四甲基脲与水二元混合体系的拉曼光谱研究

密度泛函B3LYP方法在6-311G*基组水平对四甲基脲(TMU)气态的几何构型进行全面优化,计算了最优构型的拉曼光谱,并与实验得到的拉曼光谱进行比较,对TMU的各拉曼谱带进行归属。实验测得了TMU与水不同体积比二元混合体系的拉曼光谱,得到了TMU分子的特征拉曼谱线在不同浓度下的频移情况,受氢键和缔合水分子空间位阻的共同作用,在H2O/TMU体积比小于2时,TMU羧基伸缩振动频率向低波数的变化与体积比成线性关系,当体积比大于2时,其振动频率为定值1585cm-1,其它拉曼带的频率受到溶剂的非专一化作用而随溶液中水的增加变化不大。     

表面增强拉曼光谱快速检测蜂蜜中的金霉素残留

利用表面增强拉曼光谱(SERS)技术对蜂蜜中的金霉素(CTC)残留进行了快速、无损检测.以自制的金纳米粒子作金霉素的拉曼增强基底,对金纳米粒子与金霉素混合体积比及混合时间进行了讨论与优化,检测了不同浓度梯度的金霉素标准溶液,绘制了特征峰处浓度-拉曼信号强度的线性方程,对蜂蜜进行前处理后,运用加标回收法考察其回收率.结果表明,金霉素溶液在1450 cm-1处的特征峰可以作为蜂蜜中金霉素残留量检测的特征峰,金纳米基底和金霉素标准液的最佳混合体积比为1∶1,最佳混合时间为1 min.金霉素的浓度(X)在10~250 mg/L范围内与其在1450 cm-1处的SERS特征峰强度(Y)有着良好的线性关系,线性方程为Y=1×10-4X+0.0110(R2=0.9948).检测实际蜂蜜样品中金霉素含量的加标回收率均在80%~120%之间.该检测方法操作简单、快捷、准确度高,为检测食品中抗生素残留提供了新的思路和方法.     

三元水溶液体系中氢键作用与分子结构的拉曼光谱研究

采用拉曼光谱研究了水-乙腈-二甲基亚砜三元水溶液体系中氢键作用对分子结构的影响.结果表明,在三元水溶液中乙腈C≡N键的电子云向碳原子发生偏移,二甲基亚砜中S=O双键的电子云向硫原子发生偏移;在三元体系中乙腈和二甲基亚砜与水形成氢键时存在明显的竞争关系,出现乙腈分子和二甲基亚砜分子共用1个水分子形成复合物的情况,并且随着水含量的增加,共用水分子的情况逐渐消失.     

近红外光谱用于低温水结构的分析

采用近红外光谱分析并结合拉曼光谱和分子动力学模拟研究了二甲基亚砜(DMSO)-水混合物中水在低温时的结构,对DMSO降低水冰点的机理进行了讨论.通过对不同DMSO含量混合物的近红外和拉曼光谱分析,发现了DMSO与水相互作用的光谱信息,表明DMSO与水在混合物中主要以摩尔比1∶2和2∶1的氢键结构(DW2和D2W)的形式存在,结构形式主要取决于DMSO和水在混合物中的比例.通过对水和30%(摩尔分数)DMSO-水混合物的温控近红外光谱分析,发现DW2结构抑制四面体水结构的形成是混合物冰点降低的主要原因.采用分子动力学模拟对DMSO-水混合物体系进行的模拟进一步证明了结论的可靠性.     

锂硫电池中碳酸乙烯酯与硫簇反应拉曼光谱的理论研究

通过密度泛函理论(DFT)计算了锂硫电池中多硫阴离子(S2-n)和碳酸乙烯酯(EC)的2种反应机理,并对其反应物和主要产物的拉曼光谱进行了理论分析.计算结果表明,2种反应路径中,S2-n进攻EC分子烷基碳所需活化能和Gibbs自由能均较低.多硫基团有很强的拉曼特征谱峰,与EC分子相关的部分拉曼谱亦发生显著变化.锂离子的存在影响反应产物的结构和拉曼光谱.密度泛函理论计算提供了锂硫电池中锂、多硫阴离子和电解液反应前后的结构变化和反应信息.     

三(4-硝基苯基)甲烷衍生物的结构和振动光谱的理论研究（英文）

用密度泛函理论优化了三苯甲烷(1)和一系列三(4-硝基苯基)甲烷衍生物2,3和4的几何结构,并计算了其红外光谱和拉曼光谱;通过与实验光谱的对比,对实验光谱中的谱峰进行了指认,并从理论上纠正了部分对3和4红外光谱谱峰不合适的实验指认;同时预测了2,3和4的拉曼光谱.结果表明,几种化合物的振动光谱计算结果与相应的实验结果吻合良好;且化合物2,3和4的拉曼光谱具有相似性.     

高压下D,L-扁桃酸结构相变的拉曼光谱研究

采用金刚石对顶砧高压装置,在室温下对D,L-扁桃酸(C8H8O3)进行了原位高压拉曼光谱研究,实验最高压力为2.2 GPa.结果表明,原来的一些拉曼峰在0.6 GPa左右突然消失或者劈裂,并同时出现了一些新的拉曼峰.通过进一步分析D,L-扁桃酸的拉曼频率随压力的变化,发现许多拉曼峰的移动在0.6 GPa时都出现了拐点.D,L-扁桃酸在0.6 GPa发生了由正交相(Pbca)到单斜相(P21/c)的压致结构相变.通过分析相变前后晶体结构及拉曼振动模式的变化,认为此压致结构相变是由高压下分子的密堆积效应和氢键结构的重新排列导致.完全卸压至常压后,卸压拉曼光谱与常压拉曼光谱一致,表明此压致相变可逆.     

激光共焦显微拉曼光谱技术对手印中海洛因及其稀释剂的检测研究

利用激光共焦显微拉曼光谱技术对汗潜手印和油潜手印中的海洛因、烟酰胺、碳酸钠、葡萄糖、淀粉、蔗糖、滑石粉进行了检测,并对主要拉曼特征峰所对应的分子振动基团进行了识别,在此基础上,对手印中的混合毒品进行分析检测。实验结果表明,在不破坏手印的情况下,激光共焦显微拉曼光谱技术实现了对手印中海洛因、烟酰胺、碳酸钠、葡萄糖、淀粉、蔗糖、滑石粉的快速检测,对手印中混合毒品样品中的海洛因成分能够有效的识别,手印中的油脂不影响以上各物质的检测识别,通过显微红外光谱技术对试验结果的准确性进行了确认,研究结果将为相关涉毒案件的侦破提供有力的技术支持。     

超支化聚酯修饰多壁碳纳米管

将碳纳米管先用V(H2SO4)∶V(HNO3)=3∶1混合溶液进行处理,再用V(H2SO4)∶V(H2O2=4∶1的混合溶液进一步酸化,制得含有羧基的碳纳米管。将羧基化碳纳米管与二氯亚砜反应使碳纳米管连接酰氯基团,利用酰氯基团与超支化聚酯上的羟基反应,将超支化聚酯接到碳纳米管的表面上,实现了碳纳米管的表面修饰。利用红外光谱、拉曼光谱、透射电镜观察分析测试结果表明,超支化聚酯以共价键形式连接到碳纳米管的表面。热失重分析结果表明,修饰密度为每321个C原子连接1个H20分子,每842个C原子上连接1个H40分子。修饰后的碳纳米管在有机溶剂中的溶解性能明显提高。     

DNA碱基激光拉曼光谱检测方法的研究

以激光拉曼光谱仪采集腺嘌呤(A)、鸟嘌呤(G)、胞嘧啶(C)、胸腺嘧啶(T)的拉曼光谱图,分析了各碱基谱峰归属,并依据归属结果检测混合碱基组成。结果显示:4种碱基的特征峰集中在175～1 800cm~(-1)。相同积分时间和激光功率条件下,该波段内嘌呤碱基的激光拉曼光谱峰高于嘧啶碱基的谱峰。腺嘌呤、鸟嘌呤、胞嘧啶、胸腺嘧啶分别在723、648、791、1 368 cm~(-1)处的谱峰最强,利用这些特征峰能在2min内鉴别出混合碱基中的各碱基。     

Vibrational spectroscopic force field studies of dimethyl sulfoxide and hexakis(dimethyl sulfoxide)scandium(III) iodide, and crystal and solution structure of the hexakis(dimethyl sulfoxide)scandium(III) ion

Hexakis(dimethyl sulfoxide)scandium(III) iodide, [Sc(OS(CH(3))(2))(6)]I(3) contains centrosymmetric hexasolvated scandium(III) ions with an Sc-O bond distance of 2.069(3) angstroms. EXAFS spectra yield a mean Sc-O bond distance of 2.09(1) angstroms for solvated scandium(III) ions in dimethyl sulfoxide solution, consistent with six-coordination. Raman and infrared absorption spectra have been recorded, also of the deuterated compound, and analysed by means of normal coordinate methods, together with spectra of dimethyl sulfoxide. The effects on the vibrational spectra of the weak intermolecular C-H...O interactions and of the dipole-dipole interactions in liquid dimethyl sulfoxide have been evaluated, in particular for the S-O stretching mode. The strong Raman band at 1043.6 cm(-1) and the intense IR absorption at 1062.6 cm(-1) have been assigned as the S-O stretching frequencies of the dominating species in liquid dimethyl sulfoxide, evaluated as centrosymmetric dimers with antiparallel polar S-O groups. The shifts of vibrational frequencies and force constants for coordinated dimethyl sulfoxide ligands in hexasolvated trivalent metal ion complexes are discussed. Hexasolvated scandium(iii) ions are found in dimethyl sulfoxide solution and in [Sc(OSMe(2))(6)]I(3). The iodide ion-dipole attraction shifts the methyl group C-H stretching frequency for (S-)C-H...I(-) more than for the intermolecular (S-)C-H...O interactions in liquid dimethyl sulfoxide.     

Thermodynamic Study of Poly(vinyl pyrrolidone) in Water/Dimethyl Sulfoxide Solutions by Viscometry

In this work, the intrinsic viscosities of poly(vinyl pyrrolidone) with a molar mass of 58?kg?mol^?1 were measured in water?Cdimethyl sulfoxide solutions at temperatures from (298.15 to 318.15)?K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer?Csolvent interaction parameter and second osmotic virial coefficient) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that mixtures of water/dimethyl sulfoxide become poorer solvents for poly(vinyl pyrrolidone) as the temperature is increased. Also, the thermodynamic parameters indicate that water/dimethyl sulfoxide mixtures become better solvents for poly(vinyl pyrrolidone) by increasing the volume fractions of dimethyl sulfoxide.     

Separation of purines and pyrimidines by normal-phase high-performance liquid chromatography using dimethyl sulfoxide in binary and ternary eluents

Chromatographic systems with a silica sorbent and mobile phases containing dimethyl sulfoxide have been studied. It has been established that the substitution of isopropanol by dimethyl sulfoxide in binary eluents results in a specific selectivity of the chromatographic system and shows an improvement of the peak shape for the solutes under study. When mobile phases consisting of hexane, isopropanol and dimethyl sulfoxide (solvents with a limited mutual solubility) are used, changes in retention characteristics and peak symmetry are caused by a transition from adsorption to partition sorption mechanism. The stationary liquid phase is generated dynamically in the pores of silica, even in the mobile phases not saturated with a polar component. If the phase ratio of the column reaches 0.1, partition dominates over adsorption and such mixed partition-adsorption (MPA) systems show very good peak symmetry for the solutes under study. The investigation has shown that dimethyl sulfoxide-containing MPA systems are applicable in analytical practice.     

