internuclear distances r(e) have been determined along with estimates of the harmonic vibration frequencies and the dissociation energies. The ionic characters of the AuCl and AuBr bonds have been estimated from the halogen nuclear quadrupole-coupling constants to be i(c) approximately 38%. The gold nuclear quadrupole coupling constants change appreciably from AuF to AuCl to AuBr (including a sign change), indicating substantial differences in their electronic structures at Au; these variations could not be accounted for with a simple Townes-Dailey calculation. Copyright 2000 Academic Press.     

红外光谱吸收峰的剥离和模拟

本文运用计算机模拟技术对红外谱图进行吸收峰的剥离和模拟,用ＶＢ语言编制了吸收峰的剥离程序,并用实验谱图对所编程序进行了检测。得到了从谱图直接读峰和模拟所得峰位一致的的结果,且模拟谱可以得到更为详尽的吸收峰信息,如弱强度吸收峰及重叠峰等。验证了剥离程序的可靠性,为红外谱线的归属和化合物结构分析提供了更加丰富的信息。     

C77N+异构体的稳定性和电子光谱研究

用INDO系列方法对C78(C2V)的等电子体C77N+的所有21种可能异构体进行系统的理论研究.研究结果表明,最稳定异构体是由C78(C2V)沿Y方向椭球短轴所穿过的C(78)-C(73)键上的原子C(78)被N+取代所形成,椭球长轴附近的原子被取代所形成的异构体能量较低,取代位置附近易成为进一步反应的中心.用INDO/SCI方法计算了C77N+电子光谱,表明其吸收峰与C78(C2V)相比发生红移,对特征吸收峰进行了理论指认,讨论吸收峰红移的原因.     

C78O异构体的电子结构和光谱

为了模拟C78单加成物的加成位置和稳定性,并预测其光谱性质,用INDO系列方法对基于C2v-C78之上的C78O所有可能的34个异构体结构和电子光谱进行理论研究．结果表明,C78O的最稳定异构体是O加在位于C2v-C78短轴上的73,78-键上且形成环氧结构的6／6异构体,O的原子轨道对73,78-C78O中的HOMO能量降低起重要作用．讨论了电子跃迁性质和73,78-C78O电子光谱的长波吸收峰与母体相比发生蓝移的原因．     

微囊藻毒素-LR的特征红外光谱

利用傅里叶变换红外(FTIR)光谱仪研究了微囊藻毒素-LR在扫描范围4 000～600 cm-1的红外吸收光谱图,微囊藻毒素-LR分子构成中的主要官能团,如带有单一取代基的苯环、胍基、γ-羧基等特征红外吸收带在谱图上均得到了确认。     

Rotational Spectra of Conformers and Isotopomers of 1-Hydroxynaphthalene

The rotational spectra of cis- and trans-1-hydroxynaphthalene and trans-1-DO-naphthalene have been recorded between 6 and 18 GHz using a pulsed microwave spectrometer. Most of the transitions detected are a type; hyperfine splittings from the electric quadrupole interaction were observed for some transitions of the deuterated isotopomer. The frequencies were well modeled with an S-reduced asymmetric rotor Hamiltonian. The rotational constants were determined much more accurately than previously. In addition, the quartic centrifugal distortion parameters were determined for the first time. Their values were very small, consistent with the rigid framework of this aromatic molecule. Theoretical calculations were carried out to support the assignment of the two forms to the cis and trans conformers. These calculations suggested that the cis conformer is slightly nonplanar in its equilibrium configuration, a property which is not inconsistent with its rotational constants. Copyright 1999 Academic Press.     

3-三苯基锗基-1,1-二苯基-1-丙烯及其同系物的拉曼光谱和红外光谱

我们合成了一类多苯基取代的烯丙基锗烷类化合物,并测量了这三种化合物的拉曼光谱和红外光谱。经光谱分析,指认了主要波数所对应的分子振动。在这三种化合物的拉曼光谱中,Ge-Ph均在1000cm-1附近出现非常强的振动峰;烯丙基中的C=C键在1615 cm-1和1595 cm-1附近出现强的振动峰;在1585 cm-1附近出现芳香环的多重振动峰;在3050 cm-1(m)1、025 cm-1(m)、615 cm-1(m)附近出现芳香环的C-H伸缩振动,C-H面内弯曲振动和C-H面外弯曲振动峰;与饱和碳原子相连接的Ge-C振动峰分别出现在595 cm-1、592 cm-1和597 cm-1。在红外光谱中,这类化合物的Ge-C振动和饱和Ge-C振动较为明显,分别出现在1090 cm-1(s)附近和625 cm-1~577 cm-1(w)之间。     

Stickiness of the Hydrogen Bond

The dielectric response of bulk water follows laws of continuum electrostatics, a scheme often extrapolated without justification to treat confined interfacial water, where the Debye polarization ansatz breaks down and discrete effects matter. Reconciling the discrete behavior with the continuum equations requires a conceptual leap, all the more so when assessing the electrostatic impact of exclusion of individual water molecules. This work takes up the challenge and identifies the nanoscale stickiness of a preformed water‐embedded hydrogen bond as phenomena not encompassed by continuum laws but quantitatively predictable when adopting a nanoscale theory of dielectric response holding down to molecular dimensions. Nanoscale stickiness is known to drive basic cellular events and has been measured using a molecular force probe but its physical underpinnings and computation have been lacking so far. The findings reported may impact molecular design in bio‐nanotechnology and shed light on standing challenges in biophysics, especially on the protein folding problem, where organized compaction of the protein chain following nucleating intramolecular hydrogen bonding demands explanation.     

The Influence of Intramolecular Coupling between v(XH) and v(XH…Y) Modes on the IR Absorption Spectra of Hydrogen Bonded Species XH…Y

By modifying the simple Morse oscillator model usually used for describing the vibrational motion of a linear XH…Y complex a more realistic model is proposed, which is in better agreement with experimental results. The potential energy surface is derived by fitting the bond length, the dissociation energy of the H-bond, the bond length shortening, and the normal frequency of the v(XH) vibration to their observed values. From the resulting values of the transition matrix elements between low excited v(XH) and high excited v(XH…Y) quantum states it is shown, that for explaining the smoothness of the IR absorption bands the intramolecular coupling between v(XH) and v(XH…Y) stretching modes of vibration should be taken into account.     

新型电荷转移多金属氧酸盐的合成和红外光谱研究

以4种道森结构的杂多酸和3种芳香杂环化合物为原料合成了11种新型电荷转移多金属氧酸盐，研究了它们的红外光谱。结果表明：杂多酸形成电荷转移盐后，杂多阴离子的结构略有畸变但仍保持道森结构；有机给体和杂多阴离子之间存在电荷转移相互作用。