Steric effects on the catalytic activities of zinc(ii) complexes containing [12]aneN3 ligating units in the cleavage of the RNA and DNA model phosphates
作者:Yang Song、Ju Zan、Hao Yan、Zhong-Lin Lu、Ruibing Wang
DOI:10.1039/c2ob25624j
日期:——
synergetic effects of up to 561 folds. pH jump experiments confirmed that the rate-limiting step in the cleavage of 3 by Zn2-8 involved the binding process, while that in the reaction with 4 was the chemical cleavage of the P–O bond. Steric effects in the cleavage reactions were analyzed in detail and were compared with the electronic effect caused by oxy anion bridging group in the di-[12]aneN3 ligand
合成并表征了一系列N-甲基化的单和二[12] aneN 3配体(5-9)。空间模型对RNA模型2-羟丙基4-硝基苯基磷酸酯(HPNPP,3)和DNA模型甲基4-硝基苯基磷酸酯(MPNPP,4)的裂解对其单核和双核锌(II)配合物催化活性的空间影响。在甲醇已在25°C下进行了研究。在由[12] aneN 3主链中的N-甲基化作用的单核络合物催化的磷酸盐3裂解过程中,k obs对[Zn(II)]的图随着曲率的增加而从上曲率变为线性。甲基化,表明N-甲基化导致负责协同作用的双核缔合的减少。相比于与复杂的活动非甲基二- [12] ANEN 3配体,这些的双核锌(II)配合物(锌2 - 8),其具有两个如通过两个模型化合物的裂解的二级速率常数和协同作用所测量的,N-甲基基团减少了两个数量级。为了通过充分催化反应Ñ甲基化的双核配合物(锌2 - 9),没有观察到协同效应。然而,复杂的Zn 2 - 8仍表