含氟芳杂环化合物的研究 7:含氟氮、硫杂二苯并王冠化合物的合成

本文研究了苯环上含强吸电子基的间硝基对氯三氟甲苯1与一些含氮、氧、硫的亲核试剂作用,经桥接、还原、关环,分别合成了含氟氮杂、硫杂王冠化合10牧11;还得到含氟三氮杂庚环化合物9,并对其生成机理进行了探讨,各步产率都较高.     

含氟芳杂环化合物的研究 7:含氟氮、硫杂二苯并王冠化合物的合成

本文研究了苯环上含强吸电子基的间硝基对氯三氟甲苯1与一些含氮、氧、硫的亲核试剂作用,经桥接、还原、关环,分别合成了含氟氮杂、硫杂王冠化合10牧11;还得到含氟三氮杂庚环化合物9,并对其生成机理进行了探讨,各步产率都较高.     

杂环合成中的氮杂Wittig反应

氮杂Wittig反应是杂环化合物的一个新的合成方法.本文阐述了羰基通过叠氮化物和三价膦形成的亚胺基膦的作用, 以氮杂Wittig反应的方式, 合成含氮杂环化合物的进展.     

镁卟啉与氮、氧杂环化合物的相互作用

以镁卟啉为主体化合物,模拟了生物体内常见的氮、氧杂环客体与主体化合物之间的相互作用.研究结果表明:镁卟啉与氮、氧杂环化合物的相互作用引起了镁卟啉中的镁原子与卟吩环不共面,且二面角越小不共面程度越大.自然键轨道(NBO)理论分析表明氮、氧孤对电子和金属镁的空孤对轨道的相互作用对复合物的稳定性贡献很大.使用约化密度梯度(RDG)函数等值面图和散点图可视化分析了配位相互作用和周边氢键作用的位置及强度.概念密度泛函(DFT)理论参数表明所形成的复合物比主体化合物的热力学稳定性小而反应活性高.芳香性计算表明含氧杂环客体与主体的相互作用使复合物中的卟吩环具有反芳香性,而含氮杂环客体与主体的相互作用使复合物中卟吩环呈现区域性芳香性.     

可回收铋配合物催化氮亲核试剂与对醌甲基化物1,6-加成:轻松获得N-杂环取代的不对称三芳基甲烷衍生物（英文）

开发了一种用对醌甲基化物(p-QMs)和各种芳香族N-杂环化合物1,6-氮杂-迈克尔加成合成含氮不对称三芳基甲烷衍生物的方法.这种合成方法具有反应条件温和、催化剂负载量可接受、原子经济性、易于放大的特点,并且能够以中等至优异的产率形成N-杂环取代的不对称三芳基甲烷衍生物.此外,铋催化剂可以重复使用多次而不会损失其活性.     

金催化分子间炔烃的氮烯转移反应合成含氮杂环化合物

含氮杂环是很多天然产物、生物医药活性物种、光电新材料等的重要结构单元,也是有机合成中非常重要的合成子.主要介绍金催化分子间炔烃与氮烯前体的反应,合成多取代氮杂环化合物.在该类反应中,炔烃经金催化剂活化后,与各种不同的氮烯前体反应,以一种高效、快捷的转化模式构建多官能团化的含氮杂环化合物.     

催化柴油中含氮化合物类型分布的气相色谱分析方法

建立了催化柴油馏分中各种含氮化合物类型分布的气相色谱-氮化学发光检测分析方法,考察了色谱条件对各种含氮化合物分离的影响。采用Al2O3柱富集催化柴油中的含氮化合物,辅以气相色谱-质谱检测器以及部分含氮化合物标准样品对某催化柴油中的80多个含氮化合物进行了定性(或归类)。以N,N-二甲基苯胺、三丁基胺、喹啉、吲哚、咔唑作为标准样品,考察了各种含氮化合物在氮化学发光检测器上的响应,以吲哚为参照,各含氮化合物的相对响应因子为0.97～1.07,表明含氮化合物的响应与其类型无关。氮的质量浓度在1.0～600 mg/L范围内,含氮化合物的峰面积与质量浓度有良好的线性响应,线性相关系数达0.998。催化柴油中几种含氮化合物(吲哚、C2-吲哚、咔唑、1-甲基咔唑、1,8-二甲基咔唑)含量测定值的相对标准偏差均小于8%。当信噪比(S/N)为3时,测得咔唑氮的检出限为1.0 mg/L。苯胺、喹啉、吲哚、咔唑等4种含氮化合物的加标回收率为89.5%～99.8%。该方法可用于不同来源和不同加工工艺的柴油馏分中各种含氮化合物类型分布的研究。     

