直接证据表明,在金属稳定中间体中表现出的铜 (II/I) 电子转移动力学上,具有几何约束的"静态状态"效应
1Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
Journal of the American Chemical Society
|June 14, 2001
概括
铜复合体中的性状态效应首次得到了定量证明. 测量了各种铜复合体的电子转移速率,揭示了对受约束几何形状及其对反应性的影响的见解.
科学领域:
- 无机化学 无机化学 有机化学
- 生物有机化学 生物有机化学
- 物理化学 物理化学
背景情况:
- 对电子转移的"静态"状态或受约束几何效应缺乏定量验证.
- 铜 (II/I) 复合物在生物系统和催化中至关重要,使得它们的电子转移动力学具有重大意义.
研究的目的:
- 量化证明铜 (II/I) 系统中实态状态效应的大小.
- 为了研究密切相关的铜复合体的电子转移动力学,具有不同程度的几何约束.
主要方法:
- 合成和X射线衍射分析5个Cu (II) 和1个Cu (I) 复合体,其中14S (S4) 的二聚体被修饰为环素.
- 测定与六种氧化剂/减少剂在水溶液中的交叉反应速率常数.
- 使用马库斯交叉关系计算电子自我交换速率常数 (k(11)
- 用快速扫描循环电压测量的稳定常数评估元稳定中间体的速率常数.
主要成果:
- 评估了16个电子自我交换速率常数,用于8个相关的Cu (II/I) 系统,覆盖了近6个数量级.
- 确定了研究的Cu (II/I) 系统的双路径方形方案机制.
- 计算的特异性自我交换率常数对应变中介物种,其中大多数属于10(5)-10(6) M(-1) s(-1) 范围.
结论:
- 提供了第一个明确的定量证明,在Cu (II/I) 系统中实态状态概念的有效性.
- 约束的几何结构显著影响电子传输速率,与蓝铜蛋白质的电子传输速率相当.
- 这项研究为了解金属酶和合成催化剂中的电子转移提供了新的框架.
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