 |
 |
 |
| 24小時(shí)熱門(mén)版塊排行榜 |
- >論壇更新日志 (4597)
- >導(dǎo)師招生 (785)
- >考研 (585)
- >文獻(xiàn)求助 (301)
- >蟲(chóng)友互識(shí) (205)
- >考博 (149)
- >休閑灌水 (148)
- >基金申請(qǐng) (122)
- >碩博家園 (94)
- >招聘信息布告欄 (86)
- >博后之家 (65)
- >綠色求助(高懸賞) (40)
- >論文投稿 (28)
- >找工作 (23)
- >SciFinder/Reaxys (20)
- >外文書(shū)籍求助 (13)
 |
 |
 |
||
 |
 |
 |
 |
 |
| 4 | 1/1 | 返回列表 |
| 查看: 464 | 回復(fù): 3 | |||
shinyman金蟲(chóng) (正式寫(xiě)手)
|
[交流]
那位大蝦幫忙翻下摘要
|
||
|
小弟我剛大三 專(zhuān)業(yè)文獻(xiàn)還沒(méi)看幾篇，我們老師就讓我們翻摘要，好多詞不認(rèn)識(shí)啊 金山也查不到，急人，麻煩哪位大蝦幫忙，先謝謝了 Density functional theory calculations of the local spin densities of 3-substituted thiophenes and the oligomerization mechanism of 3-methylsulfanyl thiophene Abstract For obtaining a theoretical basis for the one-step formation of regioregular a-conjugated oligo- and polythiophenes, the electronic states of 3-substituted thiophenes and oligo(3-methylsulfanylthiophene)s were elucidated by molecular orbital calculations using density functional theory (DFT) with the Becke-type three parameters functionals (B3LYP) and the 6-31G(d) basis set. The reactivity for coupling reaction of mono- and oligo-thiophenes are inferred from the calculated unpaired electron spin densities of the respective radical cations, and the ionization potentials which correspond to the energies for generating radical cations during oxidative processes were estimated. The major regioselective products of the ligomerization of 3-(methylsulfanyl)thiophene [J. Org. Chem. 61 (1996) 8285] can be well understood in terms of the magnitude of spin densities. Since the steric hindrance between the methylsulfanyl side chains does not interfere with the coupling reaction occurring between 2-positions (C-2) of thiophene rings, the initiating reaction of 3-(methylsulfanyl)thiophene is the generation of a head-to-head (HH) dimer. On the other hand, the head-to-tail (HT) dimer would play an important role in the propagation reactions of 3-(4-butylphenyl)thiophene. This originates from the highest spin density at the 50-position of the HT dimer and the low probability of the HH coupling due to the steric hindrance between thiophene ring and phenyl group. Formation of Regioregular Head-to-Tail Poly[3-(4-butylphenyl)thiophene] by an Oxidative Coupling Polymerization with Vanadium Acetylacetonate ABSTRACT: The mechanism for the formation of head-to-tail (H–T) poly[3-(4-butylphenyl)thiophene] by oxidative coupling polymerization with a catalytic amount of vanadium acetylacetonate was investigated. Polymerization was carried out in the presence of vanadium acetylacetonate, trifluoromethane sulfonic acid, and trifluoroacetic anhydride under an oxygen atmosphere in 1,2-dichloroethane at room temperature. Polymers and oligomers obtained after several polymerization times were characterized by gel permeation chromatography, IR, and NMR spectroscopies. With these findings and the reactivity of monomer and dimers based on ab initio density functional theory, the polymerization was found to proceed mainly through the formation of H–T linkages due to the high spin density at the 2-position of 3-(4-butylphenyl)thiophene and the calculated total energy of dimers. 我剛來(lái) 窮的很 只發(fā)10個(gè)BB吧 |
回復(fù)此樓» 猜你喜歡
0854電子信息求調(diào)劑 324
已經(jīng)有3人回復(fù)
-
303求調(diào)劑
已經(jīng)有3人回復(fù)
-
336求調(diào)劑
已經(jīng)有3人回復(fù)
-
306求調(diào)劑
已經(jīng)有9人回復(fù)
-
工科0856求調(diào)劑
已經(jīng)有4人回復(fù)
-
工科材料085601 279求調(diào)劑
已經(jīng)有10人回復(fù)
-
081700 調(diào)劑 267分
已經(jīng)有4人回復(fù)
-
276求調(diào)劑。有半年電池和半年高分子實(shí)習(xí)經(jīng)歷
已經(jīng)有9人回復(fù)
-
263求調(diào)劑
已經(jīng)有9人回復(fù)
-
求老師收我
已經(jīng)有3人回復(fù)
4樓2007-12-24 22:14:10
shinyman
金蟲(chóng) (正式寫(xiě)手)
- 應(yīng)助: 0 (幼兒園)
- 金幣: 1220.9
- 散金: 39
- 帖子: 354
- 在線(xiàn): 225.2小時(shí)
- 蟲(chóng)號(hào): 446651
- 注冊(cè): 2007-10-29
- 性別: GG
- 專(zhuān)業(yè): 高分子合成化學(xué)
2樓2007-12-23 12:02:14
darliu
榮譽(yù)版主 (職業(yè)作家)
- 應(yīng)助: 0 (幼兒園)
- 貴賓: 2.92
- 金幣: 22714.4
- 紅花: 14
- 帖子: 4022
- 在線(xiàn): 12.5小時(shí)
- 蟲(chóng)號(hào): 293348
- 注冊(cè): 2006-11-04
- 性別: GG
- 專(zhuān)業(yè): 化工系統(tǒng)工程
- 管轄: 石油化工
3樓2007-12-23 12:37:03
相關(guān)版塊跳轉(zhuǎn)
我要訂閱樓主 shinyman 的主題更新
| 4 | 1/1 | 返回列表 |
| 最具人氣熱帖推薦 [查看全部] | 作者 | 回/看 | 最后發(fā)表 | |
|---|---|---|---|---|
5