几种新型双吡唑衍生物缓蚀性能的理论研究

通过量子化学计算中的密度泛函理论(DFT)/B3LYP方法在6-311+G(d,p)水平上对3种新型双毗唑衍生物5,5'-二甲基-4-乙酯基-1'氢-1,3'-二吡唑(Bipl)、1,1',5,5'一四甲基-1氢,1'氢-3,3'-二吡唑(Bip2)和3-(溴甲基)-5,5'-二甲基-1'氢-1,3'-二吡唑(Bip3)的缓释性能与结构关系进行了研究。用Fukui指数分析了分子中反应活性位点。结果表明全局活性参数最高占据轨道能量(E_(HOMO))、偶极矩(μ)、电负性(X)及电子转移数(△N)与缓释性能有良好的关系。缓蚀性能的理论评价结论与实验结果相吻合。     

4,6-双-(5-氨基-3-硝基-1,2,4-三唑-1-基)-5-硝基嘧啶(DANTNP)性能的量子化学研究

用B3LYP法,在6-31G(d,p)基组水平上计算4,6-双-(5-氨基-3-硝基-1,2,4-三唑-1-基)-5-硝基嘧啶(DANTNP)的性能,得其稳定的几何构型和键级;在振动分析的基础上求得体系的振动频率、IR谱及不同温度的热力学性质及温度对热力学性能影响的关系式。用UHF-PM3法探讨其热解机理,求得热解反应时的过渡态和活化能,发现热解始于N-H键断裂时。     

密度泛函方法研究辣椒碱分子的结构和性质

辣椒碱(Capsaicin)在医药、农业和反恐装备方面具有广泛的应用前景.本文用密度泛函理论DFT/B3LYP方法,在6-31+G(d,p)基组水平上对其进行了计算.密度泛函理论方法既考虑了电子相关,又较其他组态相互作用或微扰方法节省机时,其计算结果可靠,被广泛应用于研究各类化合物结构性质.本文获得了辣椒碱分子稳定的几何构象和电荷分布,确定O(12)、N(16)、O(19)、C(37)和C(38)原子,可以作为氢键受体;C(18)与O(19)原子形成一对偶极,它们均是关键药效团的活性部位.通过进行分子轨道特征分析,确定苯环区是参加化学反应时的活性部位.进行的自然键轨道分析结果与分子轨道特征分析结论一致.在振动分析的基础上获得分子的振动频率、IR光谱与实验结论一致;在振动分析的基础上,同时获得不同温度下的热力学性质以及温度对热力学性能影响的关系式,其中,当T＞2 542 K时,热容Cp,mθ会随温度的升高而减小,各表达式和热力学量对深入研究辣椒碱分子的其它热力学性质有帮助.探讨了辣椒碱热分解机理,获得该分子热分解时C-N键的断裂能为306.6 kJ·mol-1.本文为研究辣椒碱类化合物的定量构效关系研究提供理论依据.     

酰基吡唑啉酮配体的设计

利用分子力学方法研究了1－苯基－3－甲基－4－（烟酰）－吡唑啉－5－酮（A）和1－苯基－3－甲基－4－（异烟酰）－吡唑啉－5－酮（B）及反应可能生成的烯醇式异构体（C）、（D）。系统搜索结果可以看出酮式能量最低，和实验结果相吻合，表明设计结果正确，为进一步设计开发新型配体提供了可靠的方法。     

叠氮酸与氨氰环加成反应的理论研究(英文)

采用B3LYP、QCISD、MP2方法在6-311+G(d)基组水平上对叠氮酸与氨氰环加成反应进行了详细研究。首先对所有的反应物、过渡态和产物的构型进行了全参数优化,并用频率分析和内禀反应坐标(IRC)方法对过渡态进行确认。以步长为0.1(amu)1/2 bohr的内禀反应坐标方法在B3LYP/6-311+G(d)方法和基组水平上计算了内禀反应坐标s为(-3.00～3.00)(amu)1/2 bohr范围内反应的键长、振动频率、NBO电荷变化情况。根据统计热力学方法和用Wigner校正的Eyring过渡态理论,计算了(200～450)K温度范围内反应热力学函数及速率常数,探讨了温度对反应的影响。结果表明,反应经过过渡态TS生成5-AT的活化能为117.14 kJ/mol(B3LYP)、130.18 kJ/mol(QCISD)和106.24 kJ/mol(MP2),产物的相对能量为-74.24 kJ/mol(B3LYP)、-87.01 kJ/mol(QCISD)和-79.09 kJ/mol(MP2);反应随温度的升高更具有动力学优势,但在热力学上低温下更易于进行,因此,结合热力学和动力学因素,我们认为(300～350)K是该反应的适宜温度。     

