- Grafting and coloring onto silver nanoparticles by photoinduced surface modification
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(Figure Presented) Surface modification of metal nanostructures can create multifunctional materials potentially very useful in many application fields and, consequently, has been the subject of intensive studies. This work reported the modification of silver nanoparticles (Ag NPs) by UV-induced interface reactions, a method controllable in both the color and the surface chemistry of the nanoparticles. Using poly(N-vinyl-2-pyrrolidone) (PVP) as the protecting polymer, Ag NPs were synthesized in ethanol and then mixed with F-bromoisobutyric acid (BIBA). When the mixture is exposed to UV irradiation, Ag NPs present themselves in a serial tone from pale blue to blue, dark blue, and finally purple with the progress of the interface reactions. It is shown that these color changes are directly related to the chemical components on the surface of Ag NPs, and hence the correlation of the colors with the chemical states of main components on the surface of Ag NPs has been made during the course of interface reactions.
- Zhang, Hucheng,Zhang, Liwei,Wang, Jianji
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Read Online
- Method for synthesizing ethyl alpha-bromoisobutyrate
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The invention discloses a method for synthesizing ethyl alpha-bromoisobutyrate. The ethyl alpha-bromoisobutyrate is synthesized by using isobutyric acid as a starting material through bromination andesterification. N-bromosuccinimide or N-bromophthalimide is used as a bromination reagent in the bromination, so as to improve the utilization of bromine atoms and improve the safety of the process; the esterification is catalyzed by a double catalytic system, and the zinc powder added and the trace bromine of the bromination form ZnBr2 as a catalyst for the esterification, so the scheme has fewerside reactions, low corrosion, high selectivity and good product appearance quality.
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Paragraph 0043; 0047-0049; 0050; 0054-0057; 0061-0063
(2019/01/08)
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- Structure-LCST relationships for end-functionalized water-soluble polymers: An "accelerated" approach to phase behaviour studies
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A novel "high throughput" technique for LCST measurement was developed which is able to identify the effect of subtle changes in end group composition on the aqueous phase behaviour of water-soluble poly(2- (dimethylamino)ethyl methacrylate). The Royal Society of Chemistry.
- Jana, Satyasankar,Rannard, Steven P.,Cooper, Andrew I.
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p. 2962 - 2964
(2008/02/11)
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- Spin adducts of several N-2-(2-alkoxycarbonyl-propyl)-α- pyridylnitrone derivatives with superoxide, alkyl and lipid-derived radicals
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Several derivatives of N-t-butyl-α-phenylnitrone (PBN) such as N-2-(2-ethoxycarbonyl-propyl)-α-phenylnitrone (EPPN) have recently been reported to form superoxide spin adducts (t1/2 ca. 2-7 min at pH 7.0), which are considerably more stable than their respective PBN or DMPO adducts (t1/2 ca. 10 and 45 s, respectively). In continuation of our studies on structure optimization of EPPN derivatives, a series of 12 novel spin traps with 2-, 3- and 4-pyridinyl substituents was synthesized and fully characterized by 1H NMR, 13C NMR and IR spectroscopy. In addition to the replacement of the phenyl ring by a 2-, 3- or 4-pyridinyl substituent, the ethoxy group of the parent compound EPPN was replaced by either a propoxy, iso-propoxy, or cyclopropylmethoxy moiety. Superoxide adducts of all PPyN derivatives were considerably more stable than those of the respective EPPN derivatives with half-lives ranging from about 6 to 11 min. In addition, alkoxyl radical adducts were also considerably more stable than those of the EPPN series. Hydroxyl radical adducts were not detected, on the other hand, very stable spin adducts were formed from a series of carbon centered radicals, e.g. from the methyl or hydroxymethyl radical. The novel spin traps are offering an alternative to PBN or POBN, especially where the higher stability of oxygen-centered radical adducts is of major importance. All of them can easily be synthesized from commercially available compounds in two or three steps.
- Stolze, Klaus,Udilova, Natascha,Rosenau, Thomas,Hofinger, Andreas,Nohl, Hans
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p. 185 - 193
(2007/10/03)
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- Spin trapping of superoxide, alkyl- and lipid-derived radicals with derivatives of the spin trap EPPN
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The N-t-butyl-α-phenylnitrone derivative N-2-(2-ethoxycarbonyl-propyl)-α-phenylnitrone (EPPN) has recently been reported to form a superoxide spin adduct (t1/2=5.25min at pH 7.0), which is considerably more stable than the respective N-t-butyl-α -phenylnitrone or 5,5-dimethylpyrroline N-oxide adducts (t1/2 ～10 and 45s, respectively). In continuation of our previous studies on structure optimization of 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide derivatives, a series of six different EPPN derivatives was synthesized and characterized by 1H NMR, 13C NMR and IR spectroscopy. The ethoxy group of EPPN was replaced by a propoxy, iso-propoxy, n-butoxy, sec-butoxy, and tert-butoxy moiety, as well as the phenyl by a pyridyl ring. Electron spin resonance spectra and stabilities of the superoxide adducts of the propoxy derivatives were found to be similar to those of the respective EPPN adduct, whereas the electron spin resonance spectra of the superoxide adducts of N-2-(2-ethoxycarbonyl-propyl)-α-(4-pyridyl) nitrone and the butoxy derivatives were accompanied by decomposition products. In contrast to the 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide series, no significant improvement of the superoxide adduct stability could be obtained when the ethoxy group was replaced by other substituents. Carbon centered radical adducts derived from methanol, ethanol, formic acid and linoleic acid hydroperoxide were more stable than those of 5,5-dimethylpyrroline N-oxide, whereas among the alkoxyl radicals only the methoxyl radical adduct could be detected.
- Stolze, Klaus,Udilova, Natascha,Rosenau, Thomas,Hofinger, Andreas,Nohl, Hans
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p. 1717 - 1726
(2007/10/03)
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- α-Oxo Sulfones. 4. Correction of a Pretended α-Oxo Sulfone by an Unambiguous Synthesis of the Revised Structure
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By an independent synthesis the oxidation product of 1,1-dichloro-2,2-dimethyl-1-(phenylthio)-3-butene (1) was shown not to be α-oxo sulfone "2" as published earlier but a phenylsulfonyl γ-butyrolactone, 3.This synthesis involves the intramolecular reaction of a sulfenic carboxylic mixed anhydride with an olefinic bond.A rationale for the formation of 3 from 1 is presented.
- Schank, K.,Frisch, A.,Zwanenburg, B.
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p. 4580 - 4582
(2007/10/02)
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