^9^9^mTcO^3^+和^9^9^mTcN^2^+的二胺基二硫醇配合 物在脑中滞留机制的量子 化学研究

N,N'-二(2-巯乙基)-乙二胺(DTEN)作为二胺基二硫醇类配体的模型化合物，CH~3SH作为还原型谷胱甘肽(GSH)的模拟物，用从头算分子轨道理论研究了这两种配合物与CH~3S^-的反应产物。结果表明，CH~3S^-配位到TcO-DTEN的Tc原子上，而将其转化为不能穿越血脑屏障的[TcO-DTEN-SCH~3]^-离子。与此相反，CH~3S^-不能与TcN-DTEN中的Tc配位，后者仍保持可以穿越血脑屏障的中性分子状态。以此解释了^9^9^mTcO^3^+的二胺基二硫醇配合物比相应的^9^9^mTcN^2^+配合物在脑中有较高的滞留。还用从头算分子轨道理论研究了胺基配体与TcO^3^+及TcN^2^+配位时从胺基N上脱去质子的规律。     

THF/H~2O二元团簇中“幻数”现象研究

利用分子束、同步辐射光源和飞行时间质谱研究了HF/H~2O二元团簇体系,观察到了一系列组成为(THF)~n·(H~2O)~mH^+(n=2～5,m=0～n-1)离子峰,其中(THF)~n(H~2O)~n~-~2H^+(n=2～5)离子峰强为“幻数”峰。运用从头算(abinitio)分子轨道法,在HF/3-21G基组水平上对(THF)~n(H~2O)~n~-~2H^+(n=2～4)团簇几何构型进行了优化,计算结果表明团簇离子(THF)~n(H~2O)~n~-~2H^+具有较大的稳定性,解释了实验中观察到的“幻数”现象。     

MgH^+,Mg2H^+量子化学从头计算的研究

用量子化学自洽场分子轨道从头计算方法,采用STO-3G基组计算了MgH~+,Mg_2H~+离子的位能曲线与位能面;给出电子波函数与电子集居数;得到MgH~+的平衡构型键长γ_(Mg-H)1.60A.Mg_2H~+的平衡构型有C_(∞v)与D_(∞h)两类,前者为[Mg—Mg—H]~+,键长γ_(Mg-Mg)2.41,γ_(Mg-H)1.63A;后者为[Mg—H—Mg]~+,γ_(Mg-H)1.73A.前者的总能量比后者低50kcal/mol.还讨论了它们的稳定性.MgH~+的键长计算结果和实测值较吻合,Mg_2H~+的平衡构型计算结果支持了Porter从热力学研究提出的假设.     

二苯二硫和二苄二硫润滑性能的量子化学研究

The molecular geometries optimization and electronic structures of diphenyl disulfide (DPDS) and dibenzyl disulfide (DBDS) compounds were investigated by density functional theory (DFT) and ab initio method at the 6-31G basis set level. The active atoms and bonds of reaction were provided by frontier molecular orbital theory. The molecular orbital parameters of DPDS and DBDS compounds and iron atom cluster were calculated by using density functional theory. The interaction pattern between the organic disulfide compounds and iron atom cluster was discussed based on the approximate rule of orbital energy. Some parameters characterizing the action strength between the organic disulfide compounds and iron atom cluster, including the bonding strength, reactive strength and static action strength, were analyzed by using frontier electron density, super de-localizability, net atomic charge and the interaction energy of chemical adsorption as criteria. The results indicate that S-S chemical bond and C-S chemical bond of the compounds are inclined to be broken when DPDS and DBDS interact with the metal. The anti wear ability order of DPDS and DBDS compounds is DPDS>DBDS, and the extreme pressure ability order of DPDS and DBDS compounds is DBDS>DPDS, and the prediction results based on quantum chemistry calculations are in good accordance with the friction and wear test results.     

CH_3自由基和O（~3P）反应机理的量子化学研究

用分子轨道从头计算MP2（full）方法和密度泛函理论（DFT）中的B3LYP方法 研究了CH_3自由基和三线态O原子反应的微观机理，优化得到了反应途径上的反应 物、过渡态、中间体和产物的几何构型，通过振动分析对过渡态和中间体构型进行 了确认，在G3不平上计算了能量，同时用经典过渡态理论对该反应的绝对速率常数 进行了理论计算。研究结果表明：CH_3自由基与O（~3P）反应有四条不同的放热反 应通道，主反应通道为IM1→TS1→CH_2O + H，同时反应可彻底裂解生成CO, H_2 及H。     

H+ClF→HCl+F微观分支反应机理的从头算分子轨道法研究

用从头算分子轨道法对反应H+ClF→HCl+F的势能面进行了系统的研究。在势能面上找到了与该反应相应的两个过渡态, 并通过对从这两个过渡态出发的内禀反应坐标的分析, 得出了H与ClF生成HCl的反应途径存在着微观分支的结论。同时又由H以不同角度进攻ClF中Cl原子一端反应势垒的变化情况, 对势能面上出现分支的原因作出了解释。     

