III-氧复合物的基本性 控制质子合电子转移反应的热力学
Priya Singh1, Markell J A Lomax1, Adedamola A Opalade1
1Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States.
Inorganic chemistry
|November 5, 2024
概括
结合显著影响依赖的酶. 这项研究表明,虽然键增强了基本性并改变了键解离能,但它意外地减缓了合成复合物的协同质电子转移 (CPET) 反应.
科学领域:
- 生物有机化学 生物有机化学
- 酶的机制 酶的机制
- 催化剂是一种催化剂.
背景情况:
- 在生物系统中,依赖的酶至关重要.
- 这些酶往往使用Mn(III) - 氧单元进行协同的质子 - 电子转移 (CPET) 反应.
- 之前的研究表明,与氧联体的结可以加速CPET.
研究的目的:
- 为了研究结对合成复合物中氧联体的基本性的影响.
- 评估这些基本性变化如何影响CPET反应率.
- 了解介导催化中结合的机械含义.
主要方法:
- 合成复合物的合成 [MnIII(OH) ((PaPy2Q) ]+和 [MnIII(OH) ((PaPy2N) ]+.
- 对相应的Mn(III) - 水复合物的pKa值的确定.
- 减少潜力的测量和O-H键解离自由能量 (BDFEs) 的计算.
主要成果:
- 在[MnIII(OH) ((PaPy2N) ]+ (13.1) 中的联体的pKa明显高于在[MnIII(OH) ((PaPy2Q) ]+ (7.6),表明由于结合而增加的基本性.
- 对于Mn (II) - 水复合物的BDFEs计算为77 kcalmol-1和85 kcalmol-1.
- 与热力学预期相反,在BDFE较高的复合体中观察到较慢的CPET率,这表明CPET机制更异步.
结论:
- 与Mn(III) - 氧联体的结会增加其基本性.
- 热力学驱动力和CPET速率之间的关系是复杂的,可以由CPET同步度的影响.
- 与热力学趋势的偏差表明,在某些条件下,反应机制可能发生变化,可能涉及质子转移.
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