Surface Catalytic Coupling Reactions and SERS Spectra of Thiourea, Adenine and Adenine Derivatives on Silver Nanostructures: A DFT Study

表面催化偶联反应是指一些芳香胺类分子或具有共轭结构的胺类分子可以在银、金等金属表面发生偶联反应生成偶氮化合物。表面增强拉曼光谱（SERS）由于具有很高的检测灵敏度，可以获得高质量的表面吸附分子的拉曼信号，因此被广泛用于研究金属纳米结构表面吸附分子的物理化学行为。为了进一步探究和丰富表面催化偶联反应理论，我们采用密度泛函理论计算分析了硫脲、腺嘌呤及其衍生物在银纳米结构表面发生催化偶联反应的可行性，以及其可能的表面存在形式。 （1）计算硫脲分子在银表面发生偶联反应的机理以及中间体的分子光谱。我们认为硫脲在银表面光辐射下容易生成联二硫脲，然后进一步被氧化成芳香类分子3,6-二巯基-1,2,4,5-...Some aromatic amines and conjugate amines can undergo the surface catalytic coupling reactions to selectively produce the azo species on some metal nanostructure surfaces (e.g. Ag and Au). Surface-enhanced Raman spectroscopy (SERS) with high sensitivity and high-quality Raman signals is applied widely in investigating the physical chemical behaviors of adsorption molecules on metal surfaces. To fu...学位：理学硕士院系专业：化学化工学院_物理化学(含化学物理)学号：2052011115162

Density Functional Theory Calculations of the Influence of Weak Hydrogen Bonding Interactions on the Raman Spectra of Thiourea in Aqueous Solution

将拉曼光谱和密度泛函理论(dfT)计算结合能够把拉曼谱峰和分子结构及分子间氢键作用之间的变化联系起来,反映分子周围的结构信息.本文通过理论计算水分子和硫脲形成复合物的拉曼光谱,并结合实验报道的拉曼光谱,探究硫脲基频对分子局域结构的依赖性.通过轨道分析,发现水分子的氢键作用可以引起硫脲的前线轨道对易,这将影响到硫脲的拉曼光谱性质.最后计算也表明在中性水溶液中由于大的正gIbbS自由能变,硫脲不易发生异构转变.Raman spectroscopy combined with density functional theory(DFT) calculations provides information at the molecular level to understand weak intermolecular interactions relevant to molecular structures.In this work, the influence of the fundamental properties of thiourea on the Raman spectra of thioureawater complexes was investigated using DFT calculations.The results showed that hydrogen bond interactions can change the order of the frontier orbitals and directly influence the Raman spectra of thiourea.In addition,the keto-enol tautomerization of thiourea cannot occur in neutral aqueous solution because of the large positive Gibbs free energy change.国家自然科学基金(21373172;21321062)资助项目~

Reaction of p-Chloronitrobenzene Adsorbed on Silver Nanoparticles

Corresponding author. Email: [email protected]; Tel: +86-592-2189023[中文文摘]表面增强拉曼光谱(SERS)具有极高的检测灵敏度,通过检测吸附分子的SERS信号,可以获得表面吸附分子的结构以及可能发生的反应.在拉曼激发光源的辐射下,在碱性溶液中,银纳米粒子表面吸附的对氯硝基苯(PCNB)的SERS光谱与其固体的常规拉曼光谱相比,出现异常SERS谱.通过采用密度泛函理论(DFT)计算,对PCNB以及可能的偶联产物p,p′-二氯偶氮苯(DCAB)进行理论分析以及谱峰归属,发现这些异常峰来自其偶联产物DCAB的偶氮C-N=N-C基团的基频振动. [英文文摘]Surface-enhanced Raman spectroscopy (SERS) on silver nanoparticles is highly sensitive because of surface plasmon resonance. We have studied the structures and photoinduced chemical reactions of p-chloronitrobenzene (PCNB) molecules adsorbed on silver nanoparticles using a combination of SERS and density functional theory (DFT) calculations. When the PCNB molecules are adsorbed to the surface of silver nanoparticles in alkaline solution, the SERS spectra are very different from the normal Raman spectra of PCNB. Comparison of the DFT simulated Raman spectra of PCNB and p,p-dichloroazobenzene (DCAB) indicates that the new peaks in the SERS spectrum of PCNB adsorbed on silver nanoparticles arise from the azo (C－N＝N－C) group of DCAB.国家自然科学基金(20973143, 91027009, 21021002);国家重点基础研究发展规划项目(973)(2009CB930703);厦门大学(2010121020

Theoretical Study of Reactions Between Polysulfides and Ethylene Carbonate and Raman Spectra in Lithium-sulfur Battery

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.Two mechanisms of the reaction between polysulfides( S2-n,n = 2—4) and ethylene carbonate( EC) and Raman spectra of the reactants and main products were investigated by density functional theory( DFT) method.The results showed that the reaction of polysulfides attacking the ethyl carbon of EC is more favorable than that attacking the carbonyl carbon of EC in terms of the activation energies and Gibbs free energies.Sulfur groups in polysulfides display strong Raman signals,so that simulated Raman spectra of the products of the S2-n+ EC reaction significantly change after the reaction.The coordination effect of Li+cation also influenced the simulated Raman spectra of reaction products.DFT results and Raman spectroscopic analysis provide a new insight on structural stability of polysulfides and EC electrolyte in the lithium sulfur battery.国家自然科学基金(批准号:21373172;21321062); 国家基础科学人才培养基金(批准号:J1310024)资助~

Microfabrication and Redox Properties of the Single Microcrystal of Na3Co(CN)6/NaCl Solid Solution

钴氰化钠与铁氰化钠结构类似，而其在固/液界面上的电子转移特性却并不显著. 使用扫描电化学显微镜（SECM）构建了fL~pL体积的电化学微体系. 在微体系中溶剂蒸发，电解质则会浓缩结晶. 当电活性物质与支持电解质的晶格参数匹配时，二者可发生共结晶形成固体溶液. 本文采用该方法制得钴氰化钠/氯化钠固体溶液微晶体，结合微加工技术构建了固体电极/固体溶液界面，该钴氰化钠在固体溶液中即有很好的电子转移特性.Although the molecular structures are similar to each other, the redox property of Co(CN)63- at solid/liquid interface is not so good as Fe(CN)63-. In this paper, scanning electrochemical microscopy (SECM) was adopted to construct an electrochemical microsystem with a volume of fL~pL, in which a micropipette with micrometer-sized orifice was employed as the scanning tip. Due to the evaporation of water, the NaCl electrolyte is concentrated to form a microcrystal. During the crystallization, the redox species Co(CN)63- replaced the sites of NaCl65- unit due to their matching lattice parameters, i.e., the solid solution. Single Na3Co(CN)6/NaCl microcrystal was assembled in-situ between a pair of gold microelectrodes on a microchip to construct the solid/solid interface, which was found to have good voltammetric behavior.国家自然科学基金项目（Nos. 21327002，91323303，21321062，20973142，21061120456）资助作者联系地址：厦门大学 固体表面物理化学国家重点实验室，化学化工学院化学系，福建 厦门 361005Author's Address: State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China通讯作者E-mail：[email protected]