Towards photoswitchable quadruple hydrogen bonds via a reversible “photolocking” strategy for photocontrolled self-assembly

Developing new photoswitchable noncovalent interaction motifs with controllable bonding affinity is crucial for the construction of photoresponsive supramolecular systems and materials. Here we describe a unique “photolocking” strategy for realizing photoswitchable control of quadruple hydrogen-bonding interactions on the basis of modifying the ureidopyrimidinone (UPy) module with an ortho-ester substituted azobenzene unit as the “photo-lock”. Upon light irradiation, the obtained Azo-UPy motif is capable of unlocking/locking the partial H-bonding sites of the UPy unit, leading to photoswitching between homo- and heteroquadruple hydrogen-bonded dimers, which has been further applied for the fabrication of novel tunable hydrogen bonded supramolecular systems. This “photolocking” strategy appears to be broadly applicable in the rational design and construction of other H-bonding motifs with sufficiently photoswitchable noncovalent interactions.

A photolocking strategy is described to achieve the construction of effectively photoswitchable quadruple hydrogen bonds featuring with photoregulable H-bonding affinities, which is further applied in the photocontrollable H-bonded self-assemblies.     

碳环管的发现与生长机理初探

C60笼状结构的发现，极大地丰富了碳的结构化学，在进一步的研究中又发现了碳纳米管、“巴基葱”等新的结构形式．Chernozatonskil等还研究了碳环管（Tori）的独特结构，并预测其具有特别的电磁性质［1］．最近，我们在实验中观察到了可能具有这种结构的样品的透射电镜（TEM）图像，并由此探讨了它们的生长机理．样品的制备采用电弧法制C60的装置［2］，但是在纯氮气氛中进行，且在作为阳极的石墨棒外缘裹上一层铝箔，实验采用直流电弧，腔内氮气压力75kPa．放电结束后收集阴极碳棒上的沉积物与腔内的烟灰，研磨成细粉后，在稀盐酸中充…     

Paxdaphnidines A and B, novel penta- and tetracyclic alkaloids from Daphniphyllum paxianum

Two novel alkaloids, paxdaphnidine A (1) with a unique pentacyclic skeleton and paxdaphnidine B (2) with an uncommon tetracyclic skeleton, were isolated from the stems and leaves of Daphniphyllum paxianum. Their structures were established by spectral methods, especially two-dimensional NMR techniques ((1)H-(1)H COSY, HSQC, HMBC, and NOESY).     

一类新的手性β-二酮铜(Ⅱ)配合物合成及性质——Ⅰ. (+)双［1-对烷氧基苯基-3-对-(2′-甲基丁氧基)苯基-1，3-丙二酮］合铜(Ⅱ)

本文合成了一类新的含手性基团的β-二酮铜(Ⅱ)配合物，双［1-对烷氧基苯基-3-对-(2′甲基丁氧基)苯基-1，3-丙二酮］合铜(Ⅱ)，经元素分析、红外光谱及比旋光度测定确定了结构。通过偏光显微镜下相变观察及DSC图谱，证实这些配合物没有液晶性，其原因可能在于分子的对称性不好。     

含有Zn4O4簇的开放骨架结构磷酸锌的水热合成与表征

在水热体系中,以1,4-丁二胺为模板剂制备了Zn5(PO4)4·H3N(CH2)4NH3单晶,单晶结构分析表明,该化合物属正交晶系,Pnma空间群,晶胞参数a=1.83440(6)nm,b=1.33034(4)nm,c=0.74497(2)nm,β=90°,V=1.81801(9)nm3,Z=4,Dc=2.912Mg·m-3,最终因子R1=0.0309,wR2=0.0804[I>2σ(I)].结构中的锌和磷均与氧形成四面体配位,该化合物中含有Zn4O4簇,Zn4O4簇与PO4四面体相连,形成了篮子状亚结构基元,该亚结构基元通过氧桥以正反交替的方式相互连接成三维开放骨架结构.     

形象化教学方法在药学专业化学类课程中的应用

In view of the complex knowledge points and some abstract theories of pharmaceutical chemistry courses, the application of visualized teaching methods to present important knowledge points in a vivid way can enhance the teaching effect and stimulate students' interest in learning. Based on the authors' teaching and research work, this article summarizes the application of figurative teaching methods such as metaphor and analogy in inorganic chemistry and medicinal chemistry courses.     

无胺法合成高硅丝光沸石的表征

采用XRD、SEM、FT-IR、MAS NMR等表征手段, 对以氟离子为结构导向剂无胺法合成的高硅丝光沸石进行了表征. 结果表明: 高硅丝光沸石结构属立方晶系, 晶胞参数小于传统低硅丝光沸石, 但b、c值要比相近硅铝比非氟体系合成的丝光沸石样品的大; 样品形貌及粒径与其硅铝比有关, 表明晶化条件对产物形貌及粒径均有影响; 随硅铝比的增大, FT-IR光谱中450、544、1053 cm-1谱带向高频移动, 720 cm-1谱带强度减弱, 表明骨架中铝减少而硅增多; 采用含氟无胺体系合成高硅丝光沸石时基本上不会产生非骨架铝.     

Cyclization of alkenyl radicals in 5- and 6-(pi-Exo)-exo-dig modes: new entry to exo-cyclic dienes

Radical cyclizations of alkenyl iodides in both 5- and 6-(pi-exo)-exo-dig modes were effected by tributyltin hydride and AIBN to give exo-cyclic dienes fused to five- and six-membered rings in good yields.     

Selective detection of dopamine in the presence of ascorbic acid and uric acid by a carbon nanotubes-ionic liquid gel modified electrode

The electrochemistry of dopamine (DA) was studied by cyclic voltammetry at a glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes (MWNTs) and room-temperature ionic liquid of 1-octyl-3-methylimidazolium hexafluorophosphate (OMIMPF₆). The thickness of gel on the surface of the electrode has to be controlled carefully because the charging currents increase with the modified layer being thicker. The anodic peaks of DA, ascorbic acid (AA) and uric acid (UA) in their mixture can be well separated since the peak potential of AA is shifted to more negative values, while that of UA is shifted to more positive values due to the modified electrode. At pH 7.08 the three peaks are separated ca. 0.20 and 0.15 V, respectively; hence DA can be determined in the presence of UA and more than 100 times excess of AA. Under optimum conditions linear calibration graphs were obtained over the DA concentration range 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ M. The detection limit of the current technique was found to be 1.0 × 10⁻⁷ M based on the signal-to-noise ratio of 3. The modified electrode has been successfully applied for the assay of DA in human blood serum. This work provides a simple and easy approach to selectively detect dopamine in the presence of ascorbic acid and uric acid.     

Vibration and X-ray photoelectron spectroscopies of FeCl3-doped poly(p-diethynylbenzene)

The doping mechanism of poly(p-diethynylbenzene), chemically doped with FeCl₃, was investigated. Absorption, infrared, far infrared, Raman, X-ray photoelectron spectroscopies were used to determine the nature of the dopant in doped polymer. The experimental results suggest that the charge transfer reaction between the polymer chain and the dopant results in the formation of FeCl₄⁻ species, the π electron charge delocalization along the polymeric chain and the reduction of π-π^* transition energy.