7-(羟甲基)-8-氮杂螺[4.5]癸烷-8-羧酸叔丁酯的合成

以8-氮杂螺[4.5]癸烷-7,9-二酮为原料,通过酰胺还原、N-Boc保护、甲酰化、醛基四步反应还原反应合成得到目标化合物7-(羟甲基)-8-氮杂螺[4.5]癸烷-8-羧酸叔丁酯,总收率29.8％.反应中间体及产物结构经1 H NMR和ESI-MS确证,同时对每步反应条件进行讨论.该研究提供了一种新结构的含氮螺环化合...     

双/三氮杂冠醚化合物的合成及其作为摩擦改进剂的性能研究※

现代汽车工业的发展以及环保法规的日益严格对车用润滑油的性能提出了更高要求, 摩擦改进剂在提高发动机油减摩性能及燃油经济性方面发挥着重要作用. 有机钼化合物作为目前使用最为广泛的摩擦改进剂, 会增加油品热氧化沉积物的生成, 且油品氧化会导致其减摩性能下降. 针对摩擦改进剂所存在的诸如有害元素、灰分及活性吸附位点有限等问题, 设计并合成了两种双/三氮杂冠醚化合物, 将活性氮原子及长链烷基引入冠醚结构中以提高吸附性能和油溶性, 并研究其作为摩擦改进剂的减摩和抗磨性能. 结果表明, 所合成双/三氮杂冠醚能有效降低油品的摩擦系数和磨损率, 其中含有吡啶结构的三氮杂冠醚表现出更优的摩擦学性能, 可使摩擦系数和磨损率相对于基础油分别降低8.8%和42%. 机理分析表明, 所合成的双/三氮杂冠醚化合物能够在钢表面发生不同程度的吸附, 并进一步发生摩擦化学反应形成润滑保护膜, 防止滑动表面微凸体的直接接触进而改善摩擦学性能.     

氮杂大环铈(Ⅲ)配合物与pUC19 DNA的相互作用

以一种1,4,7,10,13,16,19,22,25,28,31-十一氮杂2,5,8,11,14,17,20,23,26,29,32-十一酰基-环三十三烷的衍生物（CYC）为配体,在溶液中和Ce（Ⅲ,M）离子形成氮杂大环铈配合物（M-CYC）作为仿生催化剂,通过紫外光谱法、荧光光谱法和凝胶电泳法研究了M-CYC配合物与DNA的相互作用. 结果表明,M-CYC与小牛胸腺DNA（CT DNA）以嵌插方式相互作用,在pH = 8.16的缓冲体系中,其结合常数K_b = 2.0×10⁴ L/mol. 凝胶电泳结果表明,当自由基捕捉剂存在时,M-CYC可将超螺旋pUC19 DNA切割为缺刻型DNA,其切割方式为水解切割.     

Effect of open metal sites on adsorption of polar and nonpolar molecules in metal-organic framework Cu-BTC

Atomistic grand canonical Monte Carlo simulations were performed in this work to investigate the role of open copper sites of Cu-BTC in affecting the separation of carbon monoxide from binary mixtures containing methane, nitrogen, or hydrogen. Mixtures containing 5%, 50%, or 95% CO were examined. The simulations show that electrostatic interactions between the CO dipole and the partial charges on the metal-organic framework (MOF) atoms dominate the adsorption mechanism. The binary simulations show that Cu-BTC is quite selective for CO over hydrogen and nitrogen for all three mixture compositions at 298 K. The removal of CO from a 5% mixture with methane is slightly enhanced by the electrostatic interactions of CO with the copper sites. However, the pore space of Cu-BTC is large enough to accommodate both molecules at their pure-component loadings, and in general, Cu-BTC exhibits no significant selectivity for CO over methane for the equimolar and 95% mixtures. On the basis of the pure-component and low-concentration behavior of CO, the results indicate that MOFs with open metal sites have the potential for enhancing adsorption separations of molecules of differing polarities, but the pore size relative to the sorbate size will also play a significant role.     

Adsorption of Organic Bases from Aqueous Solutions on Magnesium Oxide

The adsorption of a series of aromatic and heterocyclic nitrogen-containing compounds on the surface of MgO is investigated under static conditions. It was established that the energy of adsorption of organic bases depends linearly on the effective charge of their nitrogen atoms. It was shown that such a correlation can be explained based on the concepts of the predominant electrostatic interactions in an adsorption complex with a hydrogen bond.     

