Carboxylic Acids from <Emphasis Type="Italic">Phyllanthus urinaria</Emphasis>

Five compounds, terephthalic acid mono-[2-(4-carboxy-phenoxycarbonyl)-vinyl] ester (1), (E)-3-(5′-hydroperoxy-2,2′-dihydroxy[1,1′-biphenyl]-4-yl)-2-propenoic acid (2), 3,4,5-trihydroxybenzoic acid (3), succinic acid (or butanedioic acid) (4), and 2,3,4,5,6-pentahydroxybenzoic acid (5), were isolated from Phyllanthus urinaria. The structures of these compounds were elucidated by means of spectral techniques including IR, MS, and 1D/2D NMR. 1 and 2 are new compounds.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 14–17, January–February, 2005.     

Sol–gel preparation and properties of hydroxypropylcellulose–titania hybrid thin films

Hydroxypropylcellulose (HPC)–titania hybrid thin films were prepared by sol–gel method where titanium tetraisopropoxide Ti(OC₃H₇ ⁱ )₄ was hydrolyzed under acidic conditions in the presence of HPC, followed by dip-coating and drying at 120 °C for 24 h. The viscosity average molecular weight of HPC was 55,000–70,000 or 110,000–150,000, and the TiO₂/(HPC + TiO₂) mass ratio ranged from 0 to 1, which was calculated on the assumption that all Ti(OC₃H₇ ⁱ )₄ is converted into TiO₂. The films were 0.35–1.0 μm thick, transparent in visible region and opaque in ultraviolet (UV) region, where the optical absorption coefficient in UV region increased with increasing titania content. The refractive index increased with increasing titania content, ranging from 1.6 to 1.8 for the hybrid thin films. The pencil hardness increased from 6B to 5H, the durability in hot water significantly increased and the contact angle of water on films increased from 35° to 89° with increasing titania content. Crack-free films could be deposited on organic polymer substrates irrespective of titania or HPC contents, where cracking did not occur at higher HPC contents even when the substrate was bent.     

Study on open tubular capillary affinity liquid chromatography

A novel mode of affinity chromatography (AC) based on an open tubular capillary column (OTAC) is demonstrated. The OTAC column is prepared by immobilizing Cibacron blue F3GA onto the inner surface of a 50-microm-i.d. capillary column. The AC experiment is performed on a capillary electrophoresis instrument by using its pressure system as the driving force. Bovine serum albumin and lysozyme (Lys) are successfully separated with stepwise gradient elution. The relative standard deviation (RSD) for the elution time of the retained Lys is 0.08%, and good repeatability of its peak area and peak height with an RSD value lower than 2.12% for 10 consecutive runs is observed. The loading capacity and detection limit for the retained Lys are approximately 36 ng and 8.6 ng, respectively. It is also found that the amount of protein adsorbed is unaffected by the flow rate of the loading buffer, and OTAC can be used for the fast determination of biopolymers. Some of the advantages of OTAC over conventional modes of open tubular capillary liquid chromatography are that the detection sensitivity and loading capacity of a sample can be greatly improved, because the relatively large inner diameter of the capillary can be adopted and the whole capillary column can be used to adsorb the solute in OTAC.     

一步法合成N-1,3-二羟基丙烷-2-基烷基乙酰胺

以5-氨基烷基-2,2-二甲基-1,3-二噁烷为起始原料, 乙酸酐为酰化剂, 一步法选择性地合成氨基二醇类氨基乙酰化产物N-1,3-二羟基丙烷-2-基烷基乙酰胺. 该方法操作简便, 收率高. 所合成的4个新化合物的结构均经FTIR, ¹H NMR, ¹³C NMR及HRMS确证. N-3-(1,3-二羟基丙烷-2-基)丙基乙酰胺(1a)作为关键的中间体, 可以用于HIV-1 Tat/ PCAF BRD抑制剂4的合成.     

2D层状焦磷酸锰(Ⅱ)[NH4]2[Mn3(P2O7)2(H2O)2]的结构和磁性研究

A two-dimensional layered manganese(Ⅱ) pyrophosphate, [NH₄]₂[Mn₃(P₂O₇)₂(H₂O)₂] (1), has been synthesized hydrothermally. Its structure is determined by single-crystal X-ray diffraction analysis. Its structure is built up by MnO₆ octahedra and P₂O₇ units, with ammonium NH₄⁺ cations residing in the interlayer regions. The manganese pyrophosphate layer consists of infinite chains of cis and trans edge sharing MnO₆ octahedra linked by P₂O₇ units. Magnetic susceptibility measurements show that this compound exhibits ferrimagnetic-like ordering below 3.2 K. Further study shows that there are two possible superexchange pathways via the oxygen anions in Mn²⁺ ions. Owing to the different bridging modes of O^2-, the competition between ferromagnetic interactions and antiferromagnetic interactions in Mn²⁺ ions results in the ferrimagnetic behavior of 1.     

