脂肪胺分子离子及质子化脂肪胺分子的碎裂反应

应用碰撞诱导解离(CID)技术研究了电子轰击方法产生的脂肪胺分子离子和化学电离方法产生的质子化脂肪胺分子的碎裂反应。质子化脂肪胺碰撞活化后的主要碎裂通道包括丢失C_XH_(2X)、C_XH_(2X 1)、C_XH_(2X 2)单元及NH_3和生成[C_yH_(2y 1)]及CH_3CH=NH_2~ 离子。脂肪胺分子离子碰撞活化后的主要碎裂通道是丢失C_XH_(2X)、C_XH_(2X 1)及NH_3和生成[C_mH_(2m-1)]~ 、CH_2NH_2~ 及CH_3CHNH_2~ 离子。随着碰撞能的增加,远电荷碎裂反应和电荷诱导碎裂反应之间竞争引起产物离子的的分布发生变化,如[C_mH_(2m-1)]~ 和[C_yH_(2y 1)]~ 离子。自由基机理可以解释质子化脂肪胺分子的远电荷反应。分子内氢抽取可以解释脂肪胺分子离子的碎裂反应。     

芳香环上氢质子的化学位移最大差值与其芳香性的关系

利用化合物的氢质子的核磁共振谱图来研究化合物的分子结构,现在已经成为实验室中常规分析方法之一.有机化合物分子中氢质子的化学位移值除了和实验条件有关外,主要决定于化合物的分子结构.也就是说,是由试样分子中氢质子的结构环境决定的.因此,人们把核磁共振谱中的化学位移值和分子的红外光谱峰值都看成是一个化合物分子的“指纹”数     

用锇胺分子氢配合物作为探针研究药物与核苷酸的配位 动力学

研究了脱氧鸟苷酸(dGMP)及仅有一个配位位点的类似物—咪唑和磷酸氢二钠、磷酸二氢钠与探针的作用,结果表明：dGMP与探针的结合并非咪唑氮和磷酸氧与探针配位结果的简单加和。采用核磁和紫外-停留手段研究了药剂Me~2SnCl~2,Bu~2SnCl~2在不同浓度下与探针竞争dGMP配位位点的溶液化学及其反应动力学,得到了探针和药物与dGMP的结合位点、结合常数以及其动力学结果,对一些反应的机理作出了诠释。     

二维TiC层表面H2的化学吸附与物理吸附

第一性原理计算研究发现由于二维TiC单原子层具有高的比表面积与大量的暴露在表面的Ti原子,其是一种非常有潜力的储氢材料.计算结果显示H2可以在二维TiC单原子层表面进行物理吸附与化学吸附.其中化学吸附能为每个氢分子0.36 eV,物理吸附能是每个氢分子0.09 eV.覆盖度为1和1/4层(ML)时,H2分子在二维TiC单原子层表面的离解势垒分别为1.12和0.33 eV.因此,除了物理吸附与化学吸附,TiC表面还存在H单原子吸附.最大的H2储存率可以达到7.69％(质量分数).其中,离解的H原子、化学吸附的H2、物理吸附的H2的储存率分别为1.54％、3.07％、3.07％.符合Kubas吸附特征的储存率为3.07％.化学吸附能随覆盖度的变化非常小,这有利于H2分子的吸附与释放.     

二维TiC 层表面H2的化学吸附与物理吸附

第一性原理计算研究发现由于二维TiC单原子层具有高的比表面积与大量的暴露在表面的Ti原子,其是一种非常有潜力的储氢材料.计算结果显示H2可以在二维TiC单原子层表面进行物理吸附与化学吸附.其中化学吸附能为每个氢分子0.36 eV,物理吸附能是每个氢分子0.09 eV.覆盖度为1和1/4层(ML)时,H2分子在二维TiC单原子层表面的离解势垒分别为1.12和0.33 eV.因此,除了物理吸附与化学吸附,TiC表面还存在H单原子吸附.最大的H2储存率可以达到7.69%(质量分数).其中,离解的H原子、化学吸附的H2、物理吸附的H2的储存率分别为1.54%、3.07%、3.07%.符合Kubas吸附特征的储存率为3.07%.化学吸附能随覆盖度的变化非常小,这有利于H2分子的吸附与释放.     

