Vibrational Spectroscopic Study on Ion Solvation and Ion Association of Lithium Tetrafluoroborate in 4‐Ethoxymethyl‐ethylene Carbonate

应用红外及拉曼光谱研究了不同浓度的四氟硼酸锂在4-乙氧甲基-碳酸乙烯酯溶剂中的离子溶剂化和离子缔合现象。环形变谱带和羰基伸缩振动谱带的分裂,以及骨架环振动谱带的迁移和分裂表明,锂离子与溶剂分子间存在着较强的相互作用,这种相互作用是通过溶剂羰基氧原子实现的。利用光谱拟合技术定量计算了表观溶剂化数。随着电解质锂盐浓度的增加,溶剂化数逐渐由4.32降至1.26。此外,四氟硼酸根v1谱带的分裂表明在高浓度溶液中存在着光谱自由的四氟硼酸根、直接接触离子对和离子对二聚体。     

高氯酸锂甲醇溶液中离子溶剂化和离子缔合现象

通过红外光谱技术探讨了高氯酸锂甲醇溶液中离子与溶剂、离子与离子之间的相互作用。红外光谱分析结果表明:锂离子与溶剂发生了相互作用导致甲醇分子的O-H伸缩振动区蓝移,ClO4-的特征谱带的变化表明了溶液中存在离子缔合。根据密度泛函理论,对不同溶剂化数的配合物结构和两种离子对形式进行优化及热力学性质的计算。     

高浓度LiClO4/丙酮溶液中离子-溶剂和离子-离子的相互作用

利用红外和拉曼光谱技术研究了不同浓度LiClO₄/丙酮溶液中离子-溶剂和离子-离子的相互作用. 红外和拉曼光谱的分析表明, Li^＋与丙酮分子发生了强烈的相互作用, 导致丙酮C—C伸缩振动谱带、C＝O伸缩振动谱带等发生了分裂. Li^＋的溶剂化数随溶液浓度的增加逐渐降低, 在所研究的LiClO₄浓度范围(0.31～3.98 mol•kg^－1)内由3.4减小到1.9. 此外, 根据的谱带变化确定了溶液中存在的多种离子对的形式, 计算了缔合平衡常数, 并与电导实验结果进行了比较, 解释了这两种方法测定的离子缔合常数存在差异的主要原因.     

高浓度LiClO4/丙酮溶液中离子-溶剂和离子-离子的相互作用

利用红外和拉曼光谱技术研究了不同浓度LiClO₄/丙酮溶液中离子-溶剂和离子-离子的相互作用. 红外和拉曼光谱的分析表明, Li^＋与丙酮分子发生了强烈的相互作用, 导致丙酮C—C伸缩振动谱带、C＝O伸缩振动谱带等发生了分裂. Li^＋的溶剂化数随溶液浓度的增加逐渐降低, 在所研究的LiClO₄浓度范围(0.31～3.98 mol•kg^－1)内由3.4减小到1.9. 此外, 根据的谱带变化确定了溶液中存在的多种离子对的形式, 计算了缔合平衡常数, 并与电导实验结果进行了比较, 解释了这两种方法测定的离子缔合常数存在差异的主要原因.     

Li＋在基于N,N-二甲基甲酰胺混合溶剂中的溶剂化

利用红外和拉曼光谱技术研究了Li^＋在不同浓度、不同溶剂组成的LiBF₄/N,N-二甲基甲酰胺-乙腈、LiBF₄/N,N-二甲基甲酰胺-四氢呋喃电解质溶液中的优先溶剂化现象. 红外和拉曼光谱的分析表明, Li^＋主要与DMF分子相互作用, 导致该分子的C＝O伸缩振动谱带、N—C＝O形变谱带、CH₃摇摆谱带等发生了分裂. Li^＋与其它溶剂分子的相互作用较弱, 谱带的分裂现象并不明显. Li^＋溶剂化数的计算显示, Li^＋第一溶剂化层内DMF分子的数目一般大于2, 这说明 Li^＋在混合溶剂体系内优先与DMF分子相互作用. 量子化学计算支持了这一结论.     

