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 共查询到19条相似文献,搜索用时 125 毫秒
1.
报道了罗格列酮二甲双胍加合物(Rosiglitazone metformin adduct)的合成,红外和晶体结构,罗格列酮二甲双胍加合物属于单斜晶系,空间群为P-1,晶胞参数:a=0.6967(2)nm,b=1.1282(3)nm,c=1.7208(5)nm.α=72.374(6)°,β=81.835(6)°,γ=74.140(6)°,晶胞体积V=1.2374(6)nm3,晶胞内分子数Z=2.罗格列酮与二甲双胍之间的氢键为N(6)-H(6B)…O(2)(-x+1,-y,-z+1):0.2893(7)nm,N(8)-H(8C)…N(1)(-x+2,-y,-z+1):0.2951(7)nm,N(7)-H(7B)…O(1) (x-1,y,z):0.2883(6)nm,晶态下分子间以氢键作用力和范德华力维系其空间稳定性,罗格列酮分子内无氢键,二甲双胍分子内及分子间均有氢键联系.  相似文献   

2.
在4,4’-二硫联吡啶在Au表面形成自组装单分子层膜的基础上,采用表面增强拉曼散射光谱(SERS)研究了在不同pH值条件下金纳米粒子在4,4’-二硫联吡啶自组装单分子膜/Au体系表面的组装。研究结果表明,由于处于单分子膜表面的吡啶环中氮原子的质子化程度随溶液环境中pH值的变化而变化,使得金纳米粒子与单分子膜表面间的结合作用程度不同,由此会引起金纳米粒子在单分子膜表面的覆盖度存在差异,并最终导致所观测到的4-巯基吡啶自组装单分子膜的SERS光谱强度存在明显的差异。而且,令人感兴趣的是,所观测到的SERS谱峰强度随金纳米粒子组装时pH值的变化呈现出明显的规律性。结合分子结构特征的分析,初步阐明了SERS谱峰强度随pH值这一组装条件的改变而发生规律性变化的内在原因。  相似文献   

3.
花生酸与铈β-二酮络合物混合单分子膜的成膜特性   总被引:3,自引:0,他引:3  
将铈 β 二酮络合物 (Ce(tmhd) 4)的氯仿溶液与花生酸 (AA)的氯仿溶液以不同摩尔比混合并铺展在纯水亚相上 ,得到其与AA的混合单分子膜 .对混合单分子膜的成膜特性 (π A等温线和体系超额自由能 )进行了探讨 ,发现混合单分子膜的超额自由能为负值 ,混合过程为热力学自发过程 ,且在配比为 1∶2时其绝对值最大 ,体系最稳定 ,并进一步讨论了混合单分子膜可能的凝聚态结构 .在配比为 1∶2时 ,研究了混合单分子膜的静态弹性和动态弹性  相似文献   

4.
运用分子轨道理论中的半经验AM1、PM 3方法和Hartree Fock从头算方法 ,通过能量梯度全优化率先计算了新近合成的化合物N ,N 二 (8 羟基 5 喹啉甲基 )甘氨酸乙酯的平衡几何构型、电子结构以及生成热、偶极矩等分子基本性质 ,并联系经典有机电子结构理论进行讨论。三种方法得到的结构参数基本一致 ,和实验测量的晶体结构符合较好。在稳定构型基础上 ,用AM1方法进行正则振动频率分析 ,得到C—C双键、C—N单双键、C—O单双键和羟基OH的振动基频 ,和实验测得的红外光谱特征峰吻合较好  相似文献   

5.
花生酸与柿β—二酮络合物混合单分子膜的成膜特性   总被引:1,自引:0,他引:1  
将β-二酮络合物(Ce(tmhd)4)的氯仿溶液与花生酸(AA)的氯仿溶液以不同摩尔比混合并铺展在纯水亚相上,得到其与AA的混合单分子膜.对混合单分子膜的成膜特性(π-A等温线和体系超额自由能)进行了探讨,发现混合单分子膜的超额自由能为负值,混合过程为热力学自发过程,且在配比为1:2时其绝对值最大,体系最稳定,并进一步讨论了混合单分子膜可能的凝聚态结构.在配比为1:2时,研究了混合单分子膜的静态弹性和动态弹性。  相似文献   