Catalytic Adsorptive Stripping Voltammetry of Germanium(IV) in the Presence of Gallic Acid and Vanadium(IV)‐EDTA

A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO₄ (pH1.6), 6.0×10^?3 mol/L GA, 3.0×10^?3 mol/L V(IV), 4.0×10^?3 mol/L EDTA, an accumulation potential of ?0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10^?11 to 1.0×10^?8 mol/L and the detection limit is 2×10^?11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10^?10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results.     

Influence of the cathodic polarization on the stability of Ti surface in concentrated KOH solutions

The stability of spontaneous thin layers and thin layers formed upon cathodical polarization of Ti in KOH solutions have been studied by potentiostatic and ellipsometric methods. At open circuit potential (OCP) the strongly adherent films, whose thickness depends on the concentration of the KOH solution, were formed. During the cathodic polarization the transformation of these films to weakly adsorbed precipitated layers on the electrode surface was observed. Comparing the theoretically computed curves with the experimental Ψ vs Δ loci measured ellipsometrically, the complex indices of refraction and the thickness of the generated films, from 3.6 to 60 nm in 1 M KOH and from 36 to 105 nm in 5 M KOH (adherent to the electrode surface), were determined. At OCP the rate of film growth increases with increasing the concentration of KOH solution. Cathodic polarizations change the chemical composition and retard the rate of film growth. Based on the ellipsometric and electrochemical data the chemical compositions of the formed films consisted of TiO₂, Ti₂O₃, TiO₂·H₂O, Ti(OH)₃ and TiOOH·nH₂O.     

Fuzzy Symmetries for Linear Molecules and their Molecular Orbitals

In this paper, the fuzzy symmetry of some prototypical linear molecules has been analyzed. The results show that some molecular orbitals (MOs) are less symmetrical but some others are more symmetrical than the molecular skeleton, which the MOs correspond to. The membership functions of space inversion for MOs are closely related to the chemical characteristics of the MOs. Sometimes, although the symmetry of a molecular skeleton is not obvious, however that of some MO is quite obvious. The membership functions of the fuzzy inversion symmetry depend on the choice of the position of the center of inversion. As compared to those of diatomic molecules and linear tri-atomic molecules, the linear polyatomic molecules in which a distinctive fuzzy symmetry of space translation may exist, and thus a significant effect on their properties can be expected.     

Synthesis and characterization of microencapsulated dicyclopentadiene with melamine–formaldehyde resins

Microcapsules containing healing agents have been used to develop the self-healing polymeric composites. These microcapsules must possess special properties such as appropriate strength and stability in surrounding medium. A new series of microcapsules containing dicyclopentadiene (DCPD) with melamine–formaldehyde (MF) resin as shell material were synthesized by in situ polymerization technology. These microcapsules may satisfy the requirements for self-healing polymeric composites. The chemical structure of microcapsule was identified by using Fourier transform infrared (FTIR) spectrometer. The morphology of microcapsule was observed by using optical microscope (OM) and scanning electron microscope. Size distribution and mean diameter of microcapsules were determined with OM. The thermal properties of microcapsules were investigated by using thermogravimetric analysis and differential scanning calorimetry. Additionally, the self-healing efficiency was evaluated. The results indicate that the poly(melamine–formaldehyde) (PMF) microcapsules containing DCPD have been synthesized successfully, and their mean diameters fall in the range of 65.2∼202.0 μm when the adjusting agitation rate varies from 150 to 500 rpm. Increasing the surfactant concentration can decrease the diameters of microcapsules. The prepared microcapsules are thermally stable up to 69 °C. The PMF microcapsules containing DCPD can be applied to polymeric composites to fabricate the self-healing composites.     

Synthesis,crystal structure,electrochemical properties and large optical limiting effect of a novel 3-(E)-ferrocenyl-vinyl-<Emphasis Type="BoldItalic">N</Emphasis>-hexyl carbazole

The novel compound, 3-(E)-ferrocenyl-vinyl-N-hexylcarbazole (FVHC) was first synthesized and fully characterized by elemental analysis, IR, ¹H-NMR, single-crystal X-ray diffraction, ultraviolet (UV) absorption, cyclic voltammograms (CV) and optical limiting (OL) measurements. The result of single crystal X-ray diffraction for the compound reveals that the ferrocenyl and carbazole groups are approximately coplanar, and bridged by double-bond with E configuration, showing that there is a well-delocalized π-electron system in the molecule. The electrochemical investigation indicated that the electron in the FVHC may partially be delocalized over the π-conjugated system and CT process in functionalized carbazole systems. Besides, the compound exhibited strong UV absorption and large optical limiting effect, indicating promising potential applications as useful OL materials.