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101.
Water soluble conducting polyaniline with electrical conductivity of 10~(-1)-10~(-2) S/cm was prepared employingdopant induced water solubility technology. The water resistance of the conducting film was significantly improvedemploying sol-gel hybrids method, especially when the conductive polyaniline loading was below 30 wt%. The reason forthe improvement is that the conducting polyaniline chains are confined in a stable inorganic network. 相似文献
102.
Tietze LF Bell HP Chandrasekhar S 《Angewandte Chemie (International ed. in English)》2003,42(34):3996-4028
Natural products play an important role in the development of drugs, especially for the treatment of infections and cancer, as well as immunosuppressive compounds. However, the number of natural products is limited, whereas millions of hybrids as combinations of parts of different natural products can be prepared. This new approach seems to be very promising in the development of leads for both medicinal and agrochemical applications, as the biological activity of several new hybrids exceeds that of the parent compounds. The advantage of this concept over a combinatorial chemistry approach is the high diversity and the inherent biological activity of the hybrids. 相似文献
103.
Li-min?Zhao Bing?YanEmail author Qian-ming?Wang 《Monatshefte für Chemie / Chemical Monthly》2005,136(9):1545-1551
Summary. A kind of precursor molecule (abbreviated as EPDA–APMS) was synthesized by means of the amidation reaction of 5-ethylpyridine-2,3-dicarboxylic acid (EPDA) with a crosslinking molecule (3-aminopropyl)trimethoxysilane (APMS). Then the hybrid materials were obtained by reaction of this kind of monomer (EPDA–APMS), tetraethoxysilane (TEOS) and Tb(NO3)3·6H2O by an in-situ sol-gel process, resulting in a novel molecular hybrid material (named as Tb–EPDA–APMS) with double chemical bonds (Tb–O coordination bond and Si–O covalent bond). Ultraviolet absorption, phosphorescence, and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb3+ substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb3+. 相似文献
104.
Reactions of lead(II) acetate with m-aminobenzenesulfonic acid (HL1) and 5-sulfoisophthalic acid (H3L2) afforded two new lead(II) sulfonates, Pb(L1)21 and Pb2(L2)(μ3-OH)(H2O) 2. In compound 1, the lead(II) ion is eight-coordinated by two sulfonate groups bidentately, two sulfonate groups unidentately and two amino groups from six ligands. Each L1 ligand is tetradentate and bridges with three Pb(II) ions. The interconnection of the Pb(II) ions via bridging sulfonate ligands resulted in 〈100〉 and 〈200〉 layers. In compound 2, one Pb(II) ion is six-coordinated by a carboxylate group bidentately, by two carboxylate groups unidentately, by a sulfonate oxygen atom and by an OH anion, whereas the other one is six-coordinated by a bidentate chelating carboxylate group, two μ3-OH anions, a sulfonate oxygen atom and an aqua ligand. The interconnection of irregular PbO6 polyhedra via carboxylate-sulfonate ligands resulted in the formation of a pillared layered structure with the 2D layer being formed; the lead(II) ions, hydroxyl groups, carboxylate and sulfonate groups and the benzene ring as the pillar agent. 相似文献
105.
L. Hou H. Schmidt B. Hoffmann M. Mennig 《Journal of Sol-Gel Science and Technology》1997,8(1-3):927-929
Organic-inorganic hybrid materials synthesized via sol-gel processing are excellent solid matrices for photochromic dyes like
spirooxazine, and the photochromic performance can be further enhanced by introducing suitable additives. This work describes
the effects of additives on the photochromic intensity (ΔA
0), decolouration rate (k) and photostability of spirooxazine in sol-gel derived organic-inorganic hybrid matrices. They include fluoroalkylsilane
(FAS), bisphenolA (BPA) and methyl-imidazole (MI). FAS enhances both ΔA
0 and photostability, but has little effect onk. The higher the content of BPA, the higher the ΔA
0 and the higher the photostability, but the lower thek. The effect of MI on ΔA
0 andk is not so considerable as that of BPA and is a little complicated, while significant improvement in photostability is achieved
by the addition of MI at an optimum concentration with the presence of BPA at a higher content. 相似文献
106.