6.
通过π-A曲线(π:膜对浮片所施之力,A:单分子所占的面积)研究浓度、pH值、温度以及蔗糖对磷脂酰乙醇胺相变的影响.实验表明:(1)当浓度较高时,磷脂酰乙醇胺的π-A曲线随着浓度的增加重合性较好,平均分子面积和表面膜压有较好的对应.当浓度较低时,π-A曲线重合性较差,在低密度情况下,磷脂酰乙醇胺分子的排列不紧密,致使分子的随机运动对膜压的影响较大;(2)亚相处于较强的酸性或者碱性状态下均会使磷脂酰乙醇胺分子的相变变慢,pH值过高或过低都会对膜有较大的破坏作用;(3)当温度逐渐增大,而保持平均分子面积不变时,随着温度的增加,t-pa曲线(温度-膜压)逐渐由一条直线变成抛物线,这说明随着温度的增加磷脂酰乙醇胺凝聚膜会向液态扩张膜转变,即随着温度的增加相变延迟;(4)蔗糖对磷脂酰乙醇胺单分子膜有较强的稳定作用,且这种作用在生理条件下最为明显.用原子力显微镜直接观测了不同压力下转移至云母表面分子层的形貌特征,进一步解释了磷脂酰乙醇胺单分子膜相变的微观分子机制.  相似文献   

7.
张兆慧  李海鹏  韩奎 《物理学报》2013,62(15):158701-158701
采用分子动力学方法, 模拟了由脂肪酸CnH2n+1COOH和C17H35COOH (n=12,13,14,15,16,17) 按1:1比例组成的7种混合单层Langmuir-Blodgett (LB)膜和由C16H33COOH 分子组成的单层膜的摩擦性质. 结果显示: 1) 随着混合单层膜内的不同分子链长差的减小, 其剪切压随之减小, 摩擦力主要来自单层膜间的库伦作用; 2) 混合膜内的两种不同分子的尾基排列对其摩擦性能影响较大, 当混合LB膜中所有分子尾基全同排列时剪切压较小. 当分子链长差为1 个C-C键长时, 分子尾基排列对膜的摩擦性质影响较大. 3) 同种分子尾基全同排列组成的单层膜, 当上下两单层膜的尾基呈镜面对称时, 其剪切压随着分子链长的增加而减小, 摩擦力主要来自膜间的库伦作用; 当上下两单层膜的尾基呈中心对称时, 膜间摩擦力主要来自膜间的范德华 (VDW) 作用. 关键词: 分子动力学模拟 纳米摩擦 薄膜 库伦能  相似文献   

8.
合成了一种新型两亲分子4-甲基-5-羟乙基-噻唑-十八酸酯(以下简写为HISE),利用FTIR,^1H NMR,MS等手段对其进行了表征,并研究了在不同pH值的亚相溶液中HISE单分子膜的形成,通过表面压-分子面积等温线(π-A)的测定,发现随着亚相pH值的增加,单分子膜的崩溃压升高,HISE的成膜性能逐渐增强,单分子膜从膨胀型向压缩型转变。通过对微分曲线dπ/dA-A的分析,研究了不同pH值的亚相中HISE单分子膜的不可压缩性和相变过程。结果表明,碱性介质中HISE单分子膜具有良好的稳定性和不可压缩性。  相似文献   

9.
王克东  李斌  杨金龙  侯建国 《物理》2006,35(3):188-192
通过将单个C59N分子置于双势垒隧道结中,从而利用单电子隧穿效应和C59N分子的特殊能级结构,我们成功地实现了一种新型的单分子整流器件.实验中这个整流器件的正向导通电压约为0.5-0.7V,反向击穿电压约为1.6—1.8V.理论分析表明,中性C59N分子的半占据费米能级以及在不同充电情况下费米能级的不对称移动是形成整流效应的主要原因.其构成原理也决定了该器件具有稳定、易重复的特点.  相似文献   

