基于汞离子高选择识别有机硒化合物的合成和性质研究

合成了9,10-二(2-苄硒基)乙氧基蒽,并通过1H NMR、13C NMR、IR和MS对其进行了结构表征,采用荧光光谱及1H NMR滴定法研究了其对汞离子的识别。结果表明,所合成的化合物对汞离子具有较强的选择性识别性能,在识别过程中亚甲基的峰位发生了较大变化,同时荧光明显增强,呈现出典型"关-开"荧光化学传感器的特性。     

Intracellular Modulation of Excited‐State Dynamics in a Chromophore Dyad: Differential Enhancement of Photocytotoxicity Targeting Cancer Cells

The photosensitized generation of reactive oxygen species, and particularly of singlet oxygen [O₂(a¹Δ_g)], is the essence of photodynamic action exploited in photodynamic therapy. The ability to switch singlet oxygen generation on/off would be highly valuable, especially when it is linked to a cancer‐related cellular parameter. Building on recent findings related to intersystem crossing efficiency, we designed a dimeric BODIPY dye with reduced symmetry, which is ineffective as a photosensitizer unless it is activated by a reaction with intracellular glutathione (GSH). The reaction alters the properties of both the ground and excited states, consequently enabling the efficient generation of singlet oxygen. Remarkably, the designed photosensitizer can discriminate between different concentrations of GSH in normal and cancer cells and thus remains inefficient as a photosensitizer inside a normal cell while being transformed into a lethal singlet oxygen source in cancer cells. This is the first demonstration of such a difference in the intracellular activity of a photosensitizer.     

新型双硒化合物合成及其对汞离子的识别研究

合成了9,10-二(2-苄硒基)乙氧基蒽,并通过1H NMR、13C NMR、IR和MS对其进行了结构表征,采用荧光光谱及1H NMR滴定法研究了其对汞离子的识别。结果表明,所合成的化合物对汞离子具有较强的选择性识别性能,在识别过程中亚甲基的峰位发生了较大变化,同时荧光明显增强,呈现出典型"关-开"荧光化学传感器的特性。     

高速列车的关键力学问题

在过去10 年时间, 中国和谐号系列高速列车经历了一系列速度上的飞跃. 在最初引进消化吸收基础上, 研制了新一代高速列车并大规模投入运营, 伴随这一过程的大量试验与工程实践, 大大促进了对高速铁路这样一个车- 线- 网- 气流强耦合的复杂大系统中的关键力学问题的深入理解和全面研究. 该文将从6 个方面对高速列车研制和运行过程中的典型力学问题的研究进展以及未来的研究方向做一个梳理. 考虑到这样一个大系统的复杂性,同时也为了使对高速列车感兴趣的技术与科研人员对这些力学问题有一个比较全面的认识, 文中将分别就高速列车的空气动力学、弓网关系、车体振动与车体模态设计、车体运行稳定性、高速轮轨关系、关键结构的运行可靠性和列车噪声等方面的研究进行总结和展望. 同时也对中国及国际高速列车发展趋势及其中的力学问题做了一个简要介绍.      

光促进下N,N-二甲基甲酰胺作为一氧化碳源的烯烃氢酯化反应

 研究了光照下以N,N-二甲基甲酰胺(DMF)为一氧化碳源的烯烃氢酯化反应. 结果表明,在常温常压和光照射条件下DMF可以分解得到CO,新生成的CO在光促进下可以直接与CH3OH-DMF溶液中的底物1-辛烯在温和条件和非贵金属钴化合物(Co(OAc)2,CoCl2,Co(en)3Cl2和大环钴[Co(14)4,11-二烯-N4]I2)催化下进行氢酯化反应,反应中DMF既是溶剂,又是原料. H13CON(CH3)2同位素示踪实验证实了这一结果. 在反应体系中通入二氧化碳可以大大提高反应的转化率、产率及选择性. 13CO2同位素示踪实验表明,CO2并未参与产物的形成,其作用是中和DMF分解产生的HN(CH3)2,从而有利于DMF的光促分解.     