Helena M. Carapuça M. Salete Balula Ana Paula Fonseca Ana M. V. Cavaleiro 《Journal of Solid State Electrochemistry》2006,10(1):10-17
It has been demonstrated, for the first time, that an adsorbed single-layer of the hybrid salts (TBA)4H3PW11O39, (TBA)4PW11Fe(H2O)O39, (TBA)4PW11Mn(H2O)O39 and (TBA)4HPW11Co(H2O)O39 can be fabricated on the surface of a glassy carbon electrode by the droplet evaporation methodology. These chemically modified electrodes were stable and their preparation was reproducible and easy to perform. The electrochemical features of the immobilized polyanions were different from those of the corresponding soluble species, namely in what concerns the peak potential values. The effect of the scan rate and of pH on the voltammetric features led to the conclusion that the first W reduction process for all immobilized polyanions was diffusion-controlled. For TBA-PW11, TBA-PW11Fe and TBA-PW11Co the two-electron reductions at the first W waves are accompanied by the uptake of protons (2 H+ for the PW11 anion and 4 H+ for the Fe-substituted and Co-substituted species). For the PW11Mn-modified electrode, the reduction at the first W wave was a 1 e/2 H+ process. Additionally, the results obtained in the presence of Na2SO4 in the solution highlighted the role of the ions in the supporting electrolyte in the redox features of the immobilized hybrid phosphotungstates. 相似文献
107.
K. H. Wu T. C. Chang Y. T. Wang Y. S. Chiu 《Journal of polymer science. Part A, Polymer chemistry》1999,37(13):2275-2284
Poly(imide–silica) hybrid materials with covalent bonds were prepared by (3-aminopropyl)methyldiethoxysilane (APrMDEOS) terminated amic acid, water, and tetramethoxysilane (TMOS) via a sol–gel technique. Infrared (IR), 29Si and 13C CP/MAS nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA) were used to study hybrids containing various proportions of TMOS and hydrolysis ratios. The microstructure and chain mobility of hybrids were investigated by proton spin–spin relaxation T2 measurements. The apparent activation energy Ea for degradation of hybrids in air was studied by the van Krevelen method. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2275–2284, 1999 相似文献
108.
P. Hajji L. David J. F. Gerard J. P. Pascault G. Vigier 《Journal of Polymer Science.Polymer Physics》1999,37(22):3172-3187
Two types of polymer–silica nanocomposites have been prepared by undergoing free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) either in the presence of HEMA-functionalized SiO2 nanoparticles (Type 1) or during the simultaneous in situ growing of the silica phase through the acid-catalyzed sol–gel polymerization of tetraethoxysilane (TEOS) (Type 2). Relationships between synthesis conditions, chemical structure, and resulting morphology have been studied. Type 1 systems exhibit a classical particle-matrix morphology, but where particles tend to form aggregates. Type 2 systems possess a finer morphology characterized by a very open mass-fractal silicate structure, which is believed to be bicontinuous with the organic phase at a molecular level. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3172–3187, 1999 相似文献
109.
EXAFS, SAXS and Eu3+ Luminescence Spectroscopy of Sol-Gel Derived Siloxane-Polyethyleneoxide Hybrids
C. Molina S.J.L. Ribeiro K. Dahmouche C.V. Santilli A.F. Craievich 《Journal of Sol-Gel Science and Technology》2000,19(1-3):615-620
Hybrid Eu3+-doped silica-poliethyleneoxide (PEO) nanocomposites with covalent bonds between the inorganic (siloxane) and organic (PEO) phases have been obtained by sol-gel process. These materials are transparent, flexible and present high Eu3+ luminescence output. Their luminescence properties, local environment around europium ions and structure have been investigated as a function of europium content. EXAFS measurements indicate that the increase in Eu-doping induces a decrease in Eu3+ coordination number. An increase in symmetry degree around the metal ion is also observed for increasing Eu3+ concentration, while non radiative decay paths from the 5D0 excited state become more important. SAXS results suggest the preferential interaction of europium ions with ether-type oxygens of the polymer chains. However, the existence of interactions between the cations and the carbonyl groups from urea bridges located at the siloxane-PEO interface can not be excluded. 相似文献
110.
K. Noble A.B. Seddon M.L. Turner P. Chevalier I.A. Mackinnon 《Journal of Sol-Gel Science and Technology》2000,19(1-3):807-810
We report the preparation of polysiloxane-modified mesoporous silica gels derived from the acid catalysed hydrolysis of tetraethoxysilane (TEOS) and oligomeric silanol terminated polydimethylsiloxane (PDMS) in the presence of the non-ionic surfactant, octaethylene glycol monohexadecyl ether. The gels were characterised using thermal gravimetric analysis (TGA), infra-red (IR) spectroscopy, X-ray diffraction (XRD) and 29Si solid state cross-polarisation (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. TGA and IR spectroscopy showed the loss of surfactant after calcination and a decrease in the Si–OH band at 950 cm–1 indicated further condensation had occurred. This was confirmed by the increase in Q4 at –110 ppm, in 29Si MAS NMR spectroscopy, which also showed that calcination had led to the redistribution of PDMS forming a T species. XRD data showed ordering within the structure, with an initial d-spacing of 45 Å, decreasing to 35 Å after calcination. 相似文献