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Banerjee A, Li J, Molenda MA, Opalade AA, Adhikary A, Brennessel WW, Malkhasian AYS, Jackson TA, Chavez FA. Probing the Mechanism for 2,4'-Dihydroxyacetophenone Dioxygenase Using Biomimetic Iron Complexes. Inorg Chem 2021; 60:7168-7179. [PMID: 33900072 DOI: 10.1021/acs.inorgchem.1c00167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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). Both 2 and 3 serve as model complexes for the enzyme-substrate adduct for the nonheme enzyme 2,4'-dihydroacetophenone (DHAP) dioxygenase or DAD, while 4 serves as a model for the ferric form of DAD. Complexes 2-4 have been characterized by X-ray crystallography which reveals T1Et4iPrIP to bind iron in a tridentate fashion. Complex 2 additionally contains a bidentate 2-OH-AP ligand and a monodentate triflate ligand yielding distorted octahedral geometry, while 3 possesses a bidentate 2-O-AP- ligand and exhibits distorted trigonal bipyramidal geometry (τ = 0.56). Complex 4 displays distorted octahedral geometry with 3 DMF ligands completing the ligand set. The UV-vis spectrum of 2 matches more closely to the DAD-substrate spectrum than 3, and therefore, it is believed that the substrate for DAD is bound in the protonated form. TD-DFT studies indicate that visible absorption bands for 2 and 3 are due to MLCT bands. Complexes 2 and 3 are capable of oxidizing the coordinated substrate mimics in a stoichiometric and catalytic fashion in the presence of O2. Complex 4 does 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 to 2.
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Affiliation(s)
- Atanu Banerjee
- Dr. K. C. Patel R & D Centre, Charotar University of Science and Technology (CHARUSAT), P D Patel Institute of Applied Sciences, 388421 Anand, Gujrat, India
| | - Jia Li
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - Monika A Molenda
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - Adedamola A Opalade
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - William W Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, United States
| | | | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ferman A Chavez
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
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