磷的d轨道在H~3PO分子中的作用

用分子片轨道在分子环境中发生极化的概念研究d轨道在H~3PO分子中的作用。H~3PO分子被分为两个分子片---H~3P和O.在RHF/6-31G^*水平上计算出分子环境中的极化了的分子片轨道(FOM)。再剔除d函数为主的FOM,用剩余的FOM为基进行构型优化,得到与RHF/6-31G^*相近的结果。这一结果说明磷原子的d函数在H~3PO分子中仅仅起一个极化函数的作用,而不是起价轨道作用。     

CH(^4∑^-)+H2O→CH2(^3B1)+OH的直接动态学研究

用从头算方法计算了反应CH(^4∑^-)+H2O→CH2(^3B1)+OH的反应途径。在此基础上, 计算沿反应途径的动态学性质和正则变分过渡态理论的速率常数, 并进行隧道效应校正。结果表明, 电子相关能对反应活化位垒影响较大; 反应存在返回效应和隧道效应, 用正则变分过渡态方法和小曲率近似的隧道校正是有效的。     

二噻啉基二氧化物与镍的络合物[Ni(BiquO2)3]^2^+的立体构型和Ni^2^+的吸收谱

本文通过对[Ni(BiquO2)3]^2^+配位离子中Ni^2^+吸收谱的理论分析, 推导出Ni^2^+的晶场对称性, 以此确定Ni(BiquO2)3X2分子的空间立体结构, 解释这类配合物的电-磁性质和稳定性.     

CH~2(^3B~1)+H~2→CH~3+H的反应途径及动态理论研究

用从头算的UHF/6-31G方法,反应途径哈密顿理论以及变分过渡态理论, 计算了反应CH~2(^3B~1)+H~2→CH~3+H的反应途径.沿反应途径的动态学性质和正则变分过渡态理论的速率常数,用变分过渡态方法处理效果明显;较低温度下考虑隧道效应更重要,而用小曲率近似的校正是有效的;H~2 分子的振动激发对反应速率常数有较大增进.     

稀土冠醚配合物的研究XXI. 单羟基冠醚与钙、稀土元素间的竞争配位及其钙配位化合物的晶体结构

研究了单羟基冠醚配位体6-羟基-2, 3, 9, 10-二苯并-1, 4, 8,11, 14-五氧杂环十六-2, 9-二烯(L)对钙和镧系元素的竞争配位反应, 发现该配位体在我们的实验条件下对钙的配位能力要明显大于对重稀土的配位能力; 同时研究了标题大环配位体和钙的配位化合物的晶体结构, 该配位化合物的分子结构式为[Ca(NO3)(H2O)L](NO3),Mr=528.47, 晶体属单斜晶系, α=1.5285(6), b=0.9713(3),c=1.5134(7)nm, β=98.79(3)ⅲ, V=2.2205nm^3, Dex=1.521g/cm^3,Dc=1.527g/cm^3, Z=4, 空间群为P21/c。     

A theoretical study of the ion pair SN2 reaction between lithium isocyanates with methyl fluoride with inversion and retention mechanism

This paper is devoted to a detailed theoretical study of an ion pair S_N2 reaction LiNCO+CH₃F in the gas phase and in solution at the level of MP2(full)/6-31+G**//HF/6-31+G**. Two possible reaction mechanisms, inversion and retention, are discussed. There are eight possible reaction pathways. The inversion mechanism is more favorable no matter in the gas phase or in solution based on analyses of the transition structures. Methyl isocyanate should form preferentially in the gas phase and more stable methyl cyanate is the main product in solution. The retardation of the reaction in solvents was attributed to the difference in solvation in the separated reactants and in the transition state.     

Tl^3^+─H2O2─Fe^2^+体系的反应动力学研究

本文用Tl(I)离子选择性电极测定了Tl^3^+-H2O2-Fe^2^+体系的反应参数, 据此计算了该体系的反应级数, 得到了反应速率方程式, 对该反应体系的反应机理进行了探讨, 并用稳态处理法对所提出机理进行验证, 其结论与实验所得速率方程完全符合。     

Ab initio quantum chemical studies of the reactions of CF3CFHO2 with HO2

The potential energy surface (PES) for the CF₃CFHO₂+HO₂ reaction has been theoretically investigated using the DFT [B3LYP/6‐311G(d,p)] and B3LYP/6‐311++G(3df,3pd)//B3LYP/6‐311G(d,p) levels of theory. Both singlet and triplet PESs are investigated. The reaction mechanism on the triplet surface is simple. It is revealed that the formation of CF₃CFHOOH+³O₂ is the dominant channel on the triplet surface. On the basis of the ab initio data, the total rate constants for the reaction CF₃CFHO₂+HO₂ in the T = 210–500 K range have been computed using conventional transition state theory with Wigner's tunneling correction and have been fitted by a rate constant expression as k = 1.04 ×10^?12(cm³ molecule^?1 s^?1) exp (700.33/T). Calculated transition state rate constants with Wigner's tunneling correction for the reaction CF₃CFHO₂+HO₂ are in good agreement with the available experimental values. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