以锇的分子氢配合物作~1HNMR探针研究抗癌金属化合物与脱氧鸟苷酸的配位作用

锇的分子氢配合物[trans-en_2Os(η-H_2)]~(2+)(en,乙二胺)是一种新的生物分子~1H NMR识别探针.本文首次以该探针研究了抗癌金属化合物二氯二茂钛、二氯二乙基锡、二乙基邻菲咯啉二氯合锡及顺铂与脱氧鸟苷酸(dGMP)在接近生理条件下重水溶液中的配位作用.结果表明,前三者主要与dGMP的磷酸氧发生强的配位作用,而顺铂主要与dGMP的碱基N(7)发生配位作用.     

粉状白钨酸的研究——Ⅵ.多种偏钨酸盐的PMR谱研究

本文采用PMR技术,研究了由粉状白钨酸制得的偏钨酸钾、钠、铵以及有机铵([C_2H_5-NH_3]~ 、[(C_2H_5)_2NH_2]~ 的阴离子结构;通过测定分子中不可交换氢的数目和氢峰的化学位移,肯定了它们都具有Keggin结构,并讨论了影响化学位移的因素。     

浅析药物化学中含有标记氢的药物命名

正确地对药物分子进行化学命名是药物化学教学中非常重要的部分。对于含有标记氢的药物分子的命名一直是药物化学教学中的难点。将药物化学教材中含有标记氢的化合物进行了归类,并分别举例来分析它们的命名。     

特殊氢方法预测丙氨酸-α-四肽构象稳定性

使用B3LYP/6-31G*方法优化得到了丙氨酸-α-四肽分子的48个稳定构象.定义了丙氨酸-α-多肽中的特殊氢原子,对构象中与特殊氢原子有关的主要非键相互作用进行分析,提出了使用与特殊氢原子有关的非键相互作用来预测多肽构象的相对稳定性,并将之称为特殊氢方法.基于丙氨酸-α-二肽分子的5个构象和三肽分子的7个构象,确定了特殊氢方法中的与特殊氢原子有关的非键相互作用参数.利用特殊氢方法预测丙氨酸-α-四肽分子的48个构象的相对稳定性,与B3LYP/6-31G*方法的相对能量比较,得到了满意的结果.特殊氢方法得到的相对能量(Y)和B3LYP/6-31G*方法得到的相对能量(X)的线性相关方程为Y=0.9296X 2.2041,相关系数R=0.9532,标准偏差为3.0kJ/mol,偏差绝对值≤4.18kJ/mol的构象占87.5%.     

综合化学实验中空气敏感合成实验的选取和教学

选择"硅基芳胺的合成与表征"作为综合化学实验"无水无氧合成技术"的教学内容,实验涉及特殊用途玻璃仪器的干燥与组装、空气敏感物质的操作、惰性气体保护下的化学反应、溶剂浓缩、萃取、少量液体的减压蒸馏以及结构测定等操作。深入分析了无水无氧反应装置的准备、溶剂和物料的转移、正丁基锂的取用、双排管和施伦克玻璃仪器的使用等操作细节问题,并对产物的核磁共振氢谱进行了解析。通过该实验,学生能够实践较高层次的化学实验操作,对拓宽学生专业知识面、提高学生综合实验操作技能有良好的教学效果。     

The axial long-range interaction in 1,4,7,10-tetraazacyclotridecanenickel(ii) bis-tetraethynilborate Ni([13]aneN4)(teb)2