10.
在B3LYP/6-311+G(d,p)水平上研究了2-(1H-咪唑)苯硫酚(1d)、2-(噁唑)苯硫酚(2d)、2-(噻唑)苯硫酚(3d)及其衍生物的基态质子转移过程,探讨取代基电子效应对质子转移的影响.结果表明:吸电子引入后分子平面电子密度减小,N2-H1间距减小,分子内氢键增强,醇式到酮式质子转移能垒减小;供电子基引入后分子平面电子密度增大,N2-H1间距增大,分子内氢键减弱,质子转移能垒增大.Localized orbital locator(LOL)分析表明:取代基的引入对N1原子成键性质产生影响明显.三者质子转移能垒大小为1d3d2d,取代基引后能垒相对大小不变.  相似文献   

11.
采用水溶液均聚合方法,制备了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AMC14AB)的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P(AMC14AB)在水溶液中的胶束化行为与表面吸附现象. 在水溶液中,均聚物P(AMC14AB)呈现单分子链胶束的聚集形态,具有零临界胶束浓度,从开始加入P(AMC14AB)起,水溶液中随即产生单分子链胶束,不存在Krafft温度. P(AMC14AB)在溶液表面也发生表面吸附,使水的表面张力下降,即P(AMC14AB)也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达饱和时,表面张力~浓度曲线上出现突变点,该点定义为饱和的表面吸附浓度,而不应该再称为临界胶束浓度. P(AMC14AB)单分子链胶束溶液对疏水有机物(甲苯)的增溶情况,明显不同于普通小分子表面活性剂十六烷基溴化铵(CTAB)的多分子胶束溶液,甲苯增溶量~P(AMC14AB)浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液.  相似文献   

12.
Pesticide residue in vegetables has been considered as a serious food safety problem across the whole world. This study investigates a novel advanced oxidation process (AOP), namely the coupled free chlorine/ultrasound (FC/US) process for the removal of three typical pesticides from lettuce. The removal efficiencies of dimethoate (DMT), trichlorfon (TCF) and carbofuran (CBF) from lettuce reached 86.7%, 79.8% and 71.3%, respectively by the FC/US process. There existed a synergistic effect in the coupled FC/US process for pesticide removal and the synergistic factors reached 22.3%, 19.0% and 36.4% for DMT, TCF and CBF, respectively. Based on the analysis of mass balance of pesticides, the synergistic effect was probably attributed to the efficient oxidation of pesticides both in vegetables and in water by the generated free radicals and FC. The surface area and surface structure of vegetables strongly affected the removal of pesticides by FC/US. The removal efficiency of DMT increased from 80.9% to 88.1% as solution pH increased from 5.0 to 8.0, and then decreased to 84.1% when solution pH further increased to 9.0. When the ultrasonic frequency changed from 20 to 40 kHz, a remarkable improvement in pesticide removal by FC/US was observed. As the FC concentration increased from 0 to 15 mg L–l, the removal efficiencies of pesticides increased firstly, and then became stagnant when the FC concentration further increased to 25 mg L–l. The pesticide degradation pathways based on the identified intermediates were proposed. The total chlorophyll content was reduced by less than 5% after the FC/US process, indicating a negligible damage to the quality of vegetables. It suggests that the FC/US process is a promising AOP for pesticides removal from vegetables.  相似文献   

13.
合成了两种末端碳锭长度不同的水杨醛类希夫碱N-十二烷基(2-羟基-5-硝基苯甲亚胺)和N-十六烷基(2-羟基-5-硝基苯甲亚胺),研究了它们在气-液界面上的成膜性能,并通过紫外、荧光、红外显微镜等光谱手段对它们在LB膜上的性能进行了表征。实验结果表明两种希夫碱分子在LB膜中都形成了J-聚体,末端碳链较长的希夫碱 成膜性能相对较好,并且在膜上也能光致发光,但希夫碱分子的LB膜存在一定的缺陷。  相似文献   