有机缓蚀剂定量构效与活性相关的热力学参数量子化学计算值与缓蚀效率的QSAR研究

用AMI和PM3半经验方法对5种缓蚀剂进行了优化计算并将获得的量化参数与缓蚀性能进行构效关系(QSAR)研究,结果表明,由AMI方法得到的不同温度下的缓蚀剂热力学参数焓和熵的量子化学计算值与该缓蚀剂缓蚀实验的腐蚀电流有良好的相关性。根据所得的相关模型可对缓蚀剂在一定温度范围内的腐蚀电流进行预测,进而预测其缓蚀性能。     

论(Cl_2BN_3)_n(n=1-4)簇合物

用密度泛函论B3LYP/6-311+G*法,计算(C1_2BN_3)_n(n=1-4)簇合物的结构和性质.发现,多聚体(C1_2BN_3)_n(n=2-4)的优化构型原来是由不同子体系的叠氮基α-N和B原子相连而形成的环状结构。几何参数的比较分析还发现N_α-B、N_α-N_β、N_β-N_Υ和B-Cl的键长与聚合度密切相关,环状构型中B-N_α-B键角总比N_α-B-N_α大。同时计算所有优化构型的振动频率,将其IR谱归类.通过热力学计算,发现簇合物的稳定性为3A>3B;4A>4B.由焓变可知,从单体形成二聚体于热力学不利,而形成最稳定三聚体和四聚体的温度分别达800K和500K仍是有利的.     

苯烷基化合成1,2-二苯乙烷反应的热力学研究

利用Excel强大的计算功能,用热力学方法计算和分析了二氯乙烷与苯反应生成二苯乙烷的反应,建立了反应焓变和自由能变化与反应温度的关系方程。计算表明,该反应为强放热反应且反应的Gibbs自由能变化远远小于0;反应温度及苯与二氯乙烷物质的量的比,对平衡转化率的影响不明显;一般应将反应温度控制在60℃～75℃,以保证一定的反应速度;将n苯/n二氯乙烷控制在(5-7):1范围,以保证1,2-二苯乙烷的高选择性。     

GPR109A同源建模及其与吡唑类激动剂对接模拟

烟酸受体G偶联蛋白受体109A(GPR109A)是心血管疾病和脂代谢紊乱等疾病治疗的重要靶点蛋白,但因属于膜蛋白,其晶体结构一直未被解析,给药物设计带来极大挑战。本文基于鼠类PUMA-G晶体结构,采用同源模建的方法构建GPR109A蛋白三维结构,运用Ramachandran Plot和Profile-3D对模型进行评估,通过加力场,加膜,loop等方法对模型进行优化,得到蛋白最优模型,并计算分析得到其12个可能的活性位点。利用SYBYL-X2软件构建GPR109A的吡唑类激动剂药物小分子,通过最陡下降法和共轭梯度法得到药物小分子的最稳定构象。用Libdock方法将激动剂对接至蛋白各活性位点,获得二者作用模型。我们分析各活性位点氨基酸分布情况,并以3-羧酸5-甲基吡唑为参考分子探讨药物与各蛋白活性位点相互作用情况。本实验对设计G偶联蛋白受体109A吡唑类激动剂有理论指导意义。     

山梨醇与对甲基苯甲醛合成山梨醇缩醛反应的热力学分析

分析和计算山梨醇与对甲基苯甲醛合成山梨醇缩醛反应的热力学对于开发该反应的催化剂和反应工艺具有重要意义。首次利用Benson法计算了山梨醇一缩对甲基苯甲醛(MPBS)、山梨醇二缩对甲基苯甲醛(DPBS)和山梨醇三缩对甲基苯甲醛(TPBS)的热力学参数,建立了MPBS、DPBS和TPBS的热容与温度的关系方程。在此基础上,利用Kirchhoff方程,分别建立了山梨醇与对甲基苯甲醛缩合为MPBS、DPBS和TPBS 3个反应的焓变与温度的关系方程,计算表明在300 K～1000 K温度范围内,山梨醇与对甲基苯甲醛缩合生成MPBS、DPBS和TPBS的3个反应均为放热反应。     

脂肪族聚酰胺振动光谱的密度泛函理论研究

采用密度泛函理论DFT-B3LYP方法,在6-31G基组水平上对3种脂肪族聚酰胺尼龙2(PA2),尼龙4(PA4)和尼龙6 (PA6)的低聚物OA2,OA4和OA6构型进行优化,得到基态稳定构型;在优化构型基础上计算了分子振动谐性力场,并对理论谐性力场进行了简正坐标分析,得到了低聚物红外光谱及拉曼光谱,用标度因子0.96对计算频率校正。对照实验值,根据振动模式对其特征峰进行了指认。并讨论了由不同长度亚甲基链组成的聚酰胺对振动光谱的影响。     

Calculation of the vibrational contribution to the Gibbs energy of formation for Al3Sc

