β-环糊精与荧光黄的包合作用

制备了以β-环糊精为主体,荧光黄为客体的晶体包合物,用红外光谱、DSC曲线、荧光光谱、共振瑞利散射光谱等方法确定了包合物的形成,对包合物的形成进行了初步讨论,并用Hildebrand-Benesi双倒数法测定了包合物的包合常数.实验结果表明:β-环糊精与荧光黄分子形成包合比为1:1的包合物.     

阿维菌素包合物的红外光谱研究

依据β-环糊精的分子空腔容纳性质,利用饱和水溶液法制备出阿维菌素-β-环糊精包合物,利用高效液相色谱法测定其包封率。 结合红外光谱谱图说明了阿维菌素-β-环糊精包合物的形成;分析了阿维菌素光解所产生的化学结构变化;研究了所形成的包合物增强阿维菌素化学结构光稳定性的效应。 结果表明：阿维菌素-β-环糊精包合物的包封率为40.5%;从红外光谱谱图分析,说明阿维菌素-β-环糊精包合物形成了分子间氢键,组合效应与其物理混合物有区别。 阿维菌素B1a分子大环内酯结构可以被光分解破坏,分解后大环内酯结构中的C—O—C结构红外伸缩振动峰消失,内酯键发生明显断裂。 形成阿维菌素-β-环糊精包合物后,β-环糊精起包合作用的分子位点覆盖了阿维菌素B1a分子大环内酯结构,为阿维菌素B1a分子大环内酯结构中的C—O—C结构提供良好的避光保护作用,提高了阿维菌素B1a分子的光稳定性。 本实验的创新之处在于对所制备的阿维菌素-β-环糊精包合物的结构和特性从红外光谱角度进行了分析,此类包合物可望作为理想的阿维菌素保护型控释制剂中间体。     

Preparation and Spectroscopic Study of Different Stoichiometric Solid Supramolecular Inclusion Complexes of β-Cyclodextrin with Short Chain Aliphatic Amines

选择β-CD为主体,制备了它与乙二胺1、二乙烯三胺2和三乙胺3形成的固体包合物,并通过元素分析、X射线衍射、红外光谱、热重和1H核磁共振等物理手段对制备的包合物进行了表征．基于元素分析和1H核磁共振的结果,在1-β-CD、2-β-CD和3-fi-CD三个固体包合物中,主体、客体的化学计量比分别确定为2:5、1:1和3:1．包合物的产率与客体分子对β-CD空腔的体积比有关,提升顺序为1-β-CD<2-β-CD<3-β-CD．X射线衍射表明,由于β-CD与客体存在分子间相互作用,原本归属于主、客体的衍射峰不仅在峰的位置,而且在峰的形状和衍射强度上都发生了明显的变化．并且主、客体包合物的形成明显提高了被包合的客体分子1和3的相变温度．此外,位于β-CD空腔小口端的H-5质子由于包合作用而显示更大的化学位移变化,而所有腔外质子均具有相对较低的化学位移变化值．     

柚皮素/β-环糊精超分子体系的包合行为

本文采用超声法制备了柚皮素（NAR）与β-环糊精（βCD）的包合物.粉末-X射线衍射（XRD）和红外吸收光谱（IR）测定均表明形成的包合物具有不同于主客体的新的结构性质.¹H NMR与ROESY核磁共振（NMR）实验表明NAR以苯环端从βCD的宽口端进入，并形成稳定的超分子包合物.量子化学计算分析NAR/βCD包合物的形成过程表明，驱动力源于焓驱动与氢键弱相互作用力；能隙和结合能分析得到的最优包合模式与NMR研究结果一致；ONIOM分层计算验证了上述结果.分子对接模拟出的最优包合模式也与量子化学计算、NMR的分析结果吻合.本文获取了清晰的NAR/βCD包合物构型及其形成机理，为该超分子药物的定量构效关系研究提供了理论参考.     

