甲硫醇在Cu(111)表面的解离吸附: 密度泛函理论研究

采用基于密度泛函理论的第一性原理方法和平板模型研究了CH₃SH分子在Cu(111)表面的吸附反应.系统地计算了S原子在不同位置以不同方式吸附的一系列构型, 第一次得到未解离的CH₃SH分子在Cu(111)表面顶位上的稳定吸附构型,该构型吸附属于弱的化学吸附, 吸附能为0.39 eV. 计算同时发现在热力学上解离结构比未解离结构更加稳定. 解离的CH₃S吸附在桥位和中空位之间, 吸附能为0.75-0.77 eV. 计算分析了未解离吸附到解离吸附的两条反应路径, 最小能量路径的能垒为0.57 eV. 计算结果还表明S―H键断裂后的H原子并不是以H₂分子的形式从表面解吸附而是以与表面成键的形式存在. 通过比较S原子在独立的CH₃SH分子和吸附状态下的局域态密度, 发现S―H键断裂后S原子和表面的键合强于未断裂时S原子和表面的键合.     

LiBa0.95-yBO3:0.05Tb3+,yBi3+荧光粉的制备及荧光性质

以硼酸和碳酸盐为原料,用高温固相法制备了可被（近）紫外光（369、254 nm）有效激发的Tb³⁺单掺杂LiBa_1-xBO₃：xTb³⁺（物质的量分数x=0.02、0.03、0.04、0.05、0.06、0.07）及Bi³⁺和Tb³⁺共掺杂LiBa_0.95-yBO₃：0.05Tb³⁺,yBi³⁺（物质的量分数y=0.02、0.03、0.04、0.05、0.06、0.07）的2个系列荧光粉,产物的结构和形貌分别用粉末X射线衍射（PXRD）和扫描电子显微镜进行表征。PXRD测定结果表明2个系列的产物均为纯相LiBaBO₃。通过对第一系列产物荧光光谱的测定,筛选出发光强度最好的产物,据此确定铽离子的最佳掺杂量;在此基础上制备出铋离子掺杂量不同的第二系列荧光粉。荧光光谱测定的实验结果表明,Tb³⁺/Bi³⁺共掺杂的荧光粉的发光强度好于Tb³⁺单掺杂的荧光粉,这说明Bi³⁺对Tb³⁺有敏化作用;而且随着Bi³⁺掺杂量的增加,产物的荧光强度表现出先增加后减小的趋势,当Bi³⁺的掺杂量y=0.03时,产物的荧光强度达到最大。Bi³⁺和Tb³⁺之间存在偶极-四极相互作用而进行能量传递。系列荧光粉的CIE坐标显示其发光颜色在一定程度上呈现出由绿色光到白光的渐变趋势。     

两个4-[(8-羟基-5-喹啉)偶氮]苯磺酸配合物的合成、结构及性质研究

以4-[(8-羟基-5-喹啉)偶氮]苯磺酸(H₂L)为配体,采用溶剂热合成法合成了两个配合物[CuL(en)]·0.5H₂O (1)和[CuL₂][Cu(en)₂]·2H₂O (2)(en=乙二胺),并采用单晶X-射线衍射、红外光谱、元素分析、X-射线粉末衍射和热重分析对其进行表征。化合物1和2通过氢键和π…π相互作用连接形成了三维超分子网格。此外,还研究了两个化合物的荧光性质。     

BODIPY类近红外荧光染料的研究进展

近红外BODIPY分子是一类新兴的荧光染料, 因其具有优异的光物理和光化学性能而得到广泛的研究, 已成为一个新兴的研究热点。本文综述了近年来BODIPY类近红外荧光分子的设计、合成及应用的最新研究进展, 并展望了其未来的发展方向和应用前景。     

An updated version of the computational package SIMPRE that uses the standard conventions for Stevens crystal field parameters

The crystal field approach used by SIMPRE is analyzed, verifying the exactness of the results concerning energy levels and magnetic properties calculated by the package. To coincide with the prevailing conventions, we reformulate the presentation of the crystal field parameters, so that the results are now, also from a formal point of view, strictly correct. New calculations are presented to test the influence of neglecting the excited J states, a common but critical approximation employed by SIMPRE. For that, we examine the case of Er(trensal) complex (H₃trensal = 2,2′,2″‐tris(salicylideneimino)triethylamine) where the influence of this approximation is found to be minimal. A patched version of the code, SIMPRE 1.1, and an updated version of the user manual are now available. Finally, we comment on “Software package SIMPRE – revisited,” which apparently revisits a software package without inspecting or using the code. © 2014 Wiley Periodicals, Inc.     

