1
|
Das A, Datta A. Oriented External Electric Field Controls the Rupture Forces in Mechanophores. J Phys Chem B 2024. [PMID: 38973239 DOI: 10.1021/acs.jpcb.4c02337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Controlling the reactivity of molecules under a mechanical pull has generated significant interest in organic and polymer chemistry. Inducing mechano-lability for otherwise rigid molecules has been possible through structural alterations like adjusting the pulling group, ring strain, and electron density of the scissile bond. In this article, we report that an oriented external electric field (OEEF) can significantly assist in mechanochemical transformations. Using a structurally diverse set of ring-opening reactions, 1(a)-4(a), we show that the critical force required for bond-cleavage, Frup, gets appreciably reduced when the OEEF acts in-phase with the bond-polarity direction. The primary condition for utilizing OEEF along with mechanochemistry is the requirement of structural asymmetry along the target bond. Effectively therefore, any polar ring-opening reaction might be manipulated by OEEF. The versatility of the strategy of using OEEF and mechanical force together can also be appreciated by the enhanced rupture force when the direction of the OEEF is flipped. We show that mechanical pulling and electric field can act as entwined twins toward mechano-lability.
Collapse
Affiliation(s)
- Ankita Das
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, West Bengal 700032, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, West Bengal 700032, India
| |
Collapse
|
2
|
Cao Y, Hay S, de Visser SP. An Active Site Tyr Residue Guides the Regioselectivity of Lysine Hydroxylation by Nonheme Iron Lysine-4-hydroxylase Enzymes through Proton-Coupled Electron Transfer. J Am Chem Soc 2024; 146:11726-11739. [PMID: 38636166 PMCID: PMC11066847 DOI: 10.1021/jacs.3c14574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/05/2024] [Accepted: 04/05/2024] [Indexed: 04/20/2024]
Abstract
Lysine dioxygenase (KDO) is an important enzyme in human physiology involved in bioprocesses that trigger collagen cross-linking and blood pressure control. There are several KDOs in nature; however, little is known about the factors that govern the regio- and stereoselectivity of these enzymes. To understand how KDOs can selectively hydroxylate their substrate, we did a comprehensive computational study into the mechanisms and features of 4-lysine dioxygenase. In particular, we selected a snapshot from the MD simulation on KDO5 and created large QM cluster models (A, B, and C) containing 297, 312, and 407 atoms, respectively. The largest model predicts regioselectivity that matches experimental observation with rate-determining hydrogen atom abstraction from the C4-H position, followed by fast OH rebound to form 4-hydroxylysine products. The calculations show that in model C, the dipole moment is positioned along the C4-H bond of the substrate and, therefore, the electrostatic and electric field perturbations of the protein assist the enzyme in creating C4-H hydroxylation selectivity. Furthermore, an active site Tyr233 residue is identified that reacts through proton-coupled electron transfer akin to the axial Trp residue in cytochrome c peroxidase. Thus, upon formation of the iron(IV)-oxo species in the catalytic cycle, the Tyr233 phenol loses a proton to the nearby Asp179 residue, while at the same time, an electron is transferred to the iron to create an iron(III)-oxo active species. This charged tyrosyl residue directs the dipole moment along the C4-H bond of the substrate and guides the selectivity to the C4-hydroxylation of the substrate.
Collapse
Affiliation(s)
- Yuanxin Cao
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department
of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sam Hay
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department
of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sam P. de Visser
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department
of Chemical Engineering, The University
of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| |
Collapse
|
3
|
Hardy FG, Wong HPH, de Visser SP. Computational Study Into the Oxidative Ring-Closure Mechanism During the Biosynthesis of Deoxypodophyllotoxin. Chemistry 2024; 30:e202400019. [PMID: 38323740 DOI: 10.1002/chem.202400019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/08/2024]
Abstract
The nonheme iron dioxygenase deoxypodophyllotoxin synthase performs an oxidative ring-closure reaction as part of natural product synthesis in plants. How the enzyme enables the oxidative ring-closure reaction of (-)-yatein and avoids substrate hydroxylation remains unknown. To gain insight into the reaction mechanism and understand the details of the pathways leading to products and by-products we performed a comprehensive computational study. The work shows that substrate is bound tightly into the substrate binding pocket with the C7'-H bond closest to the iron(IV)-oxo species. The reaction proceeds through a radical mechanism starting with hydrogen atom abstraction from the C7'-H position followed by ring-closure and a final hydrogen transfer to form iron(II)-water and deoxypodophyllotoxin. Alternative mechanisms including substrate hydroxylation and an electron transfer pathway were explored but found to be higher in energy. The mechanism is guided by electrostatic perturbations of charged residues in the second-coordination sphere that prevent alternative pathways.