NaNO3和NaClO4在N,N-二甲基甲酰胺中的离子溶剂化

利用红外光谱研究了NaNO₃和NaClO₄在N,N-二甲基甲酰胺(DMF)溶剂中发生离子-溶剂和离子-离子的相互作用, 分析结果表明, DMF的OC-N谱带发生了明显的变化. 定量计算了在Na⁺浓度为0.22~1.24 mol/kg范围内的溶剂化数为1~4. 对谱图中酰胺基上C-N和CO的特征峰强度随Na⁺浓度变化的对比, 推测离子溶剂化作用导致DMF的酰胺基内部形成共轭键. 利用量子化学方法进行优化及热力学性质计算, 得到C-N键伸缩振动频率及红外光谱强度变化规律. 优化结构与实验结论相符合. 由NaNO₃的ν₂谱带及NaClO₄的ν₁谱带的解析得到溶液中阴离子缔合效应的一般规律, 并通过阴离子缔合特征峰与酰胺基上的N-C-N面外振动峰(865 cm^-1)的变化情况, 讨论了溶液中的离子溶剂化作用.     

红外光谱法研究氯化钙甲醇溶液的溶剂化性质

利用红外光谱研究了不同浓度氯化钙甲醇溶液中离子-溶剂和离子-离子的相互作用.溶剂分子谱带的变化说明了钙离子与甲醇分子发生了强烈的相互作用,这种作用主要是通过C-O中的氧原子实现,而溶剂甲醇分子的O-H谱带的偏移主要是离子(浓度)促使氢键发生改变.通过对光谱曲线的拟合,可定量计算阳离子溶剂化数,进一步揭示了溶剂化过程的微观性质.     

MnCl2/DMSO溶液的拉曼光谱和理论计算

利用拉曼光谱研究了不同温度和浓度MnCl₂/DMSO溶液体系离子的溶剂化作用, 结果表明, 在0~0.8 mol/L浓度范围内, 随着浓度增加, Mn²⁺与DMSO的相互作用逐渐增强, S=O伸缩振动峰向低波数移动, S=O双键减弱; C—S伸缩振动峰向高波数移动, C—S键增强. 温度升高, S=O双键和C—S键伸缩振动峰均向相反的方向移动, 溶剂化作用减弱. 56 ℃以上, 单体DMSO迅速增加, 与Mn²⁺溶剂化作用的DMSO迅速减少, 二聚体DMSO减少缓慢, 温度对溶剂化作用的影响大于溶剂自身的缔合. 利用密度泛函理论对可能存在的溶剂化构型[Mn(DMSO)_n]²⁺进行了优化、 热力学性质及理论拉曼光谱计算, 从理论上证实了Mn²⁺与DMSO存在相互作用, 导致DMSO的S=O键拉伸和C—S键收缩, 与实验光谱结果一致.     

Li＋在基于N,N-二甲基甲酰胺混合溶剂中的溶剂化

利用红外和拉曼光谱技术研究了Li^＋在不同浓度、不同溶剂组成的LiBF₄/N,N-二甲基甲酰胺-乙腈、LiBF₄/N,N-二甲基甲酰胺-四氢呋喃电解质溶液中的优先溶剂化现象. 红外和拉曼光谱的分析表明, Li^＋主要与DMF分子相互作用, 导致该分子的C＝O伸缩振动谱带、N—C＝O形变谱带、CH₃摇摆谱带等发生了分裂. Li^＋与其它溶剂分子的相互作用较弱, 谱带的分裂现象并不明显. Li^＋溶剂化数的计算显示, Li^＋第一溶剂化层内DMF分子的数目一般大于2, 这说明 Li^＋在混合溶剂体系内优先与DMF分子相互作用. 量子化学计算支持了这一结论.     

LiNO3/N,N-二甲基甲酰胺溶液光谱性质的研究和模拟

利用红外光谱和量子化学计算方法研究了LiNO3/N,N-二甲基甲酰胺(DMF)溶液中离子溶剂化和离子缔合现象,得出了阳离子和阴离子在溶液中的存在形式以及DMF分子间自身的内部结构,并对(DMF)n结构进行了优化及热力学性质计算.在此基础上,提出阳离子进入溶剂化层的机理是,DMF分子之间相互作用形成不同形式的(DMF)n...     

新型水溶性萘啶基荧光材料的制备及性能研究

本文制备得到一种新型萘啶基的水溶性光致发光聚合物:聚丙烯酸(PAA)-2-苄氨基-7-甲基-1,8-萘啶,PAA₅-PAMN₂(PAMN是2-phenmethy-lamino-7-methyl-1,8-naphthyridine的缩写),经光谱分析和密度泛函理论计算,研究了化合物的结构和组成.这种聚合物在酸性和碱性条件下呈现最大的吸收波长分别为364和342 nm.Zn(OAc)₂的加入致使PAA₅-PAMN₂水溶液的荧光猝灭,而当OAc^-改变为NO₃^-时,在荧光强度不断降低的同时,由于NO₃^-离子的配位使最大发射波长从410 nm蓝移到400 nm.Na⁺+离子对其没有明显的荧光猝灭效应.     

