Theoretical Study of the N-NO2 Bond Dissociation Energies for Energetic Materials with Density Functional Theory

The N-NO2 bond dissociation energies （BDEs） for 7 energetic materials were computed by means of accurate density functional theory （B3LYP, B3PW91 and B3P86） with 6-31G＊＊ and 6-311G＊＊ basis sets. By comparing the computed energies and experimental results, we find that the B3P86/6-311G＊＊ method can give good results of BDE, which has the mean absolute deviation of 1.30kcal/mol. In addition, substituent effects were also taken into account. It is noted that the Hammett constants of substituent groups are related to the BDEs of the N-NO2 bond and the bond dissociation energies of the energetic materials studied decrease when increasing the number of NO2 group.     

Catena-dichloro(4,4′-dimethyl-2,2′-bipyridine)Cadmium(Ⅱ),a New One-dimensional Chain with Blue Fluorescent Emission

A new μ-chloro-bridged one-dimensional coordination polymer Cd(dmbpy)Cl2n(dmbpy=4,4′-dimethyl-2,2′-bipyridine) has been synthesized and structurally characterized by elemental analyses=IR=UV spectra and single-crystal X-ray diffraction.The complex crystallizes in the monoclinic system=space group C2/c with a=17.745(4)=b=10.326(2)=c=7.3382(15)=β=106.85(3)o=V=1286.9(4)3=Z=4=C12H12N2Cl2Cd=Mr=367.54=Dc=1.897 g/cm3=F(000)=720=λ(MoKα)=0.71073=μ=2.089 mm-1=R=0.0368 and wR=0.1048 for 1041 observed reflections(I > 2σ(I)).Cadmium(II) adopts a distorted octahedral coordination geometry and adjacent coordination chains are intercalated in a zipper-like fashion into 2D layers through the π-π stacking interactions between dmbpy.Fluorescent     

Doping of C60 fullerene peapods with lithium vapor: Raman spectroscopic and spectroelectrochemical studies

Raman spectroscopy and in situ Raman spectroelectrochemistry have been applied to the study of the lithium vapor doping of C60@SWCNTs (peapods; SWCNT=single-walled carbon nanotube). A strong degree of doping was proven by the disappearance of the radial breathing mode (RBM) of the SWCNTs and by the attenuation of the tangential (TG) band intensity by two orders of magnitude. The lithium doping causes a downshift of the Ag(2) mode of the intratubular C60 by 27 cm(-1) and changes the resonance condition of the encapsulated fullerene. In contrast to potassium vapor doping, the strong downshift of the TG band was not observed for lithium doping. The peapods treated with lithium vapor remained partially doped even when they were exposed to humid air. This was reflected by a reduction in the intensity of the nanotube and the fullerene modes and by the change in the shape of the RBM band compared with that of the undoped sample. The Ag(2) mode of the intratubular fullerene was not resolved after contact of the lithium-doped sample with water. Lithium insertion into the interior of a peapod and its strong interaction with the intratubular fullerene is suggested to be responsible for the air-insensitive residual doping. This residual doping was confirmed by in situ spectroelectrochemical measurements. The TG band of the lithium-doped peapods did not undergo an upshift during the anodic doping, which points to the formation of a stable exohedral metallofullerene peapod.     

Double-helical --> ladder structural transition in the B-DNA is induced by a loss of dispersion energy

The role of the dispersion energy and electrostatic energy on the geometry and stability of the B-DNA helix was investigated. Both molecular dynamics simulations with empirical force field and hybrid quantum mechanical/molecular mechanics molecular dynamics simulations, where the dispersion or electrostatics term is suppressed/increased, on the one hand and an ab initio minimization procedure on the other have shown that the lack of the dispersion term leads to an increase of the vertical separation of the bases as well as to a loss of helicity, thus resulting in a ladder-like structure. A decrease of the electrostatic term produces a separation of the DNA strands. The biological consequences of both electrostatic and dispersion forces in DNA are enormous, and without either of them, DNA would become unstable and unable to provide the storage and transfer of genetic information.     

Rh-Mn-Li/SiO2催化剂的吸附量热和红外研究

通过在最优Rh含量基础上对金属配比的再优化,成功地改进了Rh-Mn-Li/SiO2催化剂的CO加氢性能;并采用微量吸附量热和红外等表征手段,考察了助剂Mn和Li促进作用的本质.结果表明:助剂Mn和Li的添加,使孪式和线式吸附CO的碳氧键强度增加,并同时削弱了桥式吸附CO的碳氧键或者使其转化为更易于解离的倾斜式CO吸附物种,从而同时增加了Rh基催化剂的CO解离和插入能力,提高了其活性和C2含氧化合物选择性.另一方面,Mn和Li的添加显著地降低了Rh基催化剂表面H的数量和稳定性.催化剂加氢能力显著降低极大地抑制了CH4的生成,从而有利于C2含氧化合物选择性的进一步提高.     

高效液相色谱法测定黄姜中皂素

黄姜中皂素经过酸解释放,用ASE200萃取机萃取于甲醇中,然后用高效液相色谱法测定.色谱分离采用YWG-C18柱,以甲醇-水(95 5)溶液为流动相,于210 nm波长处检测.方法的检出限0.2 mg·L-1,线性范围为0.01～2.93 g·L-1.方法的回收率在97.1%～99.8%范围内,4个实际样品测定结果的相对标准偏差(n=7)为1.1%～1.5%.     

药物心脏毒性基团模型的构建

本文根据文献报道的已知药物对hERG的阻滞活性数据,运用Catalyst软件构建了可以初步预测药物心脏毒性作用的模型,并根据该模型得到的结构特征分析了药物具有hERG阻滞活性的结构特点,以便研究者在药物设计过程中进行合理规避,减小药物开发初期的投入。本研究构建的药物心脏毒性基团模型具有四个特征：两个芳环叠合中心,一个静电中心以及一个疏水中心。各项评价参数和验证数据均显示该模型具有良好的心脏毒性预测能力（图1）。     

二十四种作为麝香酮及类似大环酮重要中间体的长链二酮的仿生合成

烷基取代的大环酮（例如,名贵香料麝香酮）是珍贵的香料,天然来源稀少,它的人工合成一直是有机合成中的一个研究热点和难点。在本文中,受四氢叶酸辅酶的一碳单元转移反应的启发,作者以双苯并咪唑盐作为四氢叶酸辅酶模型,利用格利雅试剂与双苯并咪唑盐的加成-水解反应,成功合成了二十四种作为麝香酮及类似大环酮重要前体的长链二酮,同时,提供了一种麝香酮及类似大环酮的仿生合成新方法。     

(2S,5S)-吡咯烷-2,5-二羧酸催化羟基丙酮的不对称Mannich反应

将(2S,5S)-吡咯烷-2,5-二羧酸用于催化羟基丙酮与苯胺和苯甲醛的直接不对称Mannich反应,以较好的收率(64~95%)和最高96% ee得到了syn-1,2-氨基醇化合物。     

聚二烯丙基二甲基氯化铵在质子交换膜表面静电自组装过程的热力学研究

本文通过热化学方法设计了PDDA滴定质子交换膜,并研究了高分子的静电自组装过程。通过非线性拟合数据分析,求出了自组装过程的焓变（ ）和结合常数（K）。根据该反应过程中的热力学参数,可知自组装过程是“焓驱动”反应。热量的放出代表着能量的降低,有利于反应的发生;而自由度的减小不利于反应的发生。对于每个离子键的形成,单分子DDA的焓变超过了PDDA,这是因为小分子能够更加自由地结合到膜上,而高分子PDDA有一定的位阻效应。