Collapse
Affiliation(s)
- Fintan G Hardy
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Henrik P H Wong
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Sam P de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| |
Collapse
|
4
|
Lake WR, Meng J, Dawlaty JM, Lian T, Hammes-Schiffer S. Electro-inductive Effect Dominates Vibrational Frequency Shifts of Conjugated Probes on Gold Electrodes. J Am Chem Soc 2023; 145:22548-22554. [PMID: 37795975 DOI: 10.1021/jacs.3c07489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
Interfacial electric fields play a critical role in electrocatalysis and are often characterized by using vibrational probes attached to an electrode surface. Understanding the physical principles dictating the impact of the applied electrode potential on the vibrational probe frequency is important. Herein, a comparative study is performed for two molecular probes attached to a gold electrode. Both probes contain a nitrile (CN) group, but 4-mercaptobenzonitrile (4-MBN) exhibits continuous conjugation from the electrode through the nitrile group, whereas this conjugation is interrupted for 2-(4-mercaptophenyl)acetonitrile (4-MPCN). Periodic density functional theory calculations predict that the CN vibrational frequency shift of the 4-MBN system is dominated by induction, which is a through-bond polarization effect, leading to a strong potential dependence that does not depend significantly on the orientation of the CN bond relative to the surface. In contrast, the CN vibrational frequency shift of the 4-MPCN system is influenced less by induction and more by through-space electric field effects, leading to a weaker potential dependence and a greater orientation dependence. These theoretical predictions were confirmed by surface-enhanced Raman spectroscopy experiments. Balancing through-bond and through-space electrostatic effects may assist in the fundamental understanding and design of electrocatalytic systems.
Collapse
Affiliation(s)
- William R Lake
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Jinhui Meng
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Jahan M Dawlaty
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | | |
Collapse
|
5
|
Zhu C, Pham LN, Yuan X, Ouyang H, Coote ML, Zhang X. High Electric Fields on Water Microdroplets Catalyze Spontaneous and Fast Reactions in Halogen-Bond Complexes. J Am Chem Soc 2023; 145:21207-21212. [PMID: 37724917 DOI: 10.1021/jacs.3c08818] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
The use of external electric fields as green and efficient catalysts in synthetic chemistry has recently received significant attention for their ability to deliver remarkable control of reaction selectivity and acceleration of reaction rates. Technically, methods of generating high electric fields in the range of 1-10 V/nm are limited, as in-vacuo techniques have obvious scalability issues. The spontaneous high fields at various interfaces promise to solve this problem. In this study, we take advantage of the spontaneous high electric field at the air-water interface of sprayed water microdroplets in the reactions of several halogen bond systems: Nu:--X-X, where Nu: is pyridine or quinuclidine and X is bromine or iodine. The field facilitates ultrafast electron transfer from Nu:, yielding a Nu-X covalent bond and causing the X-X bond to cleave. This reaction occurs in microseconds in microdroplets but takes days to weeks in bulk solution. Density functional theory calculations predict that the reaction becomes barrier-free in the presence of oriented external electric fields, supporting the notion that the electric fields in the water droplets are responsible for the catalysis. We anticipate that microdroplet chemistry will be an avenue rich in opportunities in the reactions facilitated by high electric fields and provides an alternative way to tackle the scalability problem.
