一种基于胆固醇的荧光小分子胶凝剂的合成及其胶凝行为

合成并表征了一种含7-硝基苯并-2-氧杂-1,3-二唑基(7-Nitrobenzo-2-oxa-1,3-diazol-4-yl)的胆固醇衍生物(NBD-C), 考察了其在30种溶剂中的胶凝行为. 实验结果表明, NBD-C对乙腈具有很强的胶凝作用, 且该凝胶体系具有显著的剪切触变性. 对干凝胶的显微分析发现, 在不同溶剂中, NBD-C具有不同的聚集结构. 红外光谱(FTIR)、核磁共振光谱(¹H NMR)和荧光光谱研究结果表明, 除了胆固醇的范德华堆积作用之外, 分子间氢键作用也是该化合物聚集的重要驱动力.     

Novel dimeric cholesteryl-based A(LS)2 low-molecular-mass gelators with a benzene ring in the linker

Three novel dimeric cholesteryl-based A(LS)(2) low-molecular-mass organic gelators (LMOGs) with phthaloyl, isophthaloyl, or terephthaloyl moieties in the linkers were designed and prepared. According to the linker structures, the compounds are denoted as 1 (o-), 2 (m-), and 3 (p-), respectively. Gelation tests revealed that the difference of relative positions of two cholesterol moieties in the benzene ring can produce a dramatic change in the gelation behaviors of the compounds. Importantly, 2 and 3 are more efficient gelators than 1, and their self-assembly behaviors are also very different from each other as revealed by scanning electron microscopy (SEM) measurements. Very interestingly, 2 gels xylene spontaneously at room temperature, and the sol-gel phase transition of the system is mechanically controllable. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding and pi-pi interactions between the molecules of the gelators play an important role in the formation and maintenance of the gels. The X-ray diffraction (XRD) analysis revealed that in the gel of 2/benzene, 2 aggregated into a layered structure with an interlayer distance of 3.54 nm, which is just the length of 2.     

Structures and solvatochromic phosphorescence of dicationic terpyridyl-platinum(II) complexes with foldable oligo(ortho-phenyleneethynylene) bridging ligands

A series of binuclear organoplatinum(II) complexes, [(tBu3tpy)Pt--(C[triple chemical bond]C--1,2-C6H4)n--C[triple chemical bond]C--Pt(tBu3tpy)][ClO4]2 (1-7, n=1, 2, 3, 4, 5, 6, 8; tBu3tpy=4,4',4'-tri-tert-butyl-2,2':6',2'-terpyridine) with foldable oligo(ortho-phenyleneethynylene) linkers were prepared and characterized by spectroscopic methods and/or X-ray crystallographic analyses. In the crystal structures of 32.5 CH3OH, 5CH3CN, and 64 CH3CN, each of the bridging ortho-phenyleneethynylene ligands has a partially folded conformation. In aerated water/acetonitrile mixtures with water percentages larger than 40 %, the emission of complexes 3-7 are red-shifted and enhanced when compared to those recorded in acetonitrile. The red-shift in emission energy and enhanced emission intensity can be attributed to the inter- and/or intramolecular interactions induced by the addition of water to solutions of the platinum(II) complexes in acetonitrile. Data from dynamic light scattering and transmission electron microscopy studies revealed that these binuclear platinum(II) complexes aggregated into nanosized particles in acetonitrile/water mixtures. Hydrophobic folding of the ortho-phenyleneethynylene linkers in acetonitrile/water mixtures is postulated.     

带极性侧链的环[6]芳酰胺的球形自组装

环芳酰胺是一类基于三中心氢键促进,经寡聚前体一步大环合成法得到的刚性大环分子.通过紫外-可见(UV-Vis)光谱、动态光散射(DLS)、扫描电镜(SEM)、透射电镜(TEM)和原子力显微镜(AFM)等实验手段,详细考察了侧链为三甘醇单甲基醚链,由六个苯环单元组成的环[6]芳酰胺的自组装行为.实验结果表明,该大环在1,2-二氯乙烷中发生自组装,其组装聚集体随温度升高产生从聚集体到单分子的解聚变化,至70℃时几乎完全解聚;在由良溶剂(二氯甲烷)和不良溶剂(芳烃类)组成的混合溶剂中,带有三甘醇醚链的环[6]芳酰胺化合物1自组装成微球,结合热稳定性实验和TEM证实是实心微球而非囊泡.进一步发现微球形成和形貌依赖于混合溶剂中不良溶剂的极性和种类,芳烃类溶剂有利于微球形成,而烷烃和极性溶剂则不利,后者更倾向于形成膜的结构.     