14.
We use combined ab initio molecular dynamics (AIMD), grand canonical Monte Carlo, and molecular dynamics techniques to study the effect of pore surface chemistry and confinement on the permeation of salt into silica nanopore arrays filled with water. AIMD shows that 11.6 A diameter hydroxylated silica pores are relatively stable in water, whereas amine groups on functionalized pore surfaces abstract silanol protons, turning into NH3+. Free energy calculations using an ab initio parametrized force field show that the hydroxylated pores strongly attract Na+ and repel Cl- ions. Pores lined with NH3+ have the reverse surface charge polarity. Finally, studies of ions in carbon nanotubes suggest that hydration of Cl- is more strongly frustrated by pure confinement effects than Na+.  相似文献   

15.
We report studies on temperature, field and time dependence of magnetization on cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles show unusual features in comparison to other antiferromagnetic nanoparticle systems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves bifurcate well above the Néel temperature and the usual peak in the ZFC magnetization curve is absent. The system does not show any memory effects which is in sharp contrast to the usual behavior shown by other antiferromagnetic nanoparticles. It turns out that the non-equilibrium behavior of CuO nanoparticles is very strange and is neither superparamagnetic nor spin glass like.  相似文献   

16.
17.
Superparamagnetic iron oxide (SPIO) nanoparticles show great promise for many biotechnological applications. This paper addresses the synthesis and characterization of SPIO nanoparticles grafted with three different alkoxysilanes: 3-aminopropyl-triethoxysilane (APTES), 3-aminopropyl-ethyl-diethoxysilane (APDES) and 3-aminopropyl-diethy-ethoxysilane (APES). SPIO nanoparticles with an average particle diameter of 10 nm were prepared by chemical sonoprecipitation. As confirmed by Fourier transform infrared (FTIR) spectroscopy, silylation of these nanoparticles occurs through a two-step process. Decreasing the number of alkoxide groups reduced the concentration of free amino groups on the SPIO surface ([SPIO-NH2]—APTES>APDES>APES). This phenomenon results from steric contributions and the formation of H-bonded amines provided by the ethyl groups present in the APDES and APES molecules. A simulation of SPIO nanoparticles in a saline physiologic solution shows that the ethyl groups impart larger steric stability onto the ferrofluids, which reduces aggregation. The magnetization (M) versus magnetic field (H) curves show that the synthesized iron oxide nanoparticles display superparamagnetic behavior. The zero-field cooling (ZFC) and field cooling (FC) curves show that the changes in the blocking temperature depend on the alkoxysilane-functionalized particle surface.  相似文献   

18.
Based on a recursive Green's function method, we investigate the conductance of mesoscopic graphene rings in the presence of disorder, in the limit of phase coherent transport. Two models of disorder are considered: edge disorder and surface disorder. Our simulations show that the conductance decreases exponentially with the edge disorder and the surface disorder. In the presence of flux, a clear Aharonov-Bohm conductance oscillation with the period Φ0 (Φ0=h/e) is observed. The edge disorder and the surface disorder have no effect on the period of AB oscillation. The amplitudes of AB oscillations vary with gate voltage and flux, which is consistent with the previous results. Additionally, ballistic rectification and negative differential resistance are observed in I-V curves, with on/off characteristic.  相似文献   

19.
Low-energy deposition of neutral Pd(N) clusters (N=2-7 and 13) on a MgO(001) surface F center (FC) was studied by spin-density-functional molecular dynamics simulations. The incident clusters are steered by an attractive "funnel" created by the FC, resulting in adsorption of the cluster, with one of its atoms bonded atop of the FC. The deposited Pd2-Pd6 clusters retain their gas-phase structures, while for N>6 surface-commensurate isomers are energetically more favorable. Adsorbed clusters with N>3 are found to remain magnetic at the surface.  相似文献   

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