Collapse
Affiliation(s)
- Chenghui Zhu
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin, 300071, China
- Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
| | - Le Nhan Pham
- Institute for Nanoscale Science & Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Xu Yuan
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin, 300071, China
- Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
| | - Haoran Ouyang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin, 300071, China
- Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
| | - Michelle L Coote
- Institute for Nanoscale Science & Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Xinxing Zhang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin, 300071, China
- Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
| |
Collapse
|
6
|
Gopakumar K, Shaik S, Ramanan R. Two-Way Catalysis in a Diels-Alder Reaction Limits Inhibition Induced by an External Electric Field. Angew Chem Int Ed Engl 2023; 62:e202307579. [PMID: 37530131 DOI: 10.1002/anie.202307579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/18/2023] [Accepted: 08/01/2023] [Indexed: 08/03/2023]
Abstract
Oriented external electric fields (EEFs) act as catalysts that can induce selectivity in chemical reactions. The responses of the Diels-Alder (DA) reaction between butadiene and ethylene (BDE-DA) as well as cyclopentadiene and ethylene (CPDE-DA) towards EEF stimuli are investigated here using density functional theory (B3LYP) calculations. EEF is a vector that catalyzes the reaction in one direction while inhibiting it in the opposite direction. Here we report that the inhibitive direction becomes rate-enhancing after some increase in the EEF. The EEF value that brings about the maximum possible inhibition for the reaction is defined as the electrostatic resistance point (ERP). The possibility of both normal and inverse electron-demand DA reactions causes catalytic activity in both directions of the EEF starting at a unique ERP value. The C5 substituents of cyclopentadiene control the ERP values depending upon the resistance power that the functional group provides against the EEF. The endo and exo diastereomeric transition states of the DA reaction have distinct ERP values and the difference (ΔERP) provides the through-space electrostatic contribution to the stereoselectivity on a relative scale. Thus, the ERP values can be used as a gauge for the electrostatic interactions between substituent groups and external stimuli.
Collapse
Affiliation(s)
- Karthik Gopakumar
- Department of Chemistry, National Institute of Technology, Rourkela, Rourkela, Odisha, 769008, India
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, 9190407, Jerusalem, Israel
| | - Rajeev Ramanan
- Department of Chemistry, National Institute of Technology, Rourkela, Rourkela, Odisha, 769008, India
| |
Collapse
|
7
|
Shiels OJ, Marlton SJP, Trevitt AJ. Protonation Isomer Specific Ion-Molecule Radical Reactions. J Am Chem Soc 2023. [PMID: 37339086 DOI: 10.1021/jacs.3c02552] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Through a combination of ion-mobility filtering and laser-equipped quadrupole ion-trap mass spectrometry, the gas-phase reaction kinetics of two protonation isomers of the distonic-radical quinazoline cation are independently measured with ethylene. For these radical addition reactions, protonation site variations drive significant changes in nearby radical reactivity, and this is primarily due to through-space electrostatic effects. Furthermore, quantum chemical methods specifically designed for calculating long-range interactions, such as double-hybrid density functional theory, are required to rationalize the experimentally measured difference in reactivity.
Collapse
Affiliation(s)
- Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, New South Wales, Australia
| | - Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, New South Wales, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, New South Wales, Australia
| |
Collapse
|
8
|
Akerman M, Iny H, Sagi R, Asscher M. Chemical Reactivity of Strongly Interacting, Hydrogen-Bond-Forming Molecules Following 193 nm Photon Irradiation: Methanol in Amorphous Solid Water at Low Temperatures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:2838-2849. [PMID: 36763094 PMCID: PMC9948533 DOI: 10.1021/acs.langmuir.2c03441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Mixtures of methanol and amorphous solid water (ASW) ices are observed in the interstellar medium (ISM), where they are subject to irradiation by UV photons and bombardment by charged particles. The charged particles, if at high enough density, induce a local electric field in the ice film that potentially affects the photochemistry of these ices. When CD3OD@ASW ices grown at 38 K on a Ru(0001) substrate are irradiated by 193 nm (6.4 eV) photons, products such as HD, D2, CO, and CO2 are formed in large abundances relative to the initial amount of CD3OD. Other molecules such as D2O, CD4, acetaldehyde, and ethanol and/or dimethyl ether are also observed, but in smaller relative abundances. The reactivity cross sections range from (2.6 ± 0.3) × 10-21 to (3.8 ± 0.3) × 10-25 cm2/photon. The main products are formed through two competing mechanisms: direct photodissociation of methanol and water and dissociative electron attachment (DEA) by photoelectrons ejected from the Ru(0001) substrate. An electric field of 2 × 108 V/m generated within the ASW film during Ne+ ions bombardment is apparently not strong enough to affect the relative abundances (selectivity) of the photochemical products observed in this study.
