Electronic Effect on Bimetallic Catalysts: Cleavage of Phosphodiester Mediated by Fe(III)-Zn(II) Purple Acid Phosphatase Mimics
Electronic Effect on Bimetallic Catalysts: Cleavage of Phosphodiester Mediated by Fe(III)-Zn(II) Purple Acid Phosphatase Mimics
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双金属催化剂上的电子效应：Fe(III)-Zn(II) 紫色酸性磷酸酶模拟物介导的磷酸二酯裂解
DOI：
10.1021/acs.inorgchem.0c01011
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发表时间：
2020
影响因子：
4.6
通讯作者：
Zhao Cunyuan
中科院分区：
文献类型：
--
作者：
Zhou Xiaoyu;Zhang Xue-Peng;Li Weikang;Phillips David Lee;Ke Zhuofeng;Zhao Cunyuan
双金属体系是磷酸二酯催化水解的重要策略。紫色酸性磷酸酶（PAPs）酶是该领域典型的双金属催化剂。 DNA 二核苷酸类似物 BNPP–(BNPP–= 双(对硝基苯基)磷酸酯) 被异双核 [FeIII(μ-OH)ZnIIL]2+ 复合物 (L = 2-[N-双(2-吡啶基甲基)-氨甲基]-4-甲基-6-[N′-(2-吡啶基甲基)(2-羟基苯甲基)氨甲基]水解裂解的机制细节苯酚）使用密度泛函理论计算进行了研究。对具有单桥羟基和双桥羟基的催化剂进行了比较。计算结果表明双氢氧桥配合物能够更好地与底物结合。对于 BNPP 水解，双氢氧桥反应物异构化为单氢氧桥络合物，然后由铁中心上的羟基引发攻击。此外，具有给电子基团（Me）的催化剂在水解反应中优先于吸电子基团（Br和NO2基团）。这是因为取代基影响高位占据分子轨道，调节铁的路易斯酸度和金属键合水的 pKa 值。这些因素影响羟基的亲核性，导致催化活性的变化。为了进一步检查取代基的影响，计算了几个不同取代基（-CF3、-OMe、-OH、-NH2 和 -N(Me)2）的占据轨道能量。研究发现HOMO或HOMO-1能量随着σp值的增加而降低。此外，发现[FeIII(μ-OH)ZnIIL]2+配合物的催化活性主要受到与铁和锌中心配位的酚盐配体(B)的影响。 [FeIII(μ-OH)ZnIIL]2+ 配合物催化的 BNPP 水解反应的这些基本方面应有助于提高对该机理的理解以及涉及异双核金属配合物的催化剂设计。
The bimetallic system is an important strategy for the catalytic hydrolysis of phosphodiester. The purple acid phosphatase (PAPs) enzyme is a typical bimetallic catalyst in this field. Mechanistic details for the hydrolysis cleavage of the DNA dinucleotide analogue BNPP–(BNPP–= bis(p-nitrophenyl) phosphate) by hetero-binuclear [FeIII(μ-OH)ZnIIL]2+complexes (L = 2-[N-bis(2-pyridylmethyl)-aminomethyl]-4-methyl-6-[N′-(2-pyridylmethyl)(2-hydroxybenzyl) aminomethyl] phenol) were investigated using density functional theory calculations. The catalysts with single-bridged hydroxyl and double-bridged hydroxyl groups were compared. The calculation results show that the doubly hydroxide-bridged complex could better bind to substrates. For the BNPP–hydrolysis, the doubly hydroxide-bridged reactant isomerizes into a single hydroxide-bridged complex, and then the attack is initiated by the hydroxyl group on the iron center. In addition, the catalyst with the electron-donating group (Me) was determined to take precedence over electron-withdrawing groups (Br and NO2groups) in the hydrolysis reaction. This is because the substituents affect the high-lying occupied molecular orbitals, tuning the Lewis acidity of iron and pKavalues of the metal-bonded water. These factors influence the hydroxyl nucleophilicity, leading to changes in catalytic activity. To further examine substituent effects, the occupied orbital energies were calculated with several different substituent groups (-CF3, -OMe, -OH, -NH2, and -N(Me)2). It was found that the HOMO or HOMO-1 energy decreases with the increase of the σpvalue. Further, the catalyst activity of the [FeIII(μ-OH)ZnIIL]2+complexes was found to be mainly affected by the phenolate ligand (B) coordinated to the iron and zinc centers. These fundamental aspects of the hydrolysis reactions of BNPP–catalyzed by [FeIII(μ-OH)ZnIIL]2+complexes should contribute to improved understanding of the mechanism and to catalyst design involving hetero-binuclear metals complexes.