PVP对Nylon 6形貌及结晶行为影响的研究

采用变温红外光谱、示差扫描量热（DSC）和偏光显微镜（POM）等方法研究了聚乙烯吡咯烷酮（PVP）与尼龙6（nylon 6）分子间的相互作用及其对nylon 6热行为及结晶形貌的影响。DSC结果表明PVP的加入明显影响了nylon 6的熔融和结晶行为：随着PVP含量增加,PVP/nylon 6共混物的结晶温度、熔融温度及结晶度均逐渐降低;POM观察显示：随着PVP含量增多,nylon 6的球晶尺寸变小、球晶逐渐变得不完善。变温红外光谱结果表明,无定形PVP分子的羰基能够与nylon 6分子的N—H基团形成新的氢键,部分破坏了nylon 6分子之间的氢键结构,从而阻碍了nylon 6分子的规整排列,使其结晶度降低并导致nylon 6结晶形貌的变化。     

Bi12TiO20纳米粉体的制备及其光吸收特性研究

以钛酸四丁酯和硝酸铋为原料 ,利用化学溶液分解法制备了Bi12 TiO2 0 纳米多晶粉体 .采用XRD和TEM对其结构和形貌进行了表征 .结合热重 差热 (TG DTA)分析 ,探讨了Bi12 TiO2 0 晶相的形成机理 .通过UV Vis漫反射谱的测定 ,研究了Bi12 TiO2 0 纳米晶粉体的光吸收特性 .结果显示 ,从组成为化学计量比的前驱液中可以很容易制得纯Bi12 TiO2 0 纳米晶粉体 ,该Bi12 TiO2 0 纳米晶粉体呈现了在很宽的波长范围内 (5 6 0～ 385nm )对光的吸收的特性 .     

D-樟脑与β-环糊精包合物的结构表征

采用饱和水溶液搅拌法制备β-环糊精(β-CD)/D-樟脑包合物.1H NMR确定了β-CD与D-樟脑形成包合物的化学计量比为1∶1.X-射线衍射图谱和红外光谱图证明D-樟脑和β-CD分子间的相互作用.1H ROESY NMR分析结果说明包合物的结构型式是D-樟脑的二环[2.2.1]-2-庚酮位于β-CD空腔内,其三甲基部分位于β-CD空腔外.通过量子化学计算得到形成β-CD/D-樟脑包合物最低结合能和结构优化状态,氢健的存在证实了上述分析结果的准确性.     

3,3'',5,5''-四甲基联苯胺-β-环糊精包合物的紫外-可见光谱和电化学研究

本文采用紫外-可见光谱和电化学的方法研究了3,3',5,5'-四甲基联苯胺(TMB)和β-环糊精形成超分子包合物后的氧化还原性质,研究结果表明在形成包合物后TMB的氧化还原特性更好,尤其是在有酶参与时更易被氧化.在包合物内的氧化产物组分更单纯,修饰在电极表面也表现出更好的氧化还原活性.     

Fe-MOF电极材料的合成及电性能

通过溶剂热法合成出Fe-MOF材料并进行了XRD表征,结果显示Fe-MOF的XRD衍射峰位置和强度都与已知同类型的MOF结构相似,且没有其他晶相出现;在不同扫描速率下测得的循环伏安具有明显的还原电流峰和氧化电流峰,表现出典型的法拉第氧化还原特性;随着扫描速率的增大,比电容急速下降,Fe-MOF结构可能发生扭曲;500次循环实验结果表明,Fe-MOF比容量没有出现明显的衰减,具有良好的循环寿命.     

辣椒碱与β-环糊精包合物的核磁共振研究

利用核磁共振方法研究了辣椒碱β-环糊精包合物的化学计量比、空间结构信息及其在水溶液中的自扩散系数. 通过测定不同浓度比的辣椒碱和β-环糊精混合溶液的 ¹H NMR数据,绘制Job's曲线,辣椒碱和β-环糊精的Job's曲线均在r=0.5处出现拐点. 同时测定了该包合物的2D ROESY和DOSY谱图,ROESY谱图中NOE交叉信号出现在辣椒碱的H-1~H-8和β-环糊精的H-3′、H-5′、H-6′之间,DOSY测得β-环糊精和辣椒碱形成包合物前后的表观自扩散系数. 结果表明,辣椒碱β-环糊精包合物的主客体分子的化学计量比为1∶1,辣椒碱分子的异丙基端从β-环糊精的宽口端进入疏水腔,其中H-1~H-8部分在空腔内部,包合物的自扩散系数为2.95×10^-10m²/s.     

