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Bhat AP, Pomerantz WCK, Arnold WA. Fluorinated Pharmaceutical and Pesticide Photolysis: Investigating Reactivity and Identifying Fluorinated Products by Combining Computational Chemistry, 19F NMR, and Mass Spectrometry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 38340057 PMCID: PMC10883306 DOI: 10.1021/acs.est.3c09341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Fluorinated breakdown products from photolysis of pharmaceuticals and pesticides are of environmental concern due to their potential persistence and toxicity. While mass spectrometry workflows have been shown to be useful in identifying products, they fall short for fluorinated products and may miss up to 90% of products. Studies have shown that 19F NMR measurements assist in identifying and quantifying reaction products, but this protocol can be further developed by incorporating computations. Density functional theory was used to compute 19F NMR shifts for parent and product structures in photolysis reactions. Computations predicted NMR spectra of compounds with an R2 of 0.98. Computed shifts for several isolated product structures from LC-HRMS matched the experimental shifts with <0.7 ppm error. Multiple products including products that share the same shift that were not previously reported were identified and quantified using computational shifts, including aliphatic products in the range of -80 to -88 ppm. Thus, photolysis of fluorinated pharmaceuticals and pesticides can result in compounds that are polyfluorinated alkyl substances (PFAS), including aliphatic-CF3 or vinyl-CF2 products derived from heteroaromatic-CF3 groups. C-F bond-breaking enthalpies and electron densities around the fluorine motifs agreed well with the experimentally observed defluorination of CF3 groups. Combining experimental-computational 19F NMR allows quantification of products identified via LC-HRMS without the need for authentic standards. These results have applications for studies of environmental fate and analysis of fluorinated pharmaceuticals and pesticides in development.
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Affiliation(s)
- Akash P Bhat
- Department of Civil, Environmental, and Geo- Engineering University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - William A Arnold
- Department of Civil, Environmental, and Geo- Engineering University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455, United States
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Kaur R, Nikkel DJ, Aboelnga MM, Wetmore SD. The Impact of DFT Functional, Cluster Model Size, and Implicit Solvation on the Structural Description of Single-Metal-Mediated DNA Phosphodiester Bond Cleavage: The Case Study of APE1. J Phys Chem B 2022; 126:10672-10683. [PMID: 36485014 DOI: 10.1021/acs.jpcb.2c06756] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Phosphodiester bond hydrolysis in nucleic acids is a ubiquitous reaction that can be facilitated by enzymes called nucleases, which often use metal ions to achieve catalytic function. While a two-metal-mediated pathway has been well established for many enzymes, there is growing support that some enzymes require only one metal for the catalytic step. Using human apurinic/apyrimidinic endonuclease (APE1) as a prototypical example and cluster models, this study clarifies the impact of DFT functional, cluster model size, and implicit solvation on single-metal-mediated phosphodiester bond cleavage and provides insight into how to efficiently model this chemistry. Initially, a model containing 69 atoms built from a high-resolution X-ray crystal structure is used to explore the reaction pathway mapped by a range of DFT functionals and basis sets, which provides support for the use of standard functionals (M06-2X and B3LYP-D3) to study this reaction. Subsequently, systematically increasing the model size to 185 atoms by including additional amino acids and altering residue truncation points highlights that small models containing only a few amino acids or β carbon truncation points introduce model strains and lead to incorrect metal coordination. Indeed, a model that contains all key residues (general base and acid, residues that stabilize the substrate, and amino acids that maintain the metal coordination) is required for an accurate structural depiction of the one-metal-mediated phosphodiester bond hydrolysis by APE1, which results in 185 atoms. The additional inclusion of the broader enzyme environment through continuum solvation models has negligible effects. The insights gained in the present work can be used to direct future computational studies of other one-metal-dependent nucleases to provide a greater understanding of how nature achieves this difficult chemistry.