Collapse
|
9
|
Kempfer-Robertson EM, Avdic I, Haase MN, Pike TD, Thompson LM. Protonation state control of electric field induced molecular switching mechanisms. Phys Chem Chem Phys 2023; 25:5251-5261. [PMID: 36723228 DOI: 10.1039/d2cp04494c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Scanning tunneling microscopy tip-induced deprotonation has been demonstrated experimentally and can be used as an additional control mechanism in electric-field induced molecular switching. The goal of the current work is to establish whether (de)protonation can be used to inhibit or enhance the electric field controlled thermal and photoisomerization processes. Dihydroxyazobenzene is used as a model system, where protonation/deprotonation of the free hydroxyl moiety changes the azo bond order, and so modifies the rate of electric field induced isomerization. Through the combined action of deprotonation and applied field, it was found that the cis-to-trans thermal isomerization barrier could be completely removed, changing the isomerization half-life from the order of several months. In addition, due to the presence of multiple isomerization mechanisms, electric fields could modify the isomerization kinetics by increasing the number of energetically viable isomerization pathways, rather than reducing the activation barrier of the lowest energy pathway. Excited state calculations indicated that the protonation state and electric field could be used together to control the presence of electronic degeneracies along the rotation pathway between S0/S1, and along all three pathways between S1/S2. This work provides insight into the mechanisms that enable the use of protonation state, light, and electric fields in concert to control molecular switches.
Collapse
Affiliation(s)
| | - Irma Avdic
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Meagan N Haase
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Thomas Dane Pike
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Lee M Thompson
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| |
Collapse
|
10
|
Hajra C, Mandal S, Datta A. External Electric Field Induces a Mechanistic Crossover in the Reactivity of 1,3-Dienes with Sulfur Dioxide: Sulfolene Versus Sultine. J Org Chem 2023; 88:917-923. [PMID: 36598469 DOI: 10.1021/acs.joc.2c02302] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
1,3-Dienes (1) react with SO2 to produce sulfolenes (2) and sultines (3). Previous experiments and computational studies have shown that hetero-Diels-Alder (HDA) reaction producing the sultine is kinetically favorable compared to the chelotropic (CE) reaction producing the sulfolene. In this article, DFT calculations for a series of substituted 1,3-dienes show that under the influence of a moderate oriented external electric field (OEEF) of 2.0-4.0 V nm-1 along the reaction axis, the chelotropic reaction becomes the kinetically favorable reaction. In the absence of the OEEF, the destabilizing distortion involved in bringing the 1,3-diene and SO2 to the CE transition-state (TS) exceeds than for the HDA TS. However, under the influence of the OEEF, the strongly stabilizing electrostatic interactions in the CE TS effectively overcome the structural distortion energy. The enhanced dipole moment of the CE TS vis-à-vis the HDA TS under the OEEF accounts for the stabilization of the former.
Collapse
Affiliation(s)
- Chandralekha Hajra
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur─700032Kolkata, West Bengal, India
| | - Sucharita Mandal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur─700032Kolkata, West Bengal, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur─700032Kolkata, West Bengal, India
| |
Collapse
|
11
|
Blyth MT, Coote ML. Manipulation of N-heterocyclic carbene reactivity with practical oriented electric fields. Phys Chem Chem Phys 2023; 25:375-383. [DOI: 10.1039/d2cp04507a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Electric fields can be used to tune the nucleophilicity and electrophilicity of N-heterocyclic carbenes and enhance their catalytic activity.
