1,4-苯二硫醇的表面增强拉曼光谱和激发态的密度泛函理论研究

利用密度泛函理论(density functional theory,DFT)在B3LYP/6-311+g(d)(C,H,S)和Lanl2dz(Ag、Au)基组下对1,4-苯二硫醇分子及其复合物进行了结构优化和频率计算,得到了分子及其复合物稳定的化学构型和拉曼光谱。优化后的1,4-苯二硫醇分子的S—H键和苯环所在平面夹角为20.2°,分子非平面结构。模拟了金银团簇在苯硫醇分子表面的吸附行为,得到了金团簇和银团簇在分子表面的吸附方式,即,金团簇以接近平行的方向吸附于苯硫酚分子的表面而银团簇则以几乎垂直的方向吸附于分子表面。此外,还分析了静态极化率数值变化和自然键轨道(natural bond orbital,NBO)布局分析得到的电荷分布对拉曼光谱的强度变化的影响。复合物1,4-BDT-Au2,1,4-BDT-Ag2和三明治结构的Ag2-1,4-BDT-Au2拉曼光谱谱峰强度与静态极化率数值变化有很好的吻合。采用含时密度泛函理论(time dependent density functional theory,TDDFT)对Ag2-1,4-BDT-Au2复合物进行了激发态的分析计算,通过模拟吸收光谱和计算轨道跃迁单激发态,分析计算了三明治结构的电荷转移激发态,利用可视化的电荷转移,研究了表面增强拉曼(surface enhanced Raman scattering,SERS)化学增强机理。     

糠醛分子的拉曼光谱与红外光谱研究

本文报道了糠醛分子的正常拉曼谱(NRS)和红外吸收光谱(IRS),同时我们运用DFT(density functional theory,密度泛函理论)计算了FUR(Furfural)分子的振动光谱。理论结果很好的符合了实验数值。通过理论和实验数据的比较分析,对糠醛分子的特征振动模式进行了归属。     

对巯基苯胺分子表面增强拉曼光谱的密度泛函理论研究

采用密度泛函理论(density functional theory,DFT),在B3LYP/6-31++-G** (C,H,N,S)/LANL2DZ(Ag)水平上,对对巯基苯胺(p-aminothiophenol,PATP)分子进行了几何结构优化,计算了 PATP的常规拉曼散射(normal Raman scatte...     

6-巯基-5-三唑并[4,3-b]-s-四嗪(MTT）的密度泛函理论研究

采用密度泛函理论（Density functional theory，DFT），在B3LYP/6-31g(d) (C,H,N,S)，Ag原子采用LanL2d赝势基组水平上对甲醛（HCHO）与4-氨基-5肼基-3-巯基-1，2，4-三唑(4-amino-5-hydrazino-3-mercapto-1,2,4-triazole，AHMT)衍生化反应生的成产物6-巯基-5-三唑并[4,3-b]-s-四嗪（6-mercapto-5-triazolo[4,3-b]-s-tetrazine，MTT）及其银配合物进行结构优化，优化结果表明MTT的结构是一个近平面结构。通过对频率计算，获得MTT分子及其银配合物的拉曼光谱，对400-1800 cm-1波段内的拉曼光谱特征峰进行了指认。同时讨论了MTT分子的表面静电势，分析可能发生化学反应的位点。并采用含时密度泛函理论（Time Dependent density functional theory，TDDFT）对MTT分子与Ag3配合物的激发态进行了计算分析，并使用电荷转移光谱对Ag配合物与MTT之间电荷转移关系进行了研究。该研究对MTT分子的光谱测定和电子性质提供了理论基础。     