Effects of thermal activation conditions on the microstructure regulation of corncob-derived activated carbon for hydrogen storage

Activated carbons derived from corncob （CACs） were prepared by pyrolysis carbonization and KOH activation. Through modifying activation conditions, samples with large pore volume and ultrahigh BET specific surface area could be obtained. The sample achieved the highest hydrogen uptake capacity of 5.80 wt% at 40 bar and -196℃ The as-obtained samples were characterized by N2-sorption, transmission electron microscopy （TEM） and scanning electron microscopy （SEM）. Besides, thermogravimetric analysis was also employed to investigate the activation behavior of CACs. Detailed investigation on the activation parameters reveals that moderate activation temperature and heating rate are favorable for preparing CACs with high surface area, large pore volume and optimal pore size distribution. Meanwhile, the micropore volume between 0.65 nm and 0.85 nm along with BET surface area and total pore volume has great effects on hydrogen uptake capacities. The present results indicate that CACs are the most promising materials for hydrogen storage application.     

光促进温和条件下溴代烷烃与甲酸甲酯的羰基化反应

研究了光促进温和条件下,以甲酸甲酯为C1源,非贵金属钴盐、铜盐催化的溴代烷烃的羰基化反应.实验表明,在光促进下,钴盐、铜盐均可催化溴代烷烃与甲酸甲酯的羰基化反应,得到相应的羧酸甲酯.钴盐催化下,碱性添加物NaOAc对反应有很好的促进作用,直链溴代烷烃在反应中除了得到相应的正构酯外,还有少量异构酯生成;铜盐催化下,直链溴代烷烃在反应中主要生成相应的正构酯.机理研究表明,在光照下甲酸甲酯先分解为CO和CH3OH,再与溴代烷烃进行羰基化反应.     

Synthesis, structures, and properties of two three-dimensional metal-organic frameworks, based on concurrent ligand extension

A tritopic carboxylate ligand, tris(4'-carboxybiphenyl)amine (L-H(3)), has been synthesized and applied in the construction of microporous metal-organic frameworks (MOFs). Two novel metal-organic frameworks (MOFs), {[Zn(2)(L)(OH)]·2DMF·H(2)O}(∞) (1) and {[Cu(L-H)(DMA)]·DMA·2H(2)O}(∞) (2), have been constructed out of L-H(3), Zn(2+), and Cu(2+), respectively. 1 has a 2-fold interpenetrating three-dimensional framework formed by L connectors and the [Zn(2)(CO(2))(3)] secondary building units (SBUs). As for 1, it is worth pointing out that one μ(2)-OH group links two Zn atoms between two neighboring SBUs to produce interesting Zn-O-Zn zigzag chains in the structure. 2 has a two-dimensional grid sheet formed by L-H connectors and the typical paddle-wheel [Cu(2)(CO(2))(4)] SBUs. Two-dimensional (2D) sheets nest with each other, which finally forms a three-dimensional (3D) nested framework. Two MOFs are characterized by infrared (IR) spectroscopy, thermogravimetry, single-crystal and elemental analyses, and powder X-ray diffraction methods. Framework 1' exhibits high permanent porosity (Langmuir surface area = 848 m(2)/g), high thermal stability (up to 450 °C), highly active properties for Friedel-Crafts alkylation reaction, as well as the potential application for the CO(2) gas storage and luminescent material. The catalytic results reveal that 2' is indeed an efficient heterogeneous catalyst for olefin epoxidation reactions.     

铜锌超氧化物歧化酶与丝氨酸钴(Ⅱ)的相互作用

The effect of changing the amount of externally added cobalt(Ⅱ) serine, an organic metal compound, and the pH value of the enzyme solution on the interaction of copper zinc superoxide dismutase (Cu 2Zn 2SOD) with cobalt(Ⅱ) serine was studied by means of visible spectroscopy, inductively coupled plasma atomic emission spectrometry and measurement of enzyme activity. It was found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in Cu 2Zn 2SOD with cobalt(Ⅱ) serine. As a result, part of the metal ions in the metalloenzyme were replaced by Co ion to form Co(Ⅱ) substituted derivatives of SOD and the catalytic activity of the enzyme decreased.     

添加物对光促进下环己烯与二氧化碳羰基化反应的影响

Owing to the greenhouse effect, the rise of carbon dioxide concentration in the atmosphere is a global environmental issue.