DL－苹果酸－丙酮－BrO~3^-－Mn^2^+－H~2SO~4化学振荡 反应诱导期的新特征 及其动力学研究

在前文研究工作的基础上,较详细地研究了DL-苹果酸(以下简称DL-MA)、丙酮(以下简称Act)参与下的新型化学振荡反应及各种影响因素,对各主要参与反应物质在诱导期中的作用、起振原因、诱导期的新特征和可能反应机理进行了较为深入的研究,分别获得DL-MA,KBrO~3,MnSO~4的浓度对诱导期影响的拟合方程。以及诱导期的表观活化参数为E~I~N=68.50kJ·mol^-^1。     

Theoretical study for quercetin/β-cyclodextrin complexes: quantum chemical calculations based on the PM3 and ONIOM2 method

The inclusion interaction between quercetin and β-cyclodextrin (β-CD) binding site has been investigated, based on PM3 and ONIOM2 methods. The obtained results clearly indicate that the orientation in which the B ring of the guest molecule located near the secondary hydroxyls of the β-CD cavity is preferred in the binding energy. Moreover, Analyses regarding the complex structures suggest that one hydrogen bond between 7-hydroxy group (OH) of quercetin and 6-OH of β-CD is formed. This hydrogen bond interaction plays an important role in the bound quercetin/β-CD complex.     

A quantum chemical study of the hydrogen bonding in the CO2⋯HF and N2O⋯HF complexes

Summary Quantum chemical ab initio calculations have been performed for the complex CO₂HF and N₂OHF. The interaction energies were computed through fourth order MBPT and were corrected for basis set superposition errors. Extended polarized basis sets were used which are constructed to give accurate values for electric moments and polarizabilities. The complex NNOHF was found to be bent, while OCOHF is linear, in agreement with experiment. The MBPT calculations give evidence for a second linear isomeric structure FHNNO, a possibility which has also been suggested by recent experimental data. The computed binding energies are: 2.5 kcal/mol for OCOHF, 2.4 kcal/mol for NNOHF, and 3.0 kcal/mol for FHNNO. At the SCF level, the FHNNO complex is less stable than NNOHF, but correlation has a large effect on the geometry and energetics of the latter complex. The NNOHF complex seems to be a system where the positive intramolecular correlation correction prevails over the negative intermolecular component.     

乳酸-丙酮-BrO3^——Mn^2^+-H2SO4化学振荡体系动力学研究

本文报道了与生命代谢过程密切相关的中间物参与的乳酸(以下简称LA)-丙酮(以下简称Act)-BrO3^--Mn^2^+-H2SO4新型化学振荡体系, 考察了振荡体系中诸反应物的初始浓度范围及影响因素, 获得诱导期、振荡周期、振荡寿命所对应的表观活化参数EIN, EP, EL分别为60.68kJ.mol^-^1, 61.03kJ.mol^-^1,135.80kJ.mol^-^1。分析了诱导期的新特征及可能的振荡反应机理。     

(CH3)3C+NO2反应机理的理论研究

用量子化学密度泛函方法,在B3LYP/6-31G*水平下研究了叔丁基自由基(CH3)3C和NO2气体的反应机理.研究表明,该反应是在单、三态势能面上的多通道反应.不同反应通道的产物不同,单态下反应更容易发生.常温下对于一个敞开体系(例如在大气当中),(CH3)3C自由基和NO2作用主要生成比较稳定的化合物(CH3)3CONO和(CH3)3CNO2.这对于消除大气污染起到一定的作用.     

金纳米球/氮掺杂石墨烯量子点固载Ru(bpy)3^2+电致化学发光法检测邻苯二酚

利用还原法制得金纳米球(Au NPs),与氮掺杂石墨烯量子点(NG QDs)杂化后,再以壳聚糖胶黏剂并通过静电作用使Ru(bpy)3^2+负载于其表面形成复合膜,制备了一种新型的固相电致化学发光(ECL)传感器。研究发现,与单一材料相比,Au NPs和NG QDs杂化复合材料作为载体显著提高了发光试剂Ru(bpy)3^2+的ECL信号。根据环境污染物邻苯二酚对该修饰电极ECL信号较强的阻抑作用,建立了测定领苯二酚的新体系。结果表明,Au NPs/NG QDs/Ru(bpy)3^2+修饰电极的ECL信号变化值与邻苯二酚的浓度负对数在5.0 nmol/L^10μmol/L之间呈良好的线性关系,检出限为3.0 nmol/L(r=0.9992)。对5.0μmol/L的邻苯二酚进行10次重复测定,相对标准偏差为4.6%,常见的共存物质不干扰测定,表明该方法的选择性较好。采用该修饰电极成功测定了河水中的邻苯二酚含量。