Molecular dynamics simulations of p-tert-butylcalix[4]arene with small guest molecules

Classical molecular dynamics simulations were used to study p-tert-butylcalix[4]arene inclusion compounds with xenon, nitrogen, hydrogen, methane, and sulfur dioxide guest molecules. The calixarene units were taken to be rigid and the intermolecular molecular interactions were modeled as a sum of the van der Waals interactions with parameters from the AMBER force field and electrostatic interactions. Simulations of the high-density alpha phase and low-density beta0 phase of p-tert-butylcalix[4]arene were used to test the force field. The predicted densities of the two phases were found to agree with experimental measurements at 173 K to within 5 %. Simulations were performed with guests placed inside the calixarene cages of the beta0 phase. Guest-host ratios of 1:1 to 1:4 were considered. Changes in the unit-cell volume and density of the phases with the addition of guest molecules and the inclusion energies for the guests were determined. Finally, the dynamics of the guest motion inside the cages were characterized by determining the root-mean-square displacements and velocity autocorrelation functions of the xenon and nitrogen guests.     

Heats of adsorption and adsorption heterogeneity for methane, ethane, and carbon dioxide in MCM-41

We report the adsorption isotherms and the isosteric heats of adsorption of pure methane, ethane, and CO2 and a mixture of methane and CO2 in the periodic mesoporous silica MCM-41 using a multicomponent adsorption calorimeter of the Tian-Calvet type, looking in particular at the degree of heterogeneity in the adsorption of these species. The adsorption of methane and ethane in MCM-41 was found to be essentially homogeneous, while the adsorption of pure CO2 and of CO2 from a CO2/methane mixture was found to be significantly heterogeneous, reflecting the electrostatic interactions between CO2 and the adsorbent.     

氮化SBA-16负载镍基催化剂的制备及其对甲烷二氧化碳重整反应的催化性能

通过软模板法合成了SBA-16分子筛,采用高温氨气氮化的方法使有序介孔硅材料中的氧原子部分被氮原子取代,得到氮化的SBA-16载体(SBA-16-N)。采用满孔浸渍法制备了镍基催化剂,并将制得的Ni/SBA-16和Ni/SBA-16-N催化剂用于甲烷二氧化碳重整反应。通过透射电镜、氮气物理吸附、X射线衍射、X射线光电子能谱和二氧化碳程序升温脱附等手段研究了载体和催化剂的结构,并利用热重分析对反应之后回收催化剂进行了表征。结果表明,高温氮化后的分子筛中掺入了氮元素,增加了载体的碱性,改善了载体对反应气体的吸附活化能力,增强了载体与金属之间的相互作用,从而提高了催化剂的活性和抗积炭性能。     

Role of electrostatic interactions in particle adsorption

The role of the electrostatic double-layer interactions in adsorption of colloid particles at solid/liquid interface was reviewed. The phenomenological formulation of the governing PB equation was presented with the expressions for the pressure tensor enabling one to calculate forces, torques and interaction energies between particles in electrolyte solutions. Then, the limiting analytical results for an isolated double-layer (both spherical and planar) were discussed in relation to the effective surface potential concept. The range of validity of the approximate expression connecting the surface potential and the effective surface potential with surface charge for various electrolytes was estimated. The results for double-layer systems were next presented including the case of two planar double-layers and two dissimilar spherical particles. Limiting solutions for short and long distances as well as for low potentials (linear HHF model) were discussed. The approximate models for calculating interactions of spheres, i.e., the extended Derjaguin summation method and the linear superposition approach (LSA) were also introduced. The results stemming from these models were compared with the exact numerical solution obtained in bispherical coordinate system. Possibilities of describing interactions of nonspherical particles (e.g., spheroids) in terms of the Derjaguin and the equivalent sphere methods were pointed out. In further part of the review the role of these electrostatic interactions in adsorption of colloid particles was discussed. Theoretical predictions were presented enabling a quantitative determination of both the initial adsorption flux for low surface coverages and the surface blocking effects for larger surface coverages. Possibility of bilayer adsorption for dilute electrolytes was mentioned. The theoretical results concerning both the adsorption kinetics and structure formation were then confronted with experimental evidences obtained in the well-defined systems, e.g., the impinging-jet cells and the packed-bed columns of monodisperse spherical particles. The experiments proved that the initial adsorption flux was considerably increased in dilute electrolytes whereas the monolayer coverages were considerably decreased due to lateral interactions among particles. It was then concluded that the good agreement between experimental and theoretical data confirmed the thesis of an essential role of the electrostatic interactions in adsorption phenomena of colloid particles.     