Effect of HAP on Stability and Plugging Property of LPFR Dispersion

To improve the stability and plugging property of low-solubility phenol formaldehyde resin (LPFR) in the injection water from Daqing Oilfield, hydrophobically associating polymers (HAP) as a stabilizing agent were used. The size and zeta potential of LPFR, LPFR/HAP molecule aggregates, and turbidity and plugging properties of LPFR dispersions were measured in deionized water, simulation water, and injection water, respectively. The results show that the hydrophobic grouping on the HAP molecule has a similar molecular structure as LPFR, and HAP and LPFR can form complex molecule aggregates in the injection water. The zeta potential of LPFR/HAP molecule aggregates is larger than that of LPFR molecule aggregates. Therefore, the repulsive force operating between LPFR/HAP complex molecule aggregates is increased. HAP enhances the stability of LPFR in the injection water and plugging property of LPFR dispersion in porous medium.     

Highly Efficient Orange and Warm White Phosphorescent OLEDs Based on a Host Material with a Carbazole–Fluorenyl Hybrid

A new carbazole–fluorenyl hybrid compound, 3,3′(2,7‐di(naphthaline‐2‐yl)‐9H‐fluorene‐9,9‐diyl)bis(9‐phenyl‐9H‐carbazole) (NFBC) was synthesized and characterized. The compound exhibits blue‐violet emission both in solution and in film, with peaks centered at 404 and 420 nm. In addition to the application as a blue emitter, NFBC is demonstrated to be a good host for phosphorescent dopants. By doping Ir(2‐phq)₃ in NFBC, a highly efficient orange organic light‐emitting diode (OLED) with a maximum efficiency of 32 cd A^?1 (26.5 Lm W^?1) was obtained. Unlike most phosphorescent OLEDs, the device prepared in our study shows little efficiency roll‐off at high brightness and maintains current efficiencies of 31.9 and 26.8 cd A^?1 at a luminance of 1000 and 10 000 cd m^?2, respectively. By using NFBC simultaneously as a blue fluorescence emitter and as a host for a phosphorescent dopant, a warm white OLED with a maximum efficiency of 22.9 Lm W^?1 (21.9 cd A^?1) was also obtained.     

o‐Fluorination of Aromatic Azides Yields Improved Azido‐Based Fluorescent Probes for Hydrogen Sulfide: Synthesis,Spectra, and Bioimaging

Hydrogen sulfide (H₂S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H₂S in real time, new coumarin‐ and boron‐dipyrromethene‐based fluorescent turn‐on probes were developed for fast sensing of H₂S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H₂S. On the basis of o‐fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H₂S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H₂S and D ‐cysteine‐dependent endogenously produced H₂S in living cells, which makes them promising tools for potential applications in H₂S biology.     

(5RS)‐5‐(4‐Methoxyphenyl)‐2‐(methylsulfanyl)benzo[g]pyrimido[4,5‐b]quinoline‐4,6,11(3H,5H,12H)‐trione,with Z′ = 3, forms a three‐dimensional hydrogen‐bonded framework containing five types of hydrogen bond

The title compound, C₂₃H₁₇N₃O₄S, crystallizes with Z′ = 3 in the space group P. Two of the three independent molecules are broadly similar in terms of both their molecular conformations and their participation in hydrogen bonds, but the third molecule differs from the other two in both of these respects. The molecules are linked by a combination of N—H...O, N—H...N, C—H...O, C—H...N and C—H...π(arene) hydrogen bonds to form a continuous three‐dimensional framework structure within which a centrosymmetric six‐molecule aggregate can be identified as a key structural element.     

[2,5‐Bis(2,2′‐bipyridyl‐6‐yl)‐3,4‐diazahexa‐2,4‐diene]dichloridomanganese(II): from a mononuclear compound to a three‐dimensional supramolecular framework through C—H...Cl hydrogen bonds and π–π stacking interactions

The title compound, [MnCl₂(C₂₄H₂₀N₆)], has been synthesized and characterized based on the multifunctional ligand 2,5‐bis(2,2′‐bipyridyl‐6‐yl)‐3,4‐diazahexa‐2,4‐diene (L). The Mn^II centre is five‐coordinate with an approximately square‐pyramidal geometry. The L ligand acts as a tridendate chelating ligand. The mononuclear molecules are bridged into a one‐dimensional chain by two C—H...Cl hydrogen bonds. These chains are assembled into a two‐dimensional layer through π–π stacking interactions between adjacent uncoordinated bipyridyl groups. Furthermore, a three‐dimensional supramolecular framework is attained through π–π stacking interactions between adjacent coordinated bipyridyl groups.