Solid-State NMR Studies on the Guest Ordering and Dynamics in α,ω-Dibromoalkane/Urea Inclusion Compounds

Solid-state nuclear magnetic resonance (NMR) spectroscopy is utilized to study the molecular behavior of 1,10-dibromodecane and 1,11-dibromoundecane in their urea inclusion compounds. The guest dynamics and conformational order are explored by ¹³C cross polarization magic-angle spinning (CP/MAS) and ¹H MAS NMR spectroscopy which confirm an all-trans conformation of the guest chains. Dynamic ²H NMR experiments are carried out on two guest molecules selectively deuterated at both end groups. A quantitative analysis of the experimental data, obtained from variable-temperature line shape, spin–spin and spin–lattice relaxation measurements, shows that both guest molecules undergo similar motions within the investigated temperature range between 100 and 298 K. The combination of nondegenerate 6-site (or 3-site) rotational jumps and small-angle overall chain wobbling provides an appropriate motional model for the guest motions in these compounds. It is found that the populations of the jump sites exhibit a characteristic temperature dependence, although a discontinuity is missing at the solid–solid phase transition. The same holds for the guest motions which also remain unaffected by the change of the urea lattice structure. Rather, a discontinuity of the guest dynamics at about 30 and 10 degrees above the corresponding solid–solid phase transition is observed for 1,10-dibromodecane and 1,11-dibromoundecane in urea, respectively. Likewise, there is no clear evidence for an odd–even effect due to the change of the guest chain length on the molecular properties of the present inclusion compounds. As a general result, it is concluded that the intermolecular interactions in the present materials are stronger than in n-alkane/urea inclusion compounds. Authors' address: Klaus Müller, Institut für Physikalische Chemie, Universit?t Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany     

Solid state NMR strategies for the structural characterization of new hybrid materials based on the intercalation of nitroxide radicals into CdPS3

The radical cations 2-(3-N-butylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (m-BuPYNN) and 4-(ethylammonium)-2,2,6,6-tetramethylpiperidin-1-oxide (EATEP) are successfully intercalated into the layered host structure of CdPS(3) via ion exchange. The reaction proceeds either directly from ethanolic solutions of the radical iodide salt or via a two-stage process involving first the formation of an intermediate tetramethylammonium intercalate. The resulting materials, which are described by the compositional formula Cd(1-x)PS(3){Rad}(2x), are characterized by chemical analysis, X-ray powder diffraction, bulk susceptibility measurements and EPR spectroscopy. Modern single and double resonance solid state NMR techniques are introduced successfully to study the structural modifications of the host lattice and the details of the intermolecular guest/host interactions. (1)H MAS-NMR spectra reveal substantial differences in the unpaired electron spin density distributions within the radical ions intercalated into the host lattice compared to those obtained for the pure radical ion salts, leading to different bulk magnetic properties. The results of (1)H/(31)P double resonance experiments indicate that the orientation of the guest molecules is dominated by Columbic interactions between the radical cations and the negatively charged cadmium vacancies in the host lattice.     

Theoretical investigation of structures and compositions of double neon-methane clathrate hydrates,depending on gas phase composition and pressure

The region of existence of neon clathrate hydrates is an actual problem of hydrate chemistry. The current work presents theoretical study of the equilibrium formation conditions of pure neon clathrate hydrates and double clathrate hydrates of neon-methane mixture. The structures and properties of double clathrate hydrates were described within the scope of the previously developed molecular clathrate hydrate model that takes into account the influence of guest molecules on the host lattice, interaction of guest molecules between themselves, and the possibility of multiple filling of host lattice cages by guest molecules. The model makes it possible to find an equilibrium state and thermodynamic properties of clathrate hydrates at given values of p and T. In the present work, we considered the properties of double clathrate hydrates in the range of pressures from 0 to 4 kbar at 250 K. The results of modeling have shown that the mass fraction of neon in double clathrate hydrate of Ne and CH₄ mixture of cubic structure I (sI) can reach 26%, and 22.5% in double hydrate of cubic structure II (sII) even at a low methane concentration (1%) in gas phase, at high pressure. It is shown that in double clathrate hydrates of the Ne and CH₄ mixture at high pressures, phase transition sII-sI can occur.     

Pressure dependent incommensuration in Rb-IV

Rb-IV is found to have an incommensurate composite structure, comprising a tetragonal host framework and a simple body-centered tetragonal guest. This does not have the unexpectedly short Rb-Rb distances of the previously reported structure [U. Schwarz et al., Phys. Rev. Lett. 83, 4085 (1999)]. The ratio of the c-axis lattice parameters is strongly pressure dependent and approaches the commensurate value of 5/3 at the transition to phase V. A reversible broadening of the guest structure is observed below 16.5(2) GPa.     

The stabilization of unusual conformers in guest-host systems: Solid-state NMR investigations of 2-methylhexadecane in urea and thiourea

Solid-state nuclear magnetic resonance (NMR) spectroscopy is employed for the first time on urea and thiourea inclusion compounds (UICs and TICs) containing branched alkyl chains. In the present work,²H and¹³C NMR as well as X-ray diffraction studies of two selectively deuterated 2-methylhexadecanes in UIC and TIC are presented. An analysis of the derivedT ₁ data reveals significant differences between UICs and TICs, which can be attributed to differences in the motional features of the guest species. It is found that four different motional contributions have to be considered, namely, chain rotation, chain wobbling,trans-gauche isomerization and methyl group rotation. 2-Methylhexadecane in UIC exists in an almost all-trans conformation (gauche amount not more than 5%) and undergoes fast chain rotation (6-site jump process, activation energyE _A=16.7 kJ/mol). The analysis of the²H NMR spectra of 2-methylhexadecane-1,1′,2-d₇ in urea proves that the branched chain end exists in an eclipsed conformation. TheT ₁ data of 2-methylhexadecane-3-d₂ in thiourea can be reproduced by an overall rotation (E _A=9.8 kJ/mol) and atrans-gauche isomerization with torsional jumps around the C-3-C-4 bond (E _A=11.0 kJ/mol,gauche population=15%). As for the corresponding UIC, the²H NMR spectra of 2-methylhexadecane-1,1′,2-d₇ in TIC can be only explained by the existence of an eclipsed conformation at the branched chain end.     

Anomalous states of the structure of [Rb<Subscript>0.7</Subscript>(NH<Subscript>4</Subscript>)<Subscript>0.3</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript> crystals in the temperature range 4.2–300 K

Crystals of [Rb_0.7(NH₄)_0.3]₂SO₄ solid solutions are studied using x-ray diffractometry in the temperature range 4.2–300 K. No anomalies are revealed in the temperature dependences of the lattice parameters and the volume of the host unit cell. A series of superstructure reflections observed along the basis axes corresponds to the guest lattice formed in the matrix of the host structure. From analyzing the axial ratio of these structures and their temperature dependences, it is concluded that the structure of the crystal has the form of an incommensurate composite. The guest structure of the composite at room temperature can be considered a set of chains that are not correlated along the b direction. In the plane perpendicular to the chain axes, these chains form a regular framework that is also incommensurate to the host lattice.     

核磁共振氢谱中二苯基乙二胺衍生物手性识别其结构类似物

本文通过手性二苯基乙二胺与异氰酸酯的衍生化反应,合成了一种C₂对称的手性主体1.该主体可以手性识别其结构类似物：α-苯乙胺（客体2）、α-对甲氧基苯乙胺（客体9）以及它们的衍生物（客体3~8和10~13）.高分辨核磁共振氢谱（¹H NMR）显示了对映体识别中主客体间的氢键作用.结果表明,除含2个NO₂的客体7和12外,主体1可以较易识别含有两个伯胺的脲和酰胺衍生物.研究还发现,主体1对脲衍生物2、9比对酰胺衍生物有更强的氢键作用,此外主体1对（R）和（S）-脲衍生物中的CHCH₃基团也有更高的辨识能力.     

花二酸酐与嘧啶衍生物的氢键组装(英文)

用半经验AM1方法对苝二酸酐与嘧啶衍生物的1∶1及1∶2氢键复合物进行理论研究,表明随着氢键数目增多,弱相互作用能变大,主体上的供电基和客体上的吸电基有利于氢键相互作用,氢键导致电子从主体流向客体。用INDO／SCI方法计算配合物的电子光谱,表明其长波吸收峰与主体相比发生兰移,各配合物的长波吸收峰位置相差不大,与实验一致。讨论吸收峰兰移的原因并对电子跃迁进行理论指认,同时得到了配合物的双质子转移势能曲线,给出了相对于N-H键的过渡态和活化能。     

Characterization and catalytic performance of pure and Li2O-doped CuO/CeO2 catalysts

Pure and Li₂O-doped CuO/CeO₂ catalysts calcined at 500 °C were prepared by impregnation method. The catalysts are characterized by DTA, TG-DTG, XRD, IR, TEM, nitrogen adsorption at −196 °C and the catalytic decomposition of hydrogen peroxide at 30 °C.The effects of molar ratio, heat treatment time and the doping on the structural, surface and catalytic properties of nanocrystalline Cu/Ce-mixed oxides system have been studied. It was found that the catalytic activity of ceria-supported copper oxide catalysts increased by increasing both the heat treatment time and dopant content. However, the pure Cu/Ce-mixed oxide solids containing 10 wt.% CuO exhibited the best performance. The characterization results indicated that the higher surface area, the formation of solid solution between copper and cerium oxides, and the high dispersion of copper species on the ceria were responsible for the high catalytic activity of the CuO/CeO₂ catalysts.