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排序方式: 共有68条查询结果,搜索用时 46 毫秒
1.
In a 2:2 reaction with silver(I) chloride or bromide, 1,5-bis(1-phospholano)pentane ( 1a ) afforded frame-like macrocyclic structures, with intra- ( 2 , Cl) or intermolecular ( 3 , Br) halido bridges. In contrast, 1,7-bis(1-phospholano)heptane ( 1b ) formed coordination polymers 4a (Cl) and 4b (Br) with bridging bis-phospholane and halido ligands. A unique paddle wheel-type metallacryptand structure 5 was obtained from 1a and silver(I) bromide in a 2:3 reaction (M:L). All complexes were fully characterized by NMR, IR spectroscopy, mass spectrometry, and X-ray crystallography. 相似文献
2.
以三羟甲基丙烷三丙烯酸酯(TMPTA)-苯乙烯(St)为单体,偶氮二异丁腈(AIBN)为自由基引发剂,通过在乙醇中的沉淀聚合可制得高交联单分散P(TMPTA-St)聚合物微球.对单体转化率,微球以及可溶性低聚物的产率进行了测试.结果表明,使用10 wt%至60 wt%的交联剂TMPTA进行聚合可获得单分散微球,产率在50%左右.增加TMPTA用量可提高微球产率和单体转化率.增加引发剂AIBN用量对提高微球产率也有促进作用,但同时可溶性低聚物产率也增加.向乙醇中加入水作为反应介质结合适当增加AIBN用量可使单体转化率达到98%,微球产率高于90%.对实验结果进行了解释,对聚合机理进行了讨论. 相似文献
3.
Angelina Hormaza 《Tetrahedron》2004,60(1):229-233
Chalcones can serve as C2 or C3 components for the formation of 1H-pyrroles. In particular the reaction with tosylisocyanid could be applied to the oligochalcones 2d-g with up to 6 enone units. A series of cross-conjugated oligomers 8d-g was obtained; these compounds consist of a chain of 1,4-phenylene, carbonyl and 1H-pyrrole-3,4-diyl building blocks. The benzene rings bear two propoxy sidechains in order to enhance the solubility. 相似文献
4.
5.
《中国化学快报》2020,31(5):1248-1250
(±)-Magoilgomer A [(±)-1] and magoilgomer B (2) were identified from the bark of Magnolia officinalis var. biloba. (+)-1 and (−)-1 were a pair of novel biphenyl derivatives featuring three C6-C3 subunits. 2 was an unprecedented adduct containing magnolol and honokiol. These three oligomers possessed new parallel mode which should be biosynthesized from the coupling of three or four C6-C3 subunits. The structures of (±)-1 and 2 were elucidated based on the spectroscopic data analyses and electronic circular dichroism (ECD) calculations. 2 exhibited neuroprotective effects of oxygen glucose deprivation-induced SK-N-SH cell injury. 相似文献
6.
Novel blue emitters, oligo-MCPPs (tri-MCPP, tetra-MCPP, and penta-MCPP), have been synthesized and characterized. The introduction of cyclopenta[def]phenanthrene (CPP) units into the structure of oligo-MCPPs gave LEDs with high efficiency and pure blue emission. UV-visible absorption spectra of the thin films of these compounds appear at 333-354 nm, and their maximum PL emission at 416-447 nm. Multilayer organic EL devices with oligo-MCPPs as an emitting layer showed the turn-on voltage of about 4.8 V, the maximum brightness of 1076 cd/m2 (at 8.2 V), the maximum luminescence efficiency of 0.81 cd/A, and the CIE coordinates of (0.17, 0.14) with blue color. 相似文献
7.
Dr. John H. Viles 《Angewandte Chemie (International ed. in English)》2023,62(25):e202215785
The accumulation of the amyloid-β peptides (Aβ) is central to the development of Alzheimer's disease. The mechanism by which Aβ triggers a cascade of events that leads to dementia is a topic of intense investigation. Aβ self-associates into a series of complex assemblies with different structural and biophysical properties. It is the interaction of these oligomeric, protofibril and fibrillar assemblies with lipid membranes, or with membrane receptors, that results in membrane permeability and loss of cellular homeostasis, a key event in Alzheimer's disease pathology. Aβ can have an array of impacts on lipid membranes, reports have included: a carpeting effect; a detergent effect; and Aβ ion-channel pore formation. Recent advances imaging these interactions are providing a clearer picture of Aβ induced membrane disruption. Understanding the relationship between different Aβ structures and membrane permeability will inform therapeutics targeting Aβ cytotoxicity. 相似文献
8.
Ruta Lazauskaite Egle Stanislovaityte Juozas V. Grazulevicius 《Monatshefte für Chemie / Chemical Monthly》2008,139(8):887-893
An absorbance probe method was used for the investigation of photolysis of cationic photoinitiators. The rates of the photolysis
of diphenyliodonium hexafluorophosphate (DPIH), diphenyliodonium tetrafluoroborate (DPIB), di(tert-butylphenyl)iodonium tetrafluoroborate (DTIB), di(tert-butylphenyl)iodonium bromate (DTIBr), triphenylsulfonium hexafluorophosphate (TPS) and cyclopropyldiphenylsulfonium tetrafluoroborate (CPS) were studied in the presence of acid indicator quinaldine red (QR) in acetonitrile. Diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate showed the highest photolysis
rate. Photopolymerization of 1,3-di(9-carbazolyl)-2-propanol glycidyl ether (DCPGE) initiated with the iodonium and sulfonium salts in bulk and in solution was studied. It was established that the highest
initial rate of polymerization is characteristic of DCPGE photopolymerization initiated with DPIH and TPS in bulk. The oligomers of DCPGE of number average molecular weight (
) ranging from 710 to 1220 were obtained in these reactions in bulk and those with
ranging from 1300 to 1600 were obtained in solution.
Correspondence: Ruta Lazauskaite, Juozas V. Grazulevicius, Department of Organic Technology, Kaunas University of Technology,
Radvilenu plentas 19, LT-50254 Kaunas, Lithuania. 相似文献
9.
Rainer E. Martin Franois Diederich 《Angewandte Chemie (International ed. in English)》1999,38(10):1350-1377
The development of structure–property relationships for monodisperse oligomers has been extremely useful to rationalize the properties of high molecular weight linear π-conjugated polymers. A great variety of spectacular molecular architecture has been generated, culminating in the recent preparation of molecular wires such as 1 with lengths exceeding 10 nm that have potential applications in molecular electronics. 相似文献
10.
Ruta Lazauskaite Maryte Daskeviciene Vytautas Getautis Juozas V. Grazulevicius 《Monatshefte für Chemie / Chemical Monthly》2009,140(5):565-571
Abstract Photoinitiated cationic polymerizations of various epoxy monomers bearing a carbazole moiety, 9-[3-(allyloxy)-2-(oxiran-2-ylmethoxy)propyl]-9H-carbazole, 9-[3-methoxy-2-(oxiran-2-ylmethoxy)propyl]-9H-carbazole, 9-[2-(oxiran-2-ylmethoxy)ethyl]-9H-carbazole, as well as a composition of 3,6-dibromo-9-(oxiran-2-ylmethyl)-9H-carbazole with 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate were investigated in bulk using triphenyl carbenium
salts having anions such as BF4
−, SnCl5
−, and SbCl6
−. Dark polymerizations of the carbazolyl monomers in the presence of the initiators are studied. These photoinduced polymerization
reactions give oligomers of degree of polymerization 4-22. The effect of the anion of the photoinitiator and polymerization
time on the polymerization reaction is discussed.
Graphical abstract
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