Unsaturation effect on gelation behavior of aryl glycolipids

Structurally simple, renewable-resource-based cardanyl (glucoside)s [1, 1-O-3'-n-(pentadecyl) phenyl-beta-D-glucopyranoside; 2, 1-O-3'-n-(8'(Z)-pentadeceenyl)-beta-glucopyranoside; 3, 1-O-3'-n-(8'(Z),11'(Z)pentadecadienyl)phenyl-beta-D-glucopyranoside, 4; 1-O-3'-n-(8'(Z),11'(Z),14'-pentadecatrienyl)phenyl-beta-D-glucopyranoside; and the mixture 5] form thermally reversible transparent gels in a water/alcohol mixture and a number of organic solvents, strongly influenced by the unsaturation of the aliphatic alkyl chain. DSC studies revealed that the Tgel of 1 in water/ethanol (1:1, vol/vol) gel is 69.0 degrees C, while of the introduction of a single double bond reduces the value to 30.0 degrees C in the case of monoene 2, indicating that the stability of the gel is related to the number of double bonds on the lipophilic part of the gelator. Furthermore, XRD measurements showed that the aqueous gel 1 maintains an interdigitated bilayered structure with 3.14 nm long-range ordering, and the corresponding organogel maintains an extended bilayer structure for 4.34 nm, indicating a clear difference in the aggregation behavior in different solvents.     

A novel low-molecular-mass gelator with a redox active ferrocenyl group: tuning gel formation by oxidation

A novel low-molecular-mass gelator containing a redox-active ferrocenyl group, cholesteryl glycinate ferrocenoylamide (CGF), was intentionally designed and prepared. It was demonstrated that the gelator gels 13 out of the 45 solvents tested. Scanning electron microscopy (SEM) measurements revealed that the gelator self-assembled into different supramolecular network structures in different gels. Chemical oxidation of the ferrocenyl residue resulted in phase transition of the gel from gel state to solution state. FTIR and (1)H NMR spectroscopy studies revealed that hydrogen bonding between the gelator molecules in the gel was one of the main driving forces for the formation of the gels.     

Screening of mucoadhesive microparticles containing hydroxypropyl-beta-cyclodextrin for the nasal delivery of risperidone

Interaction of the antipsychotic drug risperidone with hydroxypropyl-beta-cyclodextrin (HPBCD) in solution and in the solid state was studied with the aim of overcoming the limitations associated with nasal administration of low solubility drugs. Risperidone solubility studies revealed inclusion complex formation with a 1:1 stoichiometry. Low concentrations (0.1 w/v %) of hydroxypropylmethyl cellulose (HPMC) and carbomer affected risperidone solubility in water. No formation of a ternary complex was detected. The solid inclusion complex was prepared by spray drying and was characterised by thermal (DSC) and spectral (FTIR) analyses. Risperidone and the inclusion complex were loaded into microparticles by spray drying using HPMC, carbomer and HPMC/carbomer interpolymer complex (IPC) as mucoadhesive components. The microparticles were characterised with respect to drug loading, particle size distribution, thermal analysis, and zeta potential measurements. Mucoadhesive properties of the microparticles were studied by measuring the work of adhesion. Carbomer and IPC based microparticles revealed superior mucoadhesive microparticles compared to HPMC based microparticles. Drug incorporation into microparticles reduced their mucoadhesive properties, while incorporation of the cyclodextrin complex caused no additional reduction in mucoadhesion. The in vitro dissolution studies showed that formation of the inclusion complex significantly increased the risperidone dissolution rate from the microparticles, thus providing sustained drug release.     

Creation of Functional Organic Gels Based on Oligothiophenes

Polymer gels have received a great deal of attention not only from scientific interest but also for their practical applications. Recently, low molecular-weight organic gels have also been receiving growing attention. However, their have been few studies of low molecular-weight organic gels in contrast to extensive studies of polymer gels. In order to develop a novel class of low-molecular-weight organic gels and to gain an insight into the relationship between molecular structures of gel-form…     

Synthesis of Porous PEG Microgels Using CaCO3 Microspheres as Hard Templates

Porous poly(ethylene glycol) (PEG) microgels of both 17.6 and 8.3 μm in diameter are synthesized via hard templating with calcium carbonate (CaCO₃) microparticles. The synthesis is performed in three steps: loading of PEG macromonomers into CaCO₃ microparticles, crosslinking via photopolymerization, and removal of the CaCO₃ template under acidic conditions. The resulting porous PEG microgels are inverse replicates of their templates as indicated by light microscopy, cryo‐scanning electron microscopy (cryo‐SEM), and permeability studies. Thus this process allows for the straightforward and highly reproducible synthesis of porous hydrogel particles of two different diameters and porosities that show great potential as carriers for drugs or nanomaterials.     