Collapse
Affiliation(s)
- Mitchell T. Blyth
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L. Coote
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| |
Collapse
|
12
|
Chin C, Zhu T, Zhang JZH. Theoretical study of the absorption and emission spectrum and non‐adiabatic excited state dynamics of gas‐phase xanthone. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202200422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Chih‐Hao Chin
- School of Chemistry and Molecular Engineering East China Normal University Shanghai China
- NYU‐ECNU Center for Computational Chemistry at NYU Shanghai Shanghai China
| | - Tong Zhu
- School of Chemistry and Molecular Engineering East China Normal University Shanghai China
- NYU‐ECNU Center for Computational Chemistry at NYU Shanghai Shanghai China
| | - John Zeng Hui Zhang
- School of Chemistry and Molecular Engineering East China Normal University Shanghai China
- NYU‐ECNU Center for Computational Chemistry at NYU Shanghai Shanghai China
- Shenzhen Institute of Synthetic Biology and Faculty of Synthetic Biology Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences Shenzhen China
| |
Collapse
|
13
|
Weberg AB, Murphy RP, Tomson NC. Oriented internal electrostatic fields: an emerging design element in coordination chemistry and catalysis. Chem Sci 2022; 13:5432-5446. [PMID: 35694353 PMCID: PMC9116365 DOI: 10.1039/d2sc01715f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/19/2022] [Indexed: 11/21/2022] Open
Abstract
The power of oriented electrostatic fields (ESFs) to influence chemical bonding and reactivity is a phenomenon of rapidly growing interest. The presence of strong ESFs has recently been implicated as one of the most significant contributors to the activity of select enzymes, wherein alignment of a substrate's changing dipole moment with a strong, local electrostatic field has been shown to be responsible for the majority of the enzymatic rate enhancement. Outside of enzymology, researchers have studied the impacts of "internal" electrostatic fields via the addition of ionic salts to reactions and the incorporation of charged functional groups into organic molecules (both experimentally and computationally), and "externally" via the implementation of bulk fields between electrode plates. Incorporation of charged moieties into homogeneous inorganic complexes to generate internal ESFs represents an area of high potential for novel catalyst design. This field has only begun to materialize within the past 10 years but could be an area of significant impact moving forward, since it provides a means for tuning the properties of molecular complexes via a method that is orthogonal to traditional strategies, thereby providing possibilities for improved catalytic conditions and novel reactivity. In this perspective, we highlight recent developments in this area and offer insights, obtained from our own research, on the challenges and future directions of this emerging field of research.
Collapse
Affiliation(s)
- Alexander B Weberg
- R, oy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 S. 34th Street Philadelphia Pennsylvania 19104 USA
| | - Ryan P Murphy
- R, oy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 S. 34th Street Philadelphia Pennsylvania 19104 USA
| | - Neil C Tomson
- R, oy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 S. 34th Street Philadelphia Pennsylvania 19104 USA
| |
Collapse
|
14
|
Wang JYJ, Blyth MT, Sherburn MS, Coote ML. Tuning Photoenolization-Driven Cycloadditions Using Theory and Spectroscopy. J Am Chem Soc 2022; 144:1023-1033. [PMID: 34991316 DOI: 10.1021/jacs.1c12174] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The first broad spectrum investigation into the photoenolization/Diels-Alder (PEDA) sequence was carried out using M06-2X/6-31+G(d,p) in conjunction with SMD solvation and supported by experimental UV-vis spectroscopy. A test set of 20 prodienes was chosen to examine the role of the H atom acceptor group (substituted and unsubstituted carbonyl, thiocarbonyl, and imine), the H atom donor group, and bystander ring substituents. As reaction partners for the photogenerated dienes, a diverse test set of 20 dienophiles was examined, comprising electron rich, electron poor, neutral, strain activated, hydrocarbon, and heteroatom-containing molecules including CO2 and CO. A key finding of this work is the demonstration that the PEDA sequence of carbonyl based prodienes is tolerant of most substitution patterns. Another is that thiocarbonyl derivatives should behave analogously to the carbonyls but are likely to do so much more slowly, due to an inefficient intersystem crossing, an endothermic 1,5-hydrogen atom transfer (HAT) step, and a [1,5] sigmatropic H shift to regenerate the starting material that outcompetes the [4 + 2]cycloaddition. In contrast, the T1 state of the ortho-alkyl imines displays the incorrect orbital symmetry for 1,5-HAT and is correspondingly accompanied by higher barriers, even in the excited state. However, provided these barriers can be overcome, the remaining steps in the PEDA sequence are predicted to be facile. The Diels-Alder reaction is predicted to be of much broader scope than reported synthetic literature: while electron poor dienophiles are expected to be the most reactive partners, ethylene and electron rich alkenes should react at a synthetically useful rate. CO is predicted to undergo a facile (4 + 1)cheletropic addition instead of the normal [4 + 2]cycloaddition pathway. This unique photoenolization/cheletropic addition (PECA) sequence could provide metal-free access to benzannelated cyclopentanones.