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Affiliation(s)
- Rajwinder Kaur
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Dylan J Nikkel
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Mohamed M Aboelnga
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada.,Chemistry Department, Faculty of Science, Damietta University, New Damietta 34517, Egypt
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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Fei Y, Liu Z, Meng L, Liu G, Kong D, Pan X, Zhu F, Lu J, Chen J. Experimental and theoretical study on Fe(VI) oxidative degradation of dichlorophen in water: Kinetics and reaction mechanisms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 306:119394. [PMID: 35525513 DOI: 10.1016/j.envpol.2022.119394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 04/25/2022] [Accepted: 04/30/2022] [Indexed: 06/14/2023]
Abstract
Dichlorophenol (DCP), a commonly used fungicide and insecticide, is widely found in waters and wastewaters. Herein, the degradation of DCP by Ferrate (Fe(VI)) in different matrices was comprehensively investigated. In pure water, a complete removal of DCP was achieved in 300 s at [Fe(VI)]:[DCP] molar ratio of 2:1. The presence of HA (10 mg L-1) inhibited DCP degradation to a certain extent. A total of twenty degradation products were identified by HPLC/MS analysis. Based on these products, reaction pathways including the cleavage of C-C bridge bond, hydroxylation, and radical coupling were proposed. These reaction mechanisms were further rationalized by theoretical calculations. The analyses of Wiberg bond orders and transition state indicated that C7-C8 bond was the most vulnerable site for cleavage, and C12 site was the most likely site for hydroxyl addition. Mulliken atomic spin densities distribution suggested that self-coupling products was easily generated via C-O-C coupling ways. Finally, the feasibility of applying Fe(VI) to degrade DCP (20 μM) in a municipal wastewater effluent and a lake water was evaluated and verified. The findings in this study are of relevance in designing Fe(VI)-based treatment strategy for chlorine-containing persistent pesticides.
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Affiliation(s)
- Yi Fei
- Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhuangzhuang Liu
- Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing, 210095, China
| | - Liang Meng
- Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing, 210095, China
| | - Guoqiang Liu
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing, 210042, China
| | - Deyang Kong
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing, 210042, China
| | - Xiaoxue Pan
- School of Resources and Environmental Engineering, Anhui University, Anhui, 230601, China
| | - Feng Zhu
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, 210023, China
| | - Junhe Lu
- Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jing Chen
- Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing, 210095, China.
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Sun X, Zhuang J, Ma X, Tang Y, Ali MM, Lu Z, Zheng X, Du Z. Structure elucidation and risk assessment of degradation products in gamma irradiated rubber closures. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.110126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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F.G.M. Cimirro N, Lima EC, Cunha MR, Thue PS, Grimm A, dos Reis GS, Rabiee N, Reza Saeb M, Keivanimehr F, Habibzadeh S. Removal of diphenols using pine biochar. Kinetics, equilibrium, thermodynamics, and mechanism of uptake. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119979] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Liu J, Fan XR, Zhao W, Yang SW, Hu B, Yang SG, Lu Q. Mechanical insight into the formation of H 2S from thiophene pyrolysis: The influence of H 2O. CHEMOSPHERE 2021; 279:130628. [PMID: 34134421 DOI: 10.1016/j.chemosphere.2021.130628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/05/2021] [Accepted: 04/18/2021] [Indexed: 06/12/2023]
Abstract
The thermal utilization of waste rubber is accompanied by the release of sulfur, and the release of H2S to the gas phase is one of the crucial issues. In this work, density functional theory (DFT) calculations and wave function analysis were employed to explore the possible formation pathways of H2S and its precursor (·SH radical) during the pyrolysis of thiophene in the presence of H2O. It indicates that H2O affects the decomposition of thiophene and the formation of H2S in two patterns. First, H2O can participate in the hydrogen transfer process by acting as a catalyst or generating weak hydrogen bonds with thiophene. In this way, the hydrogen transfer reactions are promoted with lower energy barriers, and thus the formation of H2S is facilitated by H2O without changing the pyrolysis pathways. Secondly, H2O can saturate the thiophene ring by addition reactions and alter the generation pathways of H2S significantly. The energy barriers can be decreased with one or two CC bonds of thiophene being saturated. The completely saturated thiophene results in a greater decline of the overall energy barriers for H2S formation. H2O provides the H atom for H2S in the second pattern. Due to the combination of the two influence patterns, the release of H2S can be promoted greatly in the presence of H2O. The present study aims to lay a foundation for the clean thermal utilization of thiophene/rubber and to inspire the advance of desulfurization techniques.
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Affiliation(s)
- Ji Liu
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China; China Energy Engineering Group Anhui Electric Power Design Institute, Co., LTD, Hefei, Anhui Province, 230601, PR China
| | - Xin-Rui Fan
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China
| | - Wei Zhao
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China
| | - Shuang-Wei Yang
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China
| | - Bin Hu
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China
| | - Shi-Guan Yang
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China
| | - Qiang Lu
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing, 102206, PR China.
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