In Ni([13]aneN₄)(teb)₂ (1) axial long-range interaction with the teb anions leads to bipyramidal coordination of Ni (coordination number 4+2), whereas in 1,4,8,11-tetraazaundecanenickel bis-tetraethynilborate, [Ni(2,3,2-tet)teb]teb (2) only one of the teb anions is involved in coordination. Shortening of the equatorial Ni-N bond by 0.1 Å in1 compared with2 leads to elongation of the axial secondary bonds by about 0.6 Å.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1492–1493, August, 1993.The authors are grateful to Dr. Yu. N. Shevchenko and Dr. A. N. Yesaulenko (L. V. Pisarzhevsky Institute of Physical Chemistry of the Academy of Sciences of Ukraine) for submitting the samples for X-ray investigation, for their interest in the work, and for helpful discussion.     

Theoretical study of the conformational states of triosmium clusters with a chiral µ-1-NH pinane ligand

This paper reports a theoretical investigation of the conformations of triosmium clusters with a chiral pinane ligand (μ-H)Os₃(CO)₁₀(μ-NHC₁₀H₁₇). The potential curves of internal rotation of the organic ligand relative to the N-C bond are plotted for the cluster complexes. The structures of possible conformers are considered, and reasons for their stability are revealed. The barrier of rotation around the N-C bond of the terpenoid is 186.6 kJ/mol for crystals and ∼140 kJ/mol for solutions. Due to this, the free rotation of the ligand is hindered in both cases. The effects of the intra-and intermolecular interactions on the conformational state of the cluster complex are analyzed. Original Russian Text Copyright ? 2007 by V. A. Potemkin, V. A. Maksakov, and V. S. Korenev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 230–235, March–April, 2007.     

Theoretical study of the conformational states of triosmium clusters with a chiral pinane ligand

A theoretical study of the conformational state of triosmium clusters with a chiral pinane ligand (μ-H)Os₃(CO)₁₀(μ-ONC₁₀H₁₄) has been performed. The potential curves of internal rotation of organic ligands around the N-C bond in cluster complexes in the crystalline state and in various solvents with continual consideration for the parameters of the latter have been determined. The structures of conceivable conformers and isomers are considered; the factors responsible for their formation and stability are examined. The relations between the conformational and crystalline structures of the cluster and the effect of intra-and intermolecular interactions on its structure are revealed.     

Highly Sensitive and Selective Molecular Probes for Chromo-Fluorogenic Sensing of Carbon Monoxide in Air,Aqueous Solution and Cells

Optical sensing offers a low-cost and effective means to sense carbon monoxide in air and in solution. This contribution reports the synthesis of a new series of vinyl complexes [Ru(CH=CHR)Cl(CO)(TBTD)(PPh₃)₂] (R=aryl, TBTD=5-(3-thienyl)-2,1,3-benzothiadiazole) and shows them to be highly sensitive and selective probes for carbon monoxide in both solution and air. Depending on the vinyl substituent, chromogenic and fluorogenic responses signalled the presence of this invisible, odourless, tasteless and toxic gas. Adsorbing the complexes on silica produced colorimetric probes for the ′naked eye′ detection of CO in the gas phase with a limit of detection as low as 8 ppm in some cases, while the release of the TBTD fluorophore allowed detection at much lower concentrations through the fluorescence response. Structural data were obtained by single-crystal X-ray diffraction techniques, while the photophysical behaviour was explored computationally using TD-DFT experiments. The systems were also shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. By introducing a poly(ethylene)glycol chain to the vinyl functionality, water compatibility was achieved and these non-cytotoxic complexes were employed in the sensing of CO in HeLa cells, offering a simple and rapid system for sensing this gasotransmitter in this challenging medium.     

