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991.
A new unsymmetrical photochromic diarylethene, namely1-[2-methyl-5-(p-N,N-dimethylaminophenyl)-3-thienyl]-2-[2-methyl-5-(3-methoxylphenyl)-3-thienyl]
perfluorocyclopentene (1a), was synthesized. The compound showed good photochromism, high sensitivity and remarkable fatigue-resistance
both in solution and in poly(methyl methacrylate) (PMMA) matrix with UV/Vis light irradiation. The absorption maximum of its
closed-ring isomer was observed at 624 nm in PMMA amorphous film. It is a nice match for the wavelength of the recording laser
(633 nm). Using this target compound as recording medium, four types of polarization holographic optical recordings were performed
successfully using a He-Ne laser. The results showed that only the orthogonal circular polarization recording could obtain
a hologram with high diffraction efficiency and high signal-to noise-ratio. With multiplexing recording technology, three
types of polarization multiplexing holographic optical recordings, including angular multiplexing, polarization multiplexing,
and angular plus polarization multiplexing holographic recording, were also carried out perfectly based on its photoinduced
anisotropic phenomenon accompanying the photochromic reaction by photoirradiation. The results demonstrate that the multiplexing
recording technology is an effective method to improve recording capacity when using diarylethene 1 as recording medium. 相似文献
992.
A high molecular weight aromatic homopoly(ester‐imide) (homoPEI) was synthesized from homopoly(ester‐amic acids) (homoPEAA), which was obtained from the reaction of bis(trimellitic acid anhydride) phenyl ester (BTAH) with 4‐4'‐oxydianiline ether (ODA). This homoPEI was melt‐processable semi‐crystalline polymer and displayed dual endothermic transitions which were attributed to the different levels of crystal perfection and size in the crystal structures. Four high molecular weight aromatic copoly(ester‐imide)s (coPEIs) were synthesized via copoly(ester‐amic acids)s (coPEAA) from the reaction of 4, 4'‐oxydiphthalic anhydride (ODPA) and BTAH with ODA. The molar percentage of BTAH varied from 10 to 40%. When the molar percentages of BTAH were 30 and 40%, the resulting two coPEIs were crystallinable and their melting temperatures were 361°C and 356/371°C, respectively. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) results indicated that the crystal structures included short segments of BTAH/ODA and ODPA/ODA. The initial crystallization of the two coPEIs took place during imidization process. Thermogravimetric (TA) and mechanical analysis confirmed that both homoPEI and coPEIs showed almost no weight loss until 400°C in N2 and good mechanical properties. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
A colorimetric strategy based on conjugated polyelectrolyte aggregates has been applied to determine and distinguish anionic, cationic and non-ionic surfactants. 相似文献
994.
This paper reports the synthesis of a perylene-bridged bis(crown ether) through the condensation reaction between primary amine-armed dibenzo-24-crown-8 and 3,4,9,10-perylenetetracarboxylic dianhydride. Pseudorotaxane with a perylene moiety at the wheel and a fullerene unit in the middle of the axle was prepared, which was evidenced by 1H NMR and fluorescence experiments. Subsequent investigations show that the formation and disassociation of the pseudorotaxane can be controlled by the alternating addition of KPF6 and 18-crown-6, following the change of the florescence intensity of perylene.
相似文献995.
The syntheses and reactivity of the two N‐heterocyclic carbene (NHC)→ silylene complexes 2 and 4 have been investigated. The latter are easily accessible by reaction of the zwitterionic, N‐heterocyclic silylene LSi: 1 [L=Ar‐N‐C(=CH2)CH?C(Me)‐N‐Ar, Ar=2,6‐iPr2C6H3] with 1,3,4,5‐tetramethylimidazol‐2‐ylidene and 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene, respectively. While compound 2 undergoes facile rearrangement above ?20 °C to give the unsymmetrical N‐heterocyclic silylcarbene 3 , the derivative 4 remains unchanged even after boiling in benzene. The remarkable reactivity of 3 and 4 towards cyclohexylisocyanide has been examined which leads in a unique series of C? H, Si? H, and C? N bond activations to the new triaminosilanes 5 and 6 , respectively. The novel compounds 3 , 4 , 5 , and 6 were fully characterized by 1H, 13C, and 29Si NMR spectroscopy, EI‐MS, elemental analysis, and single‐crystal X‐ray diffraction. 相似文献
996.
Polyurea-entrapped palladium nanoclusters have been prepared by interfacial polymerization in W/O emulsion and showed high thermal stability and chemical stability with the content of 0.12 mmol g?1 Pd. This catalyst exhibited dual catalytic activity for reduction of nitro compounds and hydrodehalogenation of aromatic chlorides in atmospheric hydrogen with 100% yield for reduction of nitro compounds and >99% yield for hydrodehalogenation of aromatic chlorides. This immobilizing method was particularly effective and eliminated the need of special chelating groups. 相似文献
997.
998.
Minghuo Wu Yingzhuang Chen Ren’an Wu Ruibing Li Hanfa Zou Bo Chen Shouzhuo Yao 《Journal of chromatography. A》2010,1217(26):4389-4394
A chloropropyl-functionalized silica (CP-silica) hybrid monolithic column was synthesized within the confines of a capillary via the sol–gel process using tetramethoxysilane (TMOS) and (3-chloropropyl)-trimethoxysilane (CPTMS) as the precursors. The resulting CP-silica hybrid monolith inside the capillary showed homogeneous macroporous morphology and was well attached to the inner wall of the capillary. The obtained CP-silica hybrid monolithic capillary column demonstrated the inherent hydrophobic property and could be applied as a reversed-phase stationary phase in CEC directly. Due to the great chemical reactivity of the incorporated chloro groups on the hybrid silica monolithic matrix, the chloropropyl moieties on the surface of the hybrid silica monolith matrix could be conveniently further modified by a tertiary amine of N,N-dimethyl-N-dodecylamine (DMDA) via the nucleophilic substitution reaction at 70 °C to introduce a dodecyl groups (C12) onto the CP-silica hybrid monolithic matrix. The resulting C12-silica hybrid monolithic column not only demonstrated the significantly enhanced hydrophobic property in the separation of alkylbenzenes in reversed-phase capillary electrochromatography (RP-CEC), but also the strong electroosmotic flow (EOF) in a wide pH range. Five alkylbenzenes could be baseline separated in 3 min with column efficiency ranging from 189 700 to 221 000 N/m with a 70% ACN running buffer in CEC. 相似文献
999.
1000.
A novel composite material of multi-walled carbon nanotubes (MWNTs)-Sudan IV molecularly imprinted polymers (MIPs) was prepared by surface molecular imprinting technique in combination with sol-gel technology. The MWNTs-MIPs were evaluated by scanning electron micrograph (SEM), Fourier transform infrared spectroscopy (FT-IR), and adsorption experiments. The results showed that the MWNTs-MIPs exhibited good selective recognition to Sudan IV. The maximum saturated binding capacity (Qmax) is 63.2 μmol g−1. Applied as sorbent, the MWNTs-MIPs were used for the determination of trace Sudan IV in chilli powder by on-line solid-phase extraction-high-performance liquid chromatography (SPE-HPLC). The results showed that an enrichment factor of 741 was achieved with a loading flow rate of 1.0 mL min−1 for sampling 50 mL. The MWNTs-MIPs provided a fast and convenience determination platform for Sudan IV in real samples. 相似文献