基于DFT的间羟基苯甲酸分子表面增强拉曼光谱研究

本文研究了间羟基苯甲酸(m-hydroxybenzoic acid,MHBA)的常规拉曼散射(normal Raman scattering,NRS)光谱及其吸附在Ag纳米颗粒上的表面增强拉曼散射(surface-enhanced Raman scattering,SERS)光谱。采用密度泛函理论(density functional theory,DFT),在B3LYP/6-31+G**(C、H、O)/LANL2DZ(Ag)水平上,对MHBA分子进行了几何结构优化,在此基础上计算了MHBA分子的NRS光谱以及其吸附在Ag纳米颗粒上两种不同吸附构型下的SERS光谱,并和实验值进行比较。结果表明,间羟基苯甲酸分子通过羧基与羟基共同吸附构型的计算结果比该分子通过羧基吸附构型的计算结果更符合实验值。最后,利用GaussView可视化软件对其振动模式进行了全面归属。     

葡萄糖分子的表面增强拉曼光谱研究

本文以密度泛函理论(density functional theory, 简称DFT)采用B3LYP混合泛函和6-31++G(d, p)基函数组计算的葡萄糖的分子振动光谱为根据, 首次对葡萄糖分子的常规拉曼光谱(NRS)进行了详细的指认, 并对葡萄糖分子的振动模式进行了归属。在以4-巯基吡啶为桥联剂分子修饰的银镜衬底上, 观测到葡萄糖分子的表面增强拉曼散射(SERS), 并对葡萄糖分子在银表面的吸附状态进行了分析。     

杀草强分子的拉曼光谱的密度泛函理论研究

采用B3LYP杂化泛函,6-31++g(d,p)基组,对杀草强分子的结构进行了优化;通过频率计算,获得了杀草强分子的拉曼光谱,并利用势能函数分布(PED)对拉曼光谱进行了指认;结合SERS光谱推测了杀草强和增强基底之间的吸附方式。     

糠醛分子表面增强拉曼光谱的密度泛函理论研究

采用密度泛函理论(density functional theory,DFT),在B3LYP/6-31+G**(C,H,O)/LANL2DZ(Ag)水平上,对糠醛(furfural,FUR)分子进行了几何结构优化,并计算了FUR分子的常规拉曼散射(normal Raman scattering,NRS)光谱和FUR与Ag原子以及Ag2和Ag4团簇吸附的表面增强拉曼散射(surface-enhanced Raman scattering,SERS)光谱。结果表明,理论值与已有的实验值符合得较好,采用FUR-Ag4吸附构型的计算结果比FUR-Ag和FUR-Ag2吸附构型的计算结果更符合已有实验值。最后,通过Gauss View可视化软件,对FUR分子的振动频率进行了更为全面地归属。通过FUR分子SERS与NRS的比较,可得出FUR分子与Ag原子发生了相互作用,且被吸附的糠醛分子的杂五环是与银表面垂直的。     

环草酰胺表面增强拉曼光谱密度泛函理论研究

根据密度泛函理论(DFT),在B3LYP方法下,Ag原子使用LANL2DZ赝式基组,C,H,N,O和Cl原子使用6-31++G(d,p)基组,优化并计算了环草酰胺和环草酰胺银配合物的拉曼光谱,并利用密度泛函理论对环草酰胺分子拉曼光谱及其SERS进行详细归属,为食品和产品中吩噻嗪残留的定性、定量测定提供理论依据。计算结果说明连接Ag原子越多,增强效果越明显。     

农药辛硫磷的密度泛函理论计算及拉曼光谱分析

辛硫磷(Phoxim)是一种高效、低毒、低残留有机磷杀虫剂,能抑制胆碱酯酶活性.辛硫磷的分子构型用Gauss View 5.0构造,理论计算采用密度泛函理论(density functional theory, DFT)的B3LYP/6-31+G(d, p)基组计算农药辛硫磷的拉曼光谱,实验上则采用分辨率为2 cm~(-1)的三级显微拉曼光谱检测仪对辛硫磷-甲醇溶液,辛硫磷乳油进行拉曼光谱检测.将理论拉曼光谱与实验拉曼光谱进行对比,其中有几个对应比较一致的拉曼光谱峰分别位于667, 745, 997, 1025, 1298, 1588 cm~(-1)处.首次报道了辛硫磷的拉曼光谱,同时对辛硫磷在600～1800 cm~(-1)区间的拉曼光谱进行了指认,指出了其在相应的频移位置产生较强拉曼光谱的分子振荡模式.     

反式乙烯基联吡啶表面增强拉曼光谱的密度泛函理论研究

反式乙烯基联吡啶具有极好的拉曼散射信号,经常用做探针分子.利用密度泛函理论(DFT)理论,采用BP86,BPw91和B3LYP等方法,Ag原子使用赝式基组,H,C,N等原子使用6-31+ +G(d,p)基组,计算了反式乙烯基联吡啶与银配合物(t-BPE-Ag)的Raman光谱,并且利用势能分布(PED)计算结果对t-BPE分子Raman光谱和SERS谱进行了详细的归属,DFT理论得到结果说明根据DFT理论计算t-BPE-Ag配合物得到的Raman光谱与实验SERS谱基本一致,并且键连Ag原子越多,与实验值会更接近,t-BPE-Ag配合物HOMO与LUMO的能级差估计在449～912 nm范围内.     

2-巯基噻二唑的拉曼、红外光谱、DFT计算和简正振动分析

采用B3LYP混合泛函和6-311G基函数组,并对重原子和轻原子使用离散函数和极化函数,利用密度泛函理论计算了2-巯基噻二唑的分子振动频率。实验测量了2-巯基噻二唑分子的拉曼、红外光谱,以实验频率为标准对分子内力场进行了标度,采用简正振动分析方法得到了各振动模的势能分布,从而对该分子的振动频率归属做出了全面指认。     

2-巯基-5-甲基-1, 3, 4-噻二唑分子的拉曼、红外光谱和简正振动分析

实验测量了2-巯基-5-甲基-1, 3, 4-噻二唑分子的拉曼和红外光谱, 采用B3LYP混合泛函和6-31+G(d, p)基函数组, 计算了该分子的最稳定构型和振动频率。以实验频率为标准采用简正振动分析方法得到了该分子各振动频率的势能分布, 从而对其振动频率归属做出了全面地指认。     

Vibrational spectroscopy investigation using density functional theory on 7‐chloro‐3‐methyl‐2H‐1,2,4‐ benzothiadiazine 1,1‐dioxide

The solid phase Fourier transform infrared (FTIR) and Fourier transform (FT) Raman spectral analysis of 7‐chloro‐3‐methyl‐2H‐1,2,4‐benzothiadiazine 1,1‐dioxide (diazoxide), an antihypertensive agent was carried out along with density functional computations. The optimized geometry, wavenumber and intensity of the vibrational bands of diazoxide were obtained by DFT‐B3LYP level of theory with complete relaxation in the potential energy surface using 6‐31G(d,p) basis set. A complete vibrational assignment aided by the theoretical harmonic frequency analysis has been proposed. The harmonic vibrational wavenumbers calculated have been compared with experimental FTIR and FT Raman spectra. The observed and the calculated wavenumbers are found to be in good agreement. The experimental spectra coincide satisfactorily with those of calculated spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Adsorption of 1,2,4‐triazole on a silver electrode: surface‐enhanced Raman spectroscopy and density functional theory studies

The pH‐dependent surface‐enhanced Raman scattering (SERS) of 1,2,4‐triazole adsorbed on silver electrode and normal Raman (NR) spectra of this compound in the aqueous solutions were investigated. The observed bands in the NR and SERS spectra were assigned with the help of density functional theory calculations for model molecules in the neutral, anionic, and cationic forms and their complexes with silver. The Raman wavenumbers and intensities were computed at the optimized molecular geometry. Vibrational assignments of the SERS and NR spectra are provided by calculated potential energy distributions. The combination of experimental SERS results and density functional theory calculations provide an insight into the molecular structure of adlayers formed by 1,2,4‐triazole on a silver surface at varying pH values and enable the determination of molecular orientation with respect to the surface. Copyright © 2012 John Wiley & Sons, Ltd.     

醛类分子的拉曼光谱研究

应用便携式拉曼光谱仪,采集了四种醛类分子(GnH2nO,n=1,2,3,4)的拉曼光谱,并通过量子化学中密度泛函理论(DFT)对四种醛类分子进行了分子模型构建和理论拉曼光谱模拟计算.通过实验拉曼光谱和DFT模拟计算结果的对比,对四种醛类分子的特征振动峰进行了指认.同时对四种醛类分子的实验光谱进行了分析比较.应用便携式拉...     

三碘甲状腺素团簇结构与光谱性质的密度泛函理论研究

我们利用密度泛函理论(DFT)，在B3LYP/Lan12mb基组水平上，得到了三碘甲状腺素团簇的几何和电子结构.在此基础上，利用含时密度泛函理论(TDDFT)，使用相同的基组和采用极化连续介质模型(PCM)，对其溶剂效应下的吸收光谱进行研究．研究结果表明，优化所得三碘甲状腺素团簇的对称性为C₁;在基态稳定结构基础上，研究了该分子的红外和拉曼分子振动谱特性，同时研究了其输运性质，即三碘甲状腺素团簇为p型输运材料;通过含时密度泛函理论，在优化好的基态结构基础上，又计算了它的溶剂效应，进一步得出该分子在水溶剂中的吸收光谱特性.     

Vibrational and electronic spectral analysis of 2,3-pyrazinedicarboxylic acid: A combined experimental and theoretical study

Fourier transform infrared and Raman spectra of 2,3-pyrazinedicarboxylic acid were recorded and analyzed using density functional theory. The complete assignments of the anharmonic vibrational modes have been performed based on potential energy distribution. The anharmonic frequencies were computed using vibrational second-order perturbation theory as well as vibrational self-consistent field and correlation corrected vibrational self-consistent field methods. Mode–mode coupling strength is also estimated using two-mode representation of quartic force field approximation. The intra- and intermolecular interactions were also studied in the dimer and trimer forms of the title molecule. The ultraviolet–visible absorption spectra in ethanol, methanol, and acetonitrile solvents were recorded and analyzed using time-dependent density functional theory involving the polarization continuum model. The observed and calculated results are well comparable. Molecular electrostatic potential and the highest occupied and the lowest unoccupied molecular orbital analyses are also reported.     

异硫氰基-孔雀石绿的拉曼光谱计算及分析

异硫氰基-孔雀石绿(malachite green isothiocyanate,MGITC)是应用于细胞探测,生物组织成分分析和细胞成像等方面的拉曼探针分子.本文首先给出了MGITC分子的结构图,并用密度泛函(DFT)算法对其进行了空间结构优化;然后分别用Hartree-Foek(HF)和MP2两种算法基于STO-3G基组计算了它的拉曼光谱与红外光谱,给出光谱强度图;并对比了两种算法的拉曼光谱图和其实验光谱图,结果显示了很好的一致性;本文还给了MGITC分子中的各个原子键长,键角等空间结构参数;并对MGITC分子在550～4 200cm-1区间的振动谱做了指认.这些工作将促进MGITC作为探针分子在生物学领域的应用.     

Vibrational spectroscopy investigation using ab initio and density functional theory on flucytosine

The FT Raman and FTIR spectra of flucytosine were recorded in the region 3500–100 cm⁻¹ and 4000–400 cm⁻¹, respectively. The optimized geometry, wavenumber and intensity of the vibrational bands of flucytosine were obtained by ab initio and density functional theory (DFT) levels with complete relaxation in the potential energy surface using the 6‐31G(d,p) and 6‐311G(d,p) basis sets. A complete vibrational assignment aided by the theoretical harmonic frequency analysis is proposed. The harmonic vibrational wavenumbers calculated are compared with experimental FTIR and FT Raman spectra. The observed and the calculated wavenumbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar‐type spectrograms. Copyright © 2007 John Wiley & Sons, Ltd.