Elimination of oxidative degradation during the per-O-methylation of carbohydrates

The possible oxidative degradation mechanism occurring during the per-O-methylation of carbohydrates in dimethyl sulfoxide with methyl iodide in the presence of base is described. Evidence is presented that this process occurs only under anhydrous conditions when there is a long reaction time between the carbohydrate dissolved in dimethyl sulfoxide and methyl iodide, followed by reaction with the base. Under these specific conditions, the oxidative degradation of alditols, and cyclic carbohydrates, with and without a free hemiacetal group, is observed. The reaction between carbohydrate and methyl iodide in dimethyl sulfoxide can result in a complete oxidative degradation depending on the type of carbohydrate and the time of reaction. The oxidative degradation can be accelerated by replacing methyl iodide with dimethyl sulfate. Mass spectrometric identification of the degradation products of d-glucitol indicates simultaneous oxidation processes at all the hydroxyl groups, with site dependent rates of their reactivity. This oxidative process is not a characteristic of the methylation of carbohydrates in dimethyl sulfoxide with methyl iodide in the presence of solid sodium hydroxide and can be totally avoided by treating the carbohydrate with powdered sodium hydroxide before introduction of methyl iodide under nonanhydrous conditions, or by adding a trace of water in dimethyl sulfoxide before methyl iodide, or by using N,N-dimethylacetamide as the solvent. The degradation of the per-O-methylated carbohydrates in the liquid-liquid extraction process is also taken into account, and it is found that the degradation process can be avoid by neutralization of the base before extraction, by using benzene or tetrachloromethane as extraction solvent, and by drying the final organic extract.     

Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography

Static headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS-gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents.     

Synthesis of polymolybdenophenylsiloxane

Polymolybdenophenylsiloxane containing Mo(V) atoms and preserving the Si : Mo ratio equal to that in the starting mixture was prepared by the reaction of molybdenum(V) oxychloride dimethyl sulfoxide crystal solvate with sodium polyphenylsiliconate in the presence of dimethyl sulfoxide. The influence of the reaction conditions on the nature and yields of products was examined. Experiments on thermal oxidative degradation of polymolybdenophenylsiloxane showed that it is more stable compared to the previously studied polymetalloorganosiloxanes containing various d elements with the stoichiometric Si : metal ratio.     

Calculation of the deuteron quadrupole relaxation rate in a mixture of water and dimethyl sulfoxide

An approach is presented that allows NMR relaxation rates to be determined for a complex mixture, and it is applied to a dimethyl sulfoxide/water solution. This approach is novel for such systems, having only been used for simple systems such as atomic liquids or atomic ions in liquids until now. It involves use of a predetermined, quantum mechanical, multidimensional property surface in a simulation. The results are used in conjunction with the simulated rotational correlation time to calculate the deuteron quadrupole coupling constant (DQCC), in an analogous approach to the one used by experimentalists, and to examine the surprising experimental findings for the composition dependence of the DQCC in the dimethyl sulfoxide/water mixture. Experiments have suggested that the DQCC for a mixture of 5% dimethyl sulfoxide in water is close to the DQCC of ice, whereas its value increases to a value close to the gas value with further dilution.(1) The results are further critically analyzed using combinations of different experimental and theoretical results from the literature.     

Water soluble,conjugated main chain azo polymer: Synthesis and characterization

The monomer 2,5-diaminobenzenesulfonic acid has been polymerized to a high molecular weight, conjugated main chain azo polymer. The presence of the azo group in the polymer was confirmed using Raman spectroscopy. The polymer is highly soluble in water over a wide pH range. It is also soluble in common polar organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone.     

非离子聚(N-乙烯基-2-吡咯烷酮)凝胶在线型聚(丙烯酸)溶液中的溶胀特性

研究了在线型聚 (丙烯酸 ) (PAA)溶液中链长、pH、离子强度和水 /二甲亚砜混合溶剂组成对非离子聚 (N-乙烯基 - 2 -吡咯烷酮 ) (PVP)水凝胶溶胀特性的影响 .发现聚酸浓度的变化引起凝胶显著的体积相变 ,这是因为凝胶和聚合物通过氢键形成了大分子间凝胶 -聚合物复合物 .凝胶的溶胀特性取决于聚酸的链长而不是离子强度 .随着pH值和水 /二甲亚砜混合溶剂组成的变化 ,凝胶的溶胀率 (SR)发生变化