...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Bulletin of the Chemical Society of Japan >Direct Comparison of Chiral Substituent Effects for Viologens in Stereoselective Photoinduced Electron-Transfer. Reactions with Zinc Myoglobin
【24h】

Direct Comparison of Chiral Substituent Effects for Viologens in Stereoselective Photoinduced Electron-Transfer. Reactions with Zinc Myoglobin

机译：立体选择性光诱导电子转移中紫精的手性取代作用的直接比较。与锌肌红蛋白的反应

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In order to understand the detailed mechanisms of stereoselective photoinduced electron-transfer (ЕТ) reactions of zinc substituted myoglobin (ZnMb) with optically active viologens by flash photolysis, we prepared new optically active agents, such as (R,R)- and (S,5)-1,1'-bis(3-hydroxy-2-methylpropyl)-4,4'-biрyridinediylium dichioride ([ВМV]Cl_2). The photo-excited triplet state of ZnMb, ~3(ZnМb)~*, was successfully quenched by(R,R)- and (S,S')-[ВM V]~(2+) ions to fo the radical pair of ZnMb cation (ZnMb~+) and (R,R)- and (S,S)-[ВМV]~+, followed by a thermal back ЕТ reaction to the ground state. The ratio of the rate сonstants (k_q) for ЕТ quenching at 25°C, k_q(R,R)/k_q(S,S) = 1.1, indicates that the (R,R)-[ВМУ]~(2+) preferentially quenches~3(ZnMb)~*. The selectivity of the rate constants (k_ь) for the back ЕТ from (R,R)and (S,S)-[ВMV]~+ to ZnMb~+ at 25 °C was k_b(R,R)/k_b(S,S) = 0.83. The highest stereoselectivity of 1.3 for [HMV]~+ was found at low temperature (10°C) in the thermal back ЕТ reaction, where i÷i÷Нiu(R-S) = 6.2 1.9kJmol~(-1) and i÷i÷Siu(R-S)= 19 ià 2J mol~(-1) K~(-1) were obtained. The structural differences between [ ВMV]~(2+) and the other viologens imply that the bulky aromatic substituent seems to be more important than the distance from the chiral center to the viologen moiety in order to enhance the ЕТ stereoselectivity.
机译：为了了解通过闪光光解作用的锌取代的肌红蛋白（ZnMb）与旋光性紫精的立体选择性光诱导电子转移（ЕТ）反应的详细机理，我们制备了新的旋光剂，如（R，R）-和（S ，5）-1,1'-双（3-羟基-2-甲基丙基）-4,4'-联吡啶二基二水碘化物（[ВМV] Cl_2）。 ZnMb〜3（ZnМb）〜*的光激发三重态被（R，R）-和（S，S'）-[ВMV]〜（2+）离子成功淬灭以形成自由基对ZnMb阳离子（ZnMb〜+）和（R，R）-和（S，S）-[ВМV]〜+，然后进行热背ТТ反应至基态。 25°C时ЕТ淬火的速率常数（k_q）之比，k_q（R，R）/ k_q（S，S）= 1.1，表明（R，R）-[ВМУ]〜（2+）优先淬灭〜3（ZnMb）〜*。在25°C下从（R，R）和（S，S）-[ВMV]〜+到ZnMb〜+的背面ЕТ速率常数（k_ь）的选择性为k_b（R，R）/ k_b（S ，S）＝ 0.83。在低温（10℃）热背反应中发现[HMV]〜+的最高立体选择性为1.3，其中i÷i÷Нiu（RS）= 6.2 1.9kJmol〜（-1）和i÷i得到Siu（RS）＝ 19×2J mol·（-1）K〜（-1）。 [？MV]〜（2+）与其他紫罗兰素之间的结构差异表明，为了增强ÅТ立体选择性，庞大的芳族取代基似乎比从手性中心到紫精基团的距离更重要。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号