Labilizing the Photoinert: Extraordinarily Facile Photochemical Ligand Ejection in an [Os(N^N)3]2+ Complex

Whilst [Os(N^N)₃]²⁺ complexes are supposed to be photochemically inert to ligand loss, the complex [Os(btz)₃]²⁺ (btz=1,1′‐dibenzyl‐4,4′‐bi‐1,2,3‐triazolyl) undergoes unprecedented photolytic reactivity to liberate free btz (Φ₃₆₃≈1.2 %). Further, both cis and trans isomers of the photodechelated ligand‐loss solvento intermediate [Os(κ²‐btz)₂(κ¹‐btz)(NCMe)]²⁺ are unambiguously observed and characterized by NMR spectroscopy and mass spectrometry.     

The Simultaneous Spectrophotometric Determination of Osmium and Ruthenium

Abstract

A spectrophotometric procedure is described for the simultaneous determination of osmium and ruthenium in the form of bromo complexes. It was found that a blue ruthenium-thiourea complex could be formed in 6.7 M HBr solutions while the osmium could be maintained as the hexabromoosmate complex. Absorption maxima were at 620 μ for the ruthenium complex and at 446 μ for the osmium complex. Molar absorptivities for the ruthenium complex were 2.47 × 10³ at 620 μ and 763 at 446 μ. For the osmium complex molar absorptivities were 328 at 620 μ and 6.81 × 10³ at 446 μ. The method is useable over the range of 5 to 30 ppm with an absolute error of = 1 ppm over the range. Other platinum metals interfere.     

Light Harvesting and Directional Energy Transfer in Long‐Lived Homo‐ and Heterotrimetallic Complexes of FeII,RuII, and OsII

A new family of trimetallic complexes of the form [(bpy)₂M(phen‐Hbzim‐tpy)M′(tpy‐Hbzim‐phen)M(bpy)₂]⁶⁺ (M=Ru^II, Os; M′=Fe^II, Ru^II, Os; bpy=2,2′‐bipyridine) derived from heteroditopic phenanthroline–terpyridine bridge 2‐{4‐[2,6‐di(pyridin‐2‐yl) pyridine‐4‐yl]phenyl}‐1H‐imidazole[4,5‐f][1,10]phenanthroline (phen‐Hbzim‐tpy) were prepared and fully characterized. Zn²⁺ was used to prepare mixed‐metal trimetallic complexes in situ by coordinating with the free tpy site of the monometallic precursors. The complexes show intense absorptions throughout the UV/Vis region and also exhibit luminescence at room temperature. The redox behavior of the compounds is characterized by several metal‐centered reversible oxidation and ligand‐centered reduction processes. Steady‐state and time‐resolved luminescence data show that the potentially luminescent Ru^II‐ and Os^II‐based triplet metal‐to‐ligand charge‐transfer (³MLCT) excited states in the triads are quantitatively quenched, most likely by intercomponent energy transfer to the lower lying ³MLCT (for Ru and Os) or triplet metal‐centered (³MC) excited states of the Fe^II subunit (nonluminescent). Interestingly, iron did not adversely affect the photophysics of the respective systems. This suggests that the multicomponent molecular‐wire‐like complexes investigated here can behave as efficient light‐harvesting antennas, because all the light absorbed by the various subunits is efficiently channeled to the subunit(s) in which the lowest‐energy excited states are located.     

Conformational States of Triosmium Clusters with Aminoacid Ligands: A Theoretical Study

The conformational state of triosmium clusters with aminoacid ligands (-H)Os₃( -NHCH(R)CO₂Et)(CO)₁₀ (R = H, CH₃) has been studied theoretically. The conformational analysis was performed using the MERA model. The potential curves of the internal rotation of organic ligands in the cluster complexes relative to the HN–CH bond were determined both for individual substances and their solutions. The structures of possible conformers are considered, reasons for their stability are revealed, and variations in the potential curves of internal rotation in various solvents are discussed. The barrier to rotation relative to the HN–CH bond of the alanine derivative is 76.8-78.7 kJ/mole in different media, which hinders free rotation. For the glycine derivative, the same barrier is 37.5-37.9 kJ/mole, which allows for substantial rotational vibrations.