The ground-state energies were calculated for the stoichiometric compound Al₃Sc in the L1₂ structure, and its constituents (fcc-Al and hcp-Sc) using the Vienna ab initio simulation package (VASP). The enthalpy of formation for Al₃Sc at 0 K was obtained. On the basis of the calculated equation of state (EOS) at 0 K, the vibrational contribution to the Gibbs energy of formation at finite temperatures was estimated using the Mean-Field Potential (MFP) method, and compared with the phonon spectrum calculation and the existing CALPHAD assessments. The calculated entropy of formation can serve as a reasonable start value in a CALPHAD assessment although it is not as accurate as the enthalpy of formation calculated at 0 K. Both high-temperature x-ray scattering measurements and first-principles calculation show that Al₃Sc is almost perfectly ordered up to its melting point and thus the configurational contribution can be neglected.     

吡嗪类硝基衍生物结构与爆轰性能的DFT研究

采用B3LYP/6-311++G**方法对26种硝基吡嗪类衍生物体系进行了全优化,几何优化结果表明所有优化后的化合物结构均无虚频,为势能面上的稳定结构;采用Monte-Carlo方法理论估算了26种化合物的密度,随着硝基数目的增加,密度增加;并设计等键等电子反应计算了其生成焓及其热力学性质,硝基数目逐渐增加时,Cp、S...     

Thermodynamic reassessment of the Ag–Cu phase diagram at nano-scale

The Ag–Cu phase diagram at nanoscale was reassessed by CALculation of PHAse Diagrams (CALPHAD) method, considering the surface effect on the chemical potential of pure substance and excess Gibbs free energy of mixtures. According to the reported thermodynamic properties of pure Ag and Cu nanoparticles (NPs), and the measured melting eutectic temperatures of Ag₈Cu₂, Ag₇Cu₃, Ag₆Cu₅ to Ag₅Cu₅ NPs, respectively, obtained in the previous works, self-consistent thermodynamic parameters including the size effect were obtained by thermodynamic optimization. Using the obtained thermodynamic parameters, four Ag–Cu nano phase diagrams were constructed, and thermodynamic properties were calculated. It was indicated that the calculated Ag–Cu nano phase diagrams agreed well with experimental data.     

软件集成环境下的精馏塔动态仿真

化工过程动态仿真的关键问题是物性数据的计算及非线性微分方程和代数方程的求解，商品化的过程稳态模拟软件能够精确计算纯组分及混合物的物性，而MATLAB/SIMULINK具有强大计算及仿真功能。该文通过将Matlab／Simulink与Aspen Plus模拟软件物性和热力学数据库集成，对精馏塔进行了动态仿真研究。文中阐述了软件集成的方法，建立了精馏塔的通用动态数学模型，在Simulink中以S-函数的方式进行了实现。通过软件集成进行过程的仿真研究，充分利用了现有软件的优势，减少了编程工作量，提高了开发效率。     

A thermodynamic assessment of the Cr–Mo system using CE-CVM

A thermodynamic assessment of the condensed phase region of the Cr–Mo system has been carried out on the basis of available experimental thermodynamic and phase equilibria data. The Gibbs energy of the BCC_A2 solid phase was described by using octahedron–rhombohedron–cube (ORC) approximation of the Cluster Expansion and Cluster Variation Methods (CE-CVM), while a sub-regular solution model was used for describing Gibbs energy of the liquid phase. An optimal set of parameters has been obtained for describing the Gibbs energies of the liquid and solid phases in the Cr–Mo binary system by simultaneous optimization of all experimental data. The calculated phase diagram and thermodynamic properties are in good agreement with experimental data. The relevance of CE-CVM has been demonstrated in the present case by computing first to fifth neighbor short range order (sro) parameters of the solid phase as a function of composition at various temperatures.     

A new implementation of common matrix approach using third-order tensors for face recognition

In the classical common matrix approach (CMA), the common matrix for each individual face class is obtained using basis matrices calculated by Gram–Schmidt orthogonalization of the class covariance matrix. This common matrix represents the common or invariant properties of a given face class. The CMA idea relies on the concept of basis matrices of a face class which span the, so called, difference subspace of that class. In this paper, an alternative method to obtain the basis matrices for CMA is proposed. The basis matrices are obtained using the higher order singular value decomposition (HOSVD) of a third-order tensor constructed with face images and these basis matrices are utilized in the construction of CMA. In order to exemplify the improvements in the recognition rates, face recognition experiments are carried out via the AR face database. The original face matrices, as well as 2DPCA-, 2DSVD-, and 2DFDA-based feature matrices are applied as the input matrices for the two different implementations of CMA in the experimental studies. The results indicate that the recognition rates obtained by the proposed method are slightly higher than those obtained using the basis matrices calculated by Gram–Schmidt orthogonalization.