Probing the Mechanism for 2,4′-Dihydroxyacetophenone Dioxygenase Using Biomimetic Iron Complexes
Probing the Mechanism for 2,4′-Dihydroxyacetophenone Dioxygenase Using Biomimetic Iron Complexes
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利用仿生铁配合物探讨 2,4â²-二羟基苯乙酮双加氧酶的机制
DOI：
10.1021/acs.inorgchem.1c00167
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发表时间：
2021
影响因子：
4.6
通讯作者：
Chavez, Ferman A.
中科院分区：
文献类型：
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作者：
Banerjee, Atanu;Li, Jia;Molenda, Monika A.;Opalade, Adedamola A.;Adhikary, Amitava;Brennessel, William W.;Malkhasian, Aramice Y.;Jackson, Timothy A.;Chavez, Ferman A.
在这项研究中，我们报告了[Fe（T1 Et 4 iPrIP）（2-OH-AP）（OTf）]（OTf）（2）、[Fe（T1 Et 4 iPrIP）（2-O-AP）]（OTf）（3）和[Fe（T1 Et 4 iPrIP）（DMF）3]（OTf）3（4）（T1 Et 4 iPrIP =三（1-乙基-4-异丙基-咪唑基）膦; 2-OH-AP = 2-羟基苯乙酮; 2-O-AP-=单去质子化的2-羟基苯乙酮）的合成和表征。2和3作为非血红素酶2，4 ′-二氢苯乙酮（DHAP）双加氧酶或DAD的酶-底物加合物的模型络合物，而4作为DAD的铁形式的模型。通过X射线晶体学表征了配合物2 - 4，其显示T1 Et 4 iPrIP以三齿方式结合铁。配合物2还含有一个2-O-AP配体和一个三氟甲磺酸单齿配体，形成畸变八面体构型;配合物3含有一个2-O-AP配体，形成畸变三角双锥构型（τ = 0.56）。配合物4具有畸变的八面体构型，配体中有3个DMF配体。2的紫外-可见光谱比3更接近DAD-底物光谱，因此，认为DAD的底物以质子化形式结合。TD-DFT研究表明，2和3的可见吸收带是由于MLCT带。配合物2和3能够在O2存在下以化学计量和催化方式氧化配位底物模拟物。在相同的催化条件下，配合物4不能将2-OH-AP转化为产物;然而，在2当量2-OH-AP存在下，它被厌氧还原为2。
In this study, we report the synthesis and characterization of [Fe(T1Et4iPrIP)(2-OH-AP)(OTf)](OTf) (2), [Fe(T1Et4iPrIP)(2-O-AP)](OTf) (3), and [Fe(T1Et4iPrIP)(DMF)3](OTf)3(4) (T1Et4iPrIP = tris(1-ethyl-4-isopropyl-imidazolyl)phosphine; 2-OH-AP = 2-hydroxyacetophenone, and 2-O-AP–= monodeprotonated 2-hydroxyacetophenone). Both2and3serve as model complexes for the enzyme–substrate adduct for the nonheme enzyme 2,4′-dihydroacetophenone (DHAP) dioxygenase or DAD, while4serves as a model for the ferric form of DAD. Complexes2–4have been characterized by X-ray crystallography which reveals T1Et4iPrIP to bind iron in a tridentate fashion. Complex2additionally contains a bidentate 2-OH-AP ligand and a monodentate triflate ligand yielding distorted octahedral geometry, while3possesses a bidentate 2-O-AP–ligand and exhibits distorted trigonal bipyramidal geometry (τ = 0.56). Complex4displays distorted octahedral geometry with 3 DMF ligands completing the ligand set. The UV–vis spectrum of2matches more closely to the DAD-substrate spectrum than3, and therefore, it is believed that the substrate for DAD is bound in the protonated form. TD-DFT studies indicate that visible absorption bands for2and3are due to MLCT bands. Complexes2and3are capable of oxidizing the coordinated substrate mimics in a stoichiometric and catalytic fashion in the presence of O2. Complex4does not convert 2-OH-AP to products under the same catalytic conditions; however, it becomes anaerobically reduced in the presence of 2 equiv 2-OH-AP to2.