<Emphasis Type="Italic">AB initio</Emphasis> quantum chemical study of the reaction mechanism of ethynide ion formation in the C<Subscript>2</Subscript>H<Subscript>2</Subscript>/MOH/DMSO system (M = Li,Na, K)

The reaction mechanism of the formation of alkali metal ethynides C₂H₂ + MOH → C₂HM + H₂O (M = Li, Na, K) is studied for the gas phase (MP2/6-311++G**//RHF/6-31+G*) and also with regard to the solvent effect of dimethyl sulfoxide (DMSO) included within the continuum model. Among all acetylene complexes with alkali metal hydroxides considered (C₂H₂·MOH (M = Li, Na, K)), only the complex with KOH is thermodynamically stable in DMSO solution. The formation of this structure results in activation of the acetylene molecule towards electrophilic attack. The formation of alkali metal ethynide in solution is also thermodynamically favorable only in the system with potassium hydroxide of a whole series of metals considered. Further, the ethynide ion can interact in KCCK·HOH systems.     

<Emphasis Type="Italic">Ab initio</Emphasis> quantum-chemical study of the mechanism of methoxide ion formation in MOH/DMSO/CH<Subscript>3</Subscript>OH systems (M = Li,Na, K)

The profile of the reaction CH₃OH + MOH → CH₃OM + H₂O in the presence of an alkali (MOH, M = Li, Na, K) was investigated by the ab initio quantum-chemical method for the gas phase (with allowance for the solvent) within the continuum model. The proton transfer and the formation of the alkaline methoxide molecule in MOH/DMSO/CH₃OH systems (M = Li, Na, K) in the alkali-methanol pre-reaction complexes can take place without their preliminary dissociation and are barrier-free reactions.     

Novel peripherally substituted zinc phthalocyanine: synthesis,characterization, investigation of photophysicochemical properties and theoretical study

The new thiohexanoic acid substituted zinc phthalocyanine was synthesized and characterized by FT-IR, ¹H–NMR, electronic spectroscopy, and mass spectrometry as well as DFT calculation studies. The photochemical properties (singlet-oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence quantum yields and fluorescence behavior) of the compound were studied in dimethylsulfoxide (DMSO), dimethylformamide (DMF) and tetrahydrofuran (THF). Singlet-oxygen quantum yields ranged from 0.29 to 0.43. However, energy-minimized structure, vibrational frequency, electronic distribution and molecular orbitals were obtained by DFT calculations which were supported by experimental results.     

Synthesis, crystal structure, chemical bonding, and physical properties of the ternary Na/Mg stannide Na2MgSn

A ternary stannide of sodium and magnesium, Na(2)MgSn, was synthesized from the elements, and the crystal structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the Li(2)CuAs structure type (hexagonal, P6(3)/mmc, Z = 2, a = 5.0486(11) ?, c = 10.095(2) ?), and its structure is built up of two-dimensional honeycomb layers of (2)(∞)[(MgSn)(2-)] stacked along the c-axis, with Na atoms as "space fillers". First-principles computations at various levels of density functional theory (DFT) verify that the most stable configuration is the one in which Na and Mg atoms occupy the 4f and 2b sites, respectively, and thus DFT provides a necessary complement to X-ray structural elucidation. Our computations also predict that Na(2)MgSn must be a semiconductor with a small band gap. In accord with these predictions, the electrical resistivity measured for a polycrystalline sample of Na(2)MgSn is 9.6-10.4 mΩ cm in the range of 90-635 K, and the Seebeck coefficient decreases from +390 μV K(-1) (at 300 K) to +150 μV K(-1) (at 430 K).     

Determination of pharmaceutical compounds in aqueous dimethyl sulfoxide by electrospray ionization mass spectrometry