Collapse
Affiliation(s)
- Jiao Yu J Wang
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Mitchell T Blyth
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michael S Sherburn
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L Coote
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
15
|
de Visser SP, Mukherjee G, Ali HS, Sastri CV. Local Charge Distributions, Electric Dipole Moments, and Local Electric Fields Influence Reactivity Patterns and Guide Regioselectivities in α-Ketoglutarate-Dependent Non-heme Iron Dioxygenases. Acc Chem Res 2022; 55:65-74. [PMID: 34915695 DOI: 10.1021/acs.accounts.1c00538] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Non-heme iron dioxygenases catalyze vital processes for human health related to the biosynthesis of essential products and the biodegradation of toxic metabolites. Often the natural product biosyntheses by these non-heme iron dioxygenases is highly regio- and chemoselective, which are commonly assigned to tight substrate-binding and positioning. However, recent high-level computational modeling has shown that substrate-binding and positioning is only part of the story and long-range electrostatic interactions can play a major additional role.In this Account, we review and summarize computational viewpoints on the high regio- and chemoselectivity of α-ketoglutarate-dependent non-heme iron dioxygenases and how external perturbations affect the catalysis. In particular, studies from our groups have shown that often a regioselectivity in enzymes can be accomplished by stabilization of the rate-determining transition state for the reaction through external charges, electric dipole moments, or local electric field effects. Furthermore, bond dissociation energies in molecules are shown to be influenced by an electric field effect, and through targeting a specific bond in an electric field, this can lead to an unusually specific reaction. For instance, in the carbon-induced starvation protein, we studied two substrate-bound conformations and showed that regardless of what C-H bond of the substrate is closest to the iron(IV)-oxo oxidant, the lowest hydrogen atom abstraction barrier is always for the pro-S C2-H abstraction due to an induced dipole moment of the protein that weakens this bond. In another example of the hygromycin biosynthesis enzyme, an oxidative ring-closure reaction in the substrate forms an ortho-δ-ester ring. Calculations on this enzyme show that the selectivity is guided by a protonated lysine residue in the active site that, through its positive charge, triggers a low energy hydrogen atom abstraction barrier. A final set of examples in this Account discuss the viomycin biosynthesis enzyme and the 2-(trimethylammonio)ethylphosphonate dioxygenase (TmpA) enzyme. Both of these enzymes are shown to possess a significant local dipole moment and local electric field effect due to charged residues surrounding the substrate and oxidant binding pockets. The protein dipole moment and local electric field strength changes the C-H bond strengths of the substrate as compared to the gas-phase triggers the regioselectivity of substrate activation. In particular, we show that in the gas phase and in a protein environment C-H bond strengths are different due to local electric dipole moments and electric field strengths. These examples show that enzymes have an intricately designed structure that enables a chemical reaction under ambient conditions through the positioning of positively and negatively charged residues that influence and enhance reaction mechanisms. These computational insights create huge possibilities in bioengineering to apply local electric field and dipole moments in proteins to achieve an unusual selectivity and specificity and trigger a fit-for-purpose biocatalyst for unique biotransformations.
Collapse
Affiliation(s)
- Sam P. de Visser
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
| | - Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
| | - Hafiz Saqib Ali
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Chivukula V. Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
| |
Collapse
|
16
|
Ali HS, de Visser S, de Visser SP. Electrostatic perturbations in the substrate-binding pocket of taurine/α-ketoglutarate dioxygenase determine its selectivity. Chemistry 2021; 28:e202104167. [PMID: 34967481 PMCID: PMC9304159 DOI: 10.1002/chem.202104167] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Indexed: 11/17/2022]
Abstract
Taurine/α‐ketoglutarate dioxygenase is an important enzyme that takes part in the cysteine catabolism process in the human body and selectively hydroxylates taurine at the C1‐position. Recent computational studies showed that in the gas‐phase the C2−H bond of taurine is substantially weaker than the C1−H bond, yet no evidence exists of 2‐hydroxytaurine products. To this end, a detailed computational study on the selectivity patterns in TauD was performed. The calculations show that the second‐coordination sphere and the protonation states of residues play a major role in guiding the enzyme to the right selectivity. Specifically, a single proton on an active site histidine residue can change the regioselectivity of the reaction through its electrostatic perturbations in the active site and effectively changes the C1−H and C2−H bond strengths of taurine. This is further emphasized by many polar and hydrogen bonding interactions of the protein cage in TauD with the substrate and the oxidant that weaken the pro‐R C1−H bond and triggers a chemoselective reaction process. The large cluster models reproduce the experimental free energy of activation excellently.
Collapse
Affiliation(s)
- Hafiz Saqib Ali
- The University of Manchester, School of Chemistry, UNITED KINGDOM
| | - Samuel de Visser
- The University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, M1 7DN, Manchester, UNITED KINGDOM
| | - Sam P de Visