Fe-exchanged fluorotetrasilicic mica as an active and reusable catalyst for Michael reaction

Fe³⁺-exchanged fluorotetrasilicic mica acts as a highly effective and reusable catalyst for the solventless Michael reaction of β-ketoesters with vinyl ketones under mild condition. The immobilized catalyst shows higher activity than homogeneous Fe³⁺ catalysts, FeCl₃·6H₂O and Fe(NO₃)₃·9H₂O.     

均一沉淀法云母片被覆TiO2

利用硫酸氧钛和的均一沉淀反应法，在天然矿物云母上被覆ＴｉＯ２薄膜，讨论了薄膜形成主影响膜层结构的工艺因素，分阶段控制反应温度和时间有利于控制析出粒子形态和膜最，可获得均匀致密切的膜，不同厚度的膜层因光学干涉效应显示出各种色彩。     

The influence of composition and fine structure on a thermographical characteristics of micas

Several isomorphic groups of micas: Muscovite-Phengite-Muscovite-Li-Muscovite; Biotite-Zinnwaldite-Lepidolite and Biotite-Phlogopite were investigated by DTA, TG and DTG. Octehedral vacancies and the sites of octahedral cationic occupancy were determined from IR-spectra of the hydroxyls. The influence of a composition and fine structure of the micas on the shape of the thermal curves was discussed. A one to one correspondence between the isomorphic series members and individual thermal curves makes it possible to determine the chemical composition of a mica sample. The combination of thermal and IR-spectra of hydroxyl analyses permits to link the Order-Disorder data with thermal properties of mica. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday     

Raman Scattering and X-Ray Diffraction Studies on Alkali-Metal Intercalated Clays

Abstract

Vermiculite and fluor-tetrasilicic mica were intercalated with alkali metals (Na, K and Rb) by vapor transport. X-ray and Raman scattering experiments were conducted to study the structure and lattice dynamics of the new clay compounds. When Rb and K atoms were intercalated to the host materials, superlattices were formed. In Na intercalated compounds, however, no superlattice x-ray diffraction peaks were found. Raman spectra exhibited drastic changes after alkali-metal intercalation, reflecting the structural changes found by our x-ray diffraction.     

St/BA/KH-570三元共聚物的合成及其在云母增强聚丙烯中的应用

通过原子转移自由基聚合反应，合成了苯乙烯，丙烯酸丁酯和3－甲基丙烯酰氧基丙基三甲氧基硅烷的三元共聚物，发现该共聚合体系是一“活性”／受控聚合体系，三元共聚物的结构通过红外光变和核磁共振得以确认。研究了该三元共聚物作为大分子偶联剂对云母增强聚丙烯力学性能的影响。发现三元共聚物的组成和分子量对云母增强聚丙烯的力学性能有较大影响。     

Thermally‐activated post‐growth dewetting of fullerene C60 on mica

Understanding and controlling the growth and stability of molecular thin films on solid surfaces is necessary to develop nanomaterials with well‐defined physical properties. As a prominent model system in organic electronics, we investigate the post‐growth dewetting kinetics of the fullerene C₆₀ on mica with real‐time and in situ X‐ray scattering. After layer‐by‐layer growth of C₆₀, we find a thermally‐activated post‐growth dewetting, where the smooth C₆₀‐layer breaks up into islands. This clearly shows that growth is kinetically limited before the system moves over an activation barrier into an energetically favored configuration. From the temperature‐dependent dewetting kinetics we find an effective activation barrier of 0.33 eV, which describes both the temperature‐dependent macroscopic changes in the surface morphology and the microscopic processes of inter‐ and intralayer diffusion during dewetting.

     

Vibrational spectra and analyses of MFe(CO)4 (M = Cd,Hg)

The IR and Raman spectra of the compounds CdFe(CO)₄ and HgFe(CO)₄, are reported and assigned using C_2v, local symmetry around the iron atom; vibrational analyses of the spectra have also been carried out. The spectroscopic data obtained indicate that the compounds are probably polymers with a centre of symmetry and an octahedral configuration about the iron atom in accordance with X-ray structural results.     

Adsorption of polymers with crown ether substituents on muscovite mica

Ultrahigh specific surface area muscovite with different ions at the surface (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ca²⁺, Sr²⁺, Ba²⁺, Cu²⁺) was treated with aqueous solutions of low molecular weight crown ethers and polymers with crown ether substituents. The adsorption was assessed by UV analysis of the supernatant solution, and with TGA and IR spectroscopy of the mica solids. In contrast to other layered silicates, the low molecular weight crown ethers show no affinity to any of the muscovite surfaces. The polymers can adsorb, however, depending on the type of surface cation. The results indicate that at least some of the crown ether moieties are complexed to surface cations and that the diameter of the ions at the surface plays an important role in the adsorption process.     

Photochemistry of 5-aryl-2(3H)-furanones. : A new route to the synthesis of chromones

The photochemistry of 5-phenyl-, 5-(2',5'-dimethoxyphenyl)-, 5-(2'-acetoxy-5'-methoxyphenyl)- and 5- (2',5'-diacetoxyphenyl)- 2(3H)-furanone (1a-d) has been investigated. Compound 1a yields phenyl vinyl ketone as expected. Similarly, 1b affords the corresponding aryl vinyl ketone but, in this case, photodimerization also occurs. Irradiation of the two o-acetoxyaryl furanones 1c and 1d gives rise to the formation of chromones as the main products. This interesting result can be accounted for in terms of a photochemical opening of the lactonic ring followed by radical addition to the acetoxy group.