Standard solutions of reserpine, dextromethorphan, imipramine and amitriptyline in dimethyl sulfoxide (DMSO), DMSO containing 0.1% formic acid, and DMSO/H(2)O (1:1, v/v) containing 0.1% formic acid were analyzed by positive electrospray ionization mass spectrometry (ESI-MS). A triple-quadrupole mass spectrometer equipped with a TurboIonspray (TIS) interface was used for the ESI-MS analyses. The samples dissolved in the respective DMSO solution were infused directly into the mass spectrometer at 10 microL/min using an infusion pump. The positive Q1 full-scan (m/z 50-650) mass spectrum of DMSO (MW = 78) showed three main peaks at m/z 79, 101 and 179, corresponding to the protonated molecule [DMSO+H](+), and the sodiated adducts [DMSO+Na](+) and [2DMSO+Na](+), respectively. The ESI of the compounds in DMSO and DMSO containing 0.1% formic acid was promoted by using the TIS gas (GS2) combined with the nebulizer gas (GS1), and TIS source temperature set to 250 degrees C. In contrast, samples dissolved in DMSO/H(2)O (1:1, v/v) containing 0.1% formic were sprayed at a lower temperature (100 degrees C) using only the nebulizer gas. The TIS voltage (V) was optimized in order to establish the lowest voltage necessary to achieve optimum ESI of each pharmaceutical compound with the voltage maintained below the onset potential required to produce a corona discharge at the TIS probe (sprayer). Detection limits of 10 ng/mL were achieved for reserpine, dextromethorphan, imipramine and amitriptyline in each solvent composition.     

N/F掺杂和N-F双掺杂锐钛矿相TiO2(101)表面电子结构的第一性原理计算

采用密度泛函理论(DFT)平面波赝势方法计算了N/F掺杂和N-F双掺杂锐钛矿相TiO2(101)表面的电子结构. 由于DFT方法存在对过渡金属氧化物带隙能的计算结果总是与实际值严重偏离的缺陷, 本文也采用DFT+U(Hubbard 系数)方法对模型的电子结构进行了计算. DFT的计算结果表明N掺杂后, N 2p轨道与O 2p和Ti 3d价带轨道的混合会导致TiO2带隙能的降低, 而F掺杂以及氧空位的引入对材料的电子结构没有明显的影响. DFT+U的计算却给出截然不同的结果, N掺杂并没有导致带隙能的降低, 而只是在带隙中引入一个孤立的杂质能级, 反而F掺杂以及氧空位的引入带来明显的带隙能降低. DFT+U的计算结果与一些实验测量结果能够较好地符合.     

N／F掺杂和N-F双掺杂锐钛矿相TiO2（101）表面电子结构的第一性原理计算

采用密度泛函理论(DFT)平面波赝势方法计算了N/F掺杂和N-F双掺杂锐钛矿相TiO2(101)表面的电子结构.由于DFT方法存在对过渡金属氧化物带隙能的计算结果总是与实际值严重偏离的缺陷,本文也采用DFT+U(Hubbard系数)方法对模型的电子结构进行了计算.DFT的计算结果表明N掺杂后,N2p轨道与O 2p和Ti 3d价带轨道的混合会导致TiO2带隙能的降低,而F掺杂以及氧空位的引入对材料的电子结构没有明显的影响.DFT+U的计算却给出截然不间的结果,N掺杂并没有导致带隙能的降低,而只是在带隙中引入一个孤立的杂质能级,反而F掺杂以及氧空位的引入带来明显的带隙能降低.DFT+U的计算结果与一些实验测量结果能够较好地符合.     

Calculations of dissociation constants of carboxylic acids by empirical and quantum-chemical DFT methods

Dissociation constants of 15 carboxylic acids in water, methanol, and DMSO were calculated by empirical and quantum-chemical DFT methods. The maximal error of the empirical calculation was 1.4%. A comparative analysis of the results obtained was carried out.     

Concentrated Electrolyte for the Sodium–Oxygen Battery: Solvation Structure and Improved Cycle Life

Alkali metal–oxygen batteries are of great interests for energy storage because of their unparalleled theoretical energy densities. Particularly attractive is the emerging Na–O₂ battery because of the formation of superoxide as the discharge product. Dimethyl sulfoxide (DMSO) is a promising solvent for this battery but its instability towards Na makes it impractical in the Na–O₂ battery. Herein we report the enhanced stability of Na in DMSO solutions containing concentrated sodium trifluoromethanesulfonimide (NaTFSI) salts (>3 mol kg^?1). Raman spectra of NaTFSI/DMSO electrolytes and ab initio molecular dynamics simulation reveal the Na⁺ solvation number in DMSO and the formation of Na(DMSO)₃(TFSI)‐like solvation structure. The majority of DMSO molecules solvating Na⁺ in concentrated solutions reduces the available free DMSO molecules that can react with Na and renders the TFSI anion decomposition, which protects Na from reacting with the electrolyte. Using these concentrated electrolytes, Na–O₂ batteries can be cycled forming sodium superoxide (NaO₂) as the sole discharge product with improved long cycle life, highlighting the beneficial role of concentrated electrolytes for Na‐based batteries.