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排序方式: 共有118条查询结果,搜索用时 15 毫秒
71.
We demonstrate the patterning of silica substrates with thymine (Thy-PS) and positively charged N-methylpyridinium (PVMP) polymers using photolithography and the subsequent orthogonal modification of these surfaces using diaminopyridine-functionalized polystyrene (DAP-PS) and carboxylate-derivatized CdSe/ZnS core-shell nanoparticles (COO-NP) through diamidopyridine-thymine three-point hydrogen bonding and pyridinium-carboxylate electrostatic interactions, respectively. This two-component orthogonal surface modification was accomplished in a self-sorting, single-step fashion, providing a versatile tool for the rapid and efficient creation of complex materials. 相似文献
72.
Abstract
A simple, mild, and highly efficient method has been developed for the preparation of functionalized tetrahydropyridines and β-amino carbonyls from the multicomponent reactions involving in situ imines and vanadium (III) chloride as a Lewis acid. The multicomponent reaction of two equivalents of aromatic aldehyde, two equivalents of amine, and one equivalent β-keto ester in the presence of catalytic amount of VCl3 provides highly atom economic five-component tetrahydropyridines in very good yields. The same catalyst was found useful for the efficient synthesis of a wide variety of β-amino ketones using direct-type Mannich reaction of aromatic aldehyde, amine, and aromatic ketones. The notable advantages of this method are simple procedure, short reaction time and good yields, and applicable to broad range of substrates. 相似文献73.
74.
75.
The present study investigates the effects of Lewis acid and protonic acid on the chemical polymerization of indole using
electrical conductivity measurements and nuclear magnetic resonance, UV–visible, and Fourier transform infrared spectroscopy
techniques. These effects are explained by theoretical calculations on the basis of molecular mechanic (MM+) and semi-empirical
Austin Model 1 methods. As a result, it has been shown that indole interacts with proton and Lewis acids by the way of different
mechanisms. Theoretical research has demonstrated that while BF3, a Lewis acid, adds to the N atom in the indole, which has a basic character due to its lone-pair electrons, proton, H+ adds to the indole ring on C3 atom. These additions affect both the polymerization of indole and the conductivity of polyindole. Polyindole conductivity
is increased by BF3 addition and decreased by H+ addition. 相似文献
76.
Photochemically prepared polysulfone/poly(ethylene glycol) amphiphilic networks and their biomolecule adsorption properties 总被引:1,自引:0,他引:1
Dizman C Demirkol DO Ates S Torun L Sakarya S Timur S Yagci Y 《Colloids and surfaces. B, Biointerfaces》2011,88(1):265-270
Polysulfone/poly(ethylene glycol) amphiphilic networks were prepared via in situ photo-induced free radical crosslinking polymerization. First, the hydrophobic polysulfone diacrylate (PSU-DA) oligomer was synthesized by condensation polymerization and subsequent esterification processes. Then, the obtained oligomer was co-crosslinked with the hydrophilic poly(ethylene glycol) diacrylate (PEG-DA) or poly(ethylene glycol) methyl ether acrylate (PEG-MA) at different feed ratios. In the case of PEG-MA, the resulting network possessed dangling pendant hydrophilic chains on the crosslinked surface. The structure and the morphology of the membranes were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). The enhancement of surface hydrophilicity was investigated by water contact angle measurements. The biomolecule adsorption properties of these networks were also studied. The biomolecules easily adsorbed on the surface of the hydrophobic polysulfone networks whereas dangling hydrophilic chains on the surface prevented the adsorption of the biomolecules. 相似文献
77.
Karadag M Yilmaz G Toiserkani H Demirkol DO Sakarya S Torun L Timur S Yagci Y 《Macromolecular bioscience》2011,11(9):1235-1243
The use of PSU‐Py prepared by click chemistry as a platform in membrane‐bottom microwell plates for oxidase and hydrolase/oxidase‐based enzyme assays is studied. For the GOx assay, the postulated fluorescence mechanism is based on the consumption of glucose by dissolved oxygen and GOx in the microwell plates covered with the PSU‐Py membrane. For the AG‐GOx assay, maltose is used as AG substrate and hydrolyzed to glucose which is then oxidized by the GOx activity. It is shown that the PSU‐Py membrane acts as a fluorescence indicator of the enzymatic reactions, and both GOx and AG/GOx enzyme assays are successfully applied for glucose, maltose and acorbose analysis in the range 0.125–2.0 × 10?3 M glucose, 0.05–0.5 × 10?3 M maltose, and 0.0125–0.1 mg · mL?1 acorbose, respectively.
78.
This present study describes a pencil graphite electrode surface covered with Cu(II) and Fe(III) complexes based on Salophen derivative Schiff bases in acetonitrile solution containing LiClO4 as a supporting electrolyte. Cyclic voltammetry method was used for the surface modification procedure with 25 cycle at a sweep rate of 50 mV s?1. Some characterization methods were used to identify of the prepared modified surfaces including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Ultraviolet‐visible Spectroscopy (UV‐Vis), and Scanning Electron Microscopy/Energy Dispersive X‐ray Spectroscopy (SEM/SEM‐EDX). The catalytic activity of these modified surfaces on the electrochemical oxidation of catechol (CC) was investigated and they compared with each other. The results demonstrated that these modified electrodes showed perfect electrocatalytic activity on the catechol determination, however the modified electrode prepared with the Cu(II) complex has higher catalytic activity than this prepared with the Fe(III) complex thanks to its the lower detection limit. 相似文献
79.
Abu T. Khan Tasneem Parvin Lokman H. Choudhury Subrata Ghosh 《Tetrahedron letters》2007,48(13):2271-2274
A wide variety of alkyl- and cycloalkyl-arenes undergo benzylic C-H oxidation by employing a combination of 48% hydrogen bromide and 30% hydrogen peroxide in dichloromethane at room temperature. In addition, a chemoselective oxidation at the benzylic position is feasible by deactivating the aromatic ring using the same combination. 相似文献
80.