水合物生成条件下甲烷在水中的吸附

采用悬滴法系统地测定了温度274.2 ~ 282.2 K、压力0.1 ~ 10.1 MPa下甲烷/纯水间界面张力。实验结果表明在恒定温度下界面张力随压力的增加而增大。在高压条件下,压力对界面张力有很大的影响。不同温度和压力下计算出的甲烷在水中的表面过剩浓度结果表明,压力越高,温度越低,甲烷在水溶液中的吸附浓度越高。同时,计算出的甲烷在水溶液中的表面吸附自由能结果表明,在水合物生成条件下,甲烷在水中的吸附比298.2 K更容易。     

胺基功能化的炭材料上二氧化碳吸附的密度泛函理论研究

本文利用色散作用校正的密度泛函理论研究了炭材料上含氮官能团对CO₂吸附的作用。通过计算比较了不同含氮官能团炭材料结构片段吸附二氧化碳后的结构参数和能量,由于较强的静电作用和形成弱氢键,含单个苯环的酰胺和吡啶类的吸附剂吸附二氧化碳的作用强于单个苯胺和吡咯类吸附剂。但当增加苯环数时,色散作用主导的吡咯型吸附剂的吸附能力显著增强。以上结果预示着酰胺和吡咯类将是大π体系中具有良好CO₂吸附性能的吸附剂。因而,色散作用在CO₂吸附过程中也占据着重要地位。计算得到的结果与我们之前的实验结果一致,并且将有利于筛选更有效的二氧化碳吸附剂。     

Theoretical ONIOM2 study on pyridine adsorption in the channels and intersection of ZSM-5

The structures of the acid sites in the channels and intersections of H-, Li-, and Na-ZSM-5 (ZSM = zeolite socony mobil) and their interactions with pyridine molecule have been computed by using three corresponding models containing 22 tetrahedral sites. The calculated adsorption energies of pyridine in the intersection regions of H-, Li-, and Na-ZSM-5 are 197.0, 172.5, and 122.3 kJ/mol, respectively, in good agreement with the respective experimental values of 200 +/- 5, 155-195, and 120 kJ/mol, while those in the straight and sinusoidal channels are much smaller (157.9 and 127.6, 152.2 and 149.4, and 150.4 and 109.9 kJ/mol, respectively). These indicate that the most probable adsorption site for pyridine in ZSM-5 is the acidic site located in the intersection region. The structural parameters of the adsorption complexes show that the acidic proton in the three models of H-ZSM-5 has been transferred to the nitrogen of pyridine, while in alkali cation-exchanged ZSM-5, the coordination of the alkali cation to the nitrogen atom of pyridine dominates the overall interaction. In addition, the adsorption complexes were further stabilized by the long-range electrostatic interaction between the positively charged pyridine hydrogen atoms and the negatively charged lattice oxygen atoms of the zeolite framework. In the intersection regions of H-, Li-, and Na-ZSM-5, the coordination energy of the charge-compensating cation to the pyridine nitrogen amounts to 58, 60, and 68% of the total adsorption energy, respectively, while another 42, 40, and 32%, respectively, is due to long-range electrostatic interactions. This indicates that the zeolite lattice framework surrounding the adsorption site has important contributions to the adsorption energy of the pyridine molecule.     

Pnictogen Interactions with Nitrogen Acceptors

Stabilizing nitrogen pnictogen bond interactions were measured using molecular rotors. Intramolecular C=O⋅⋅⋅N interactions were formed in the bond rotation transition states which lowered the rotational barriers and increased the rates of rotation, as measured by EXSY NMR. The pnictogen interaction energies show a very strong correlation with the positive electrostatic potential on nitrogen, which was consistent with a strong electrostatic component. In contrast, the NBO perturbation and pyramidalization analyses show no correlation, suggesting that the orbital-orbital component is minor. The strongest C=O⋅⋅⋅N pnictogen interactions were comparable to C=O⋅⋅⋅C=O interactions and were stronger than C=O⋅⋅⋅Ph interactions, when measured using the same N-phenylimide rotor system. The ability of the nitrogen pnictogen interactions to stabilize transition states and enhance kinetic processes demonstrates their potential in catalysis and reaction design.