Amphiphilic azobenzenesulfonic acid anionic surfactant for water-soluble, ordered, and luminescent polypyrrole nanospheres

Self-organized micelles of new renewable resource amphiphilic azobenzenesulfonic acid anionic surfactant were utilized to prepare water-soluble, luminescent, and highly ordered polypyrrole nanomaterials. The micellar behavior of the reaction medium was precisely controlled by varying the composition of pyrrole/surfactant ratio from 3 to 100 (up to 100 times lower amount of surfactant with respect to pyrrole), and polypyrrole nanospheres of 150-800 nm were prepared. Dynamic light scattering (DLS) and viscosity techniques were employed as tools to trace the factors, which control the mechanism of polypyrrole nanomaterials formation. DLS studies confirmed that the surfactant exists as in the form of spherical micelles of 4.8 nm diameter in water. Specific viscosity measurement revealed that the pyrrole+surfactant complexes in water exist in the form of either aggregated or isolated micelles depending upon their composition in the feed. SEM and TEM analysis confirmed that the aggregated micellar templates produced coral-like morphology, whereas uniform polypyrrole nanospheres of 150-400 nm were obtained at low micellar concentration. The nanomaterials formation was unperturbed by the variation of the oxidation agents such as ammonium persulphate (APS) or ferric chloride (FeCl3). WXRD analysis of the nanomaterials indicates that the anionic surfactant effectively penetrates into the polypyrrole chains, and a new peak at 2theta = 6.3 degrees (d-spacing = 14 A) was observed corresponding to highly ordered polymer chains. UV-vis and FT-IR confirmed the highly doped state, and the conductivity of the samples was obtained in the range of 10(-1) to 10(-2) S/cm by four-probe conductivity measurements. The azobenzenesulfonic acid anionic surfactant is luminescent in water, and its grafting on the polypyrrole nanospheres enhances the luminescent intensity with the quantum yield in the range of 2 x 10(-3) to 3 x 10(-4).     

Self-assembling molecular trees containing octa-p-phenylene: from nanocrystals to nanocapsules

Tree-shaped molecules consisting of octa-p-phenylene as a stem segment and oligoether dendrons as a flexible head were synthesized and characterized. The molecular tree based on a small flexible head self-assembles into a lamellar structure, whereas the molecule based on a larger headgroup self-assembles into a discrete heptameric bundle that organizes into a 3-D primitive orthorhombic supercrystals, as confirmed by X-ray scatterings and transmission electron microscopic (TEM) observations. Optical studies revealed that the absorption and emission maxima and absorption edge of the 3-D structure shift to higher energy compared to those of the lamellar structure. The molecules in dilute solution (THF/water = 1:10 v/v) were observed to self-assemble into capsule-like hollow aggregates, as confirmed by dynamic and static light scatterings, scanning electron microscopy (SEM), and TEM investigations. These results demonstrate that tree-shaped molecules are capable of packing into organized discrete nanocrystals with parallel arrangement as well as hollow nanocapsules with radial arrangement, depending on the presence of selective solvents for flexible headgroup.     

Phagocytosis of PLGA microparticles in rat peritoneal exudate cells: a time-dependent study.

With the purpose of enhancing the efficacy of microparticle-encapsulated therapeutic agents, in this study we evaluated the phagocytic ability of rat peritoneal exudate cells and the preferential location of poly(d,l-lactide-co-glycolic acid) (PLGA) microparticles inside these cells. The microparticles used were produced by a solvent evaporation method and were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Size distribution analysis using DLS and SEM showed that the particles were spherical, with diameters falling between 0.5 and 1.5 mum. Results from cell adhesion by SEM assay, indicated that the PLGA microparticles are not toxic to cells and do not cause any distinct damage to them as confirmed by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. Among the large variety of cell populations found in the peritoneal exudates (neutrophils, eosinophils, monocytes, and macrophages), TEM showed that only the latter phagocytosed PLGA microparticles, in a time-dependent manner. The results obtained indicate that the microparticles studied show merits as possible carriers of drugs for intracellular delivery.     

单分散二氧化硅球形颗粒的制备与形成机理

在醇水混合溶剂中以氨作催化剂，正硅酸乙酯为硅源，通过溶胶—凝胶工艺制 备单分散二氧化硅球形颗粒，通过透视电镜进行研究各种反应条件如溶剂类型、氨 和水的浓度、水解温度等对二氧化硅的颗粒大小和形貌的影响．结果显示：以甲醇 和乙醇为溶剂可以形成单分散的二氧化硅球形颗粒，以丙醇和丁醇为溶剂，二氧化 硅球形颗粒容易聚集；在其它条件不变的情况下，球形颗粒的粒径随水和硅源的浓 度增加而增大；而且水解温度的升高，生成的颗粒粒径也逐渐增大，仔细研究和讨 论了二氧化硅颗粒在不同反应条件下的形成机理．     

Porphyrin-based organogels: control of the aggregation mode by a pyridine-carboxylic acid interaction

To find a new strategy for designing porphyrin-based organogelators, hydrogen-bond-donating (carboxylic acid)/accepting (pyridine) substituents or electron-donating (dialkylamino)/withdrawing (pyridine) substituents were introduced into peripheral positions of a porphyrin (1cp or 1ep, respectively), and the gelation properties were compared with those of symmetrical reference compounds bearing two pyridyl substituents or two ester groups (1pp or 1ee, respectively). It was found that the symmetrical molecules show a solubility that is quite inferior to that of 1cp and 1ep having a dipole moment and precipitate from most organic solvents. 1cp, 1ep, and 1ee formed gels with cyclohexane, methylcyclohexane, and several alcoholic solvents, but scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that their superstructures constructed in the organogels are very different. In cyclohexane, 1cp resulted in a sheetlike structure, whereas 1ep and 1ee resulted in a fiberlike structure. The difference is attributed to the two-dimensional interactive forces in 1cp consisting of the porphyrin-porphyrin pi-pi stacking and the carboxylic acid-pyridine hydrogen bonding. In fact, when the hydrogen-bonding interaction was weakened by alcoholic solvents or by adding pyridine or N,N-(dimethylamino)pyridine, the sheetlike structure was transfigured to the fiberlike structure. Further detailed analyses of their aggregation modes were conducted by spectroscopic methods such as ultraviolet-visible (UV-vis) absorption, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD). On the basis of these findings, the influence of these peripheral substituents on the gel formation and the aggregation mode was discussed.     

Synthesis and aggregation study of tin nanoparticles and colloids obtained by chemical liquid deposition

Tin colloids (Sn-Colls) and nanoparticles were synthesized by a chemical liquid deposition method (CLD). Sn⁰ was evaporated and codeposited with acetone, 2-propanol, and tetrahydrofurane vapors at 77 K to obtain colloidal dispersions. Sn-Coll were characterized by UV spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy, selected area electron diffraction, thermal analysis, infrared spectroscopy [Fourier transform infrared (FTIR)], and light scattering. TEM micrographs of tin nanoparticles (Sn-Nps) revealed a particle size distribution between 2 and 4 nm for the three solvents used in the synthesis. UV studies showed strong absorption bands in the UV region, suggesting that the Sn-Nps obtained by CLD exhibit quantum confinement and typical bands of plasmons corresponded to aggregated particles. Electrophoresis measurement indicated a significant tendency of particle aggregation along time, which was verified by light scattering studies. The diffraction patterns revealed phases corresponding to metallic tin and FTIR studies showed the interaction Sn-solvent in the metal surface by Sn-O bonds, indicating a solvatation of metallic clusters. Thermal analysis revealed a good thermal stability of Sn-Nps. The mechanism of tin nanoparticles formation was also examined.     

混合溶剂对溶胶-凝胶法制备的Li3V2(PO4)3/C高倍率性能的影响

以有机-水为混合溶剂, 采用溶胶-凝胶法制备锂离子电池正极材料Li₃V₂(PO₄)₃/C, 选取乙醇、乙二醇和1,2-丙二醇为有机溶剂, 聚丙烯酸(PAA)为碳源和螯合剂. 通过X射线衍射(XRD)、扫描电镜(SEM)、恒流充放电以及循环伏安测试等方法, 研究了产物的结构形貌及电化学性能. XRD测试结果表明所有溶剂制备的样品结晶良好, 有机溶剂的加入不影响Li₃V₂(PO₄)₃材料的晶型结构. 恒流充放电结果表明有机溶剂的加入改善了材料的电化学性能. 以1,2-丙二醇-水为溶剂的样品电化学性能最好, 在3.0-4.5 V电压范围内, 0.1C (1C=150 mA·g^-1)倍率首次放电比容量为132.89 mAh·g^-1, 10C倍率首次放电比容量达125.42 mAh·g^-1, 循环700周后容量保持率为95.79%, 具有良好的倍率性能与循环性能; 在3.0-4.8 V电压范围内倍率性能较差. 扫描电镜结果表明混合溶剂制备的样品呈片状和针状, 这种形状有利于锂离子的扩散, 因此提高了材料的电化学性能.     

Cholesteryl derivatives as phase-selective gelators at room temperature

One cholesterol-based ALS and two dimeric cholesterol-based A(LS)₂ low-molecular-mass organic gelators (LMOGs) containing phthaloyl, isophthaloyl, and terephthaloyl moieties, respectively, were prepared. Gelation test revealed that 2 and 3 are more efficient gelators than 1. Interestingly, 2 and 3 can gel several solvents spontaneously at room temperature and these gels posses thixotropic properties as revealed by rheological studies. More interestingly, 2 and 3 show selective gelation of the solvents from their mixtures with water. The network structures of some gels were investigated by SEM measurements, and the molecular packing mode of the LMOGs in the gel was studied by XRD analysis. Temperature- and concentration-dependent ¹H NMR measurements revealed that hydrogen bonding between the gelator molecules is an important driving force for the gel formation.     

Particle self-assembly in oil-in-ionic liquid Pickering emulsions

We have studied polydimethylsiloxane (PDMS)-in-1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) Pickering emulsions stabilized by polystyrene microparticles with different surface chemistry. Surprisingly, in contrast to the consensus originating from oil/water Pickering emulsions in which the solid particles equilibrate at the oil-water droplet interfaces and provide effective stabilization, here the polystyrene microparticles treated with sulfate, aldehyde sulfate, or carboxylate dissociable groups mostly formed monolayer bridges among the oil droplets rather than residing at the oil-ionic liquid interfaces. The bridge formation inhibited individual droplet-droplet coalescence; however, due to low density and large volume (thus the buoyant effect), the aggregated oil droplets actually promoted oil/ionic liquid phase separation and distressed emulsion stability. Systems with binary heterogeneous polystyrene microparticles exhibited similar, even enhanced (in terms of surface chemistry dependence), bridging phenomenon in the PDMS-in-[BMIM][PF(6)] Pickering emulsions.     

三维有序大孔α-Fe2O3的制备及电化学性能研究

通过聚苯乙烯(PS)胶晶模板法合成了三维有序大孔(3DOM) α-Fe2O3, 运用扫描电镜、热重分析、X射线衍射、电化学充放电等多种方法对其结构和性能进行了表征和研究. SEM表明PS 胶晶模板和3DOM α-Fe2O3呈周期性排列. 合成的3DOM α-Fe2O3为三维有序多孔网状结构, 具有球型和六边形的孔隙形貌, 其孔径大小约为(115±10) nm; 孔壁由α-Fe2O3纳米晶粒组成, 壁厚为20～30 nm. XRD图谱表明经过煅烧除去模板后, 形成了纯α-Fe2O3相. 当3DOM α-Fe2O3作为锂离子电池负极材料时, 首次放电充电容量分别高达1880和1130 mAh•g－1, 20次循环后可逆容量依然高达631 mAh•g－1, 库仑效率大于90%.     

作为锂离子电池负极材料的三维有序大孔SnO2的 制备及表征

通过聚苯乙烯(PS)胶晶模板法合成了三维有序大孔(3DOM) SnO2. 运用扫描电镜、热重分析、X射线衍射、电化学充放电等多种方法对其结构和性能进行了表征和研究. SEM图表明PS胶晶模板微球排列规整, 大小均匀(直径275±10 nm), 形成多层六方紧密堆积排列; 煅烧除去模板后的3DOM SnO2呈三维多孔网络结构, 具有圆型和六边形的孔隙形貌, 其孔径大小为(215±10) nm; 孔壁由SnO2纳米晶粒组成, 壁厚为20～30 nm. XRD图谱表明经过煅烧除去模板后, 形成了纯SnO2相. 当作为锂离子电池负极材料时, 3DOM SnO2表现出较好的充放电容量和库仑效率. 此外, 这种合成方法简单、经济, 可进一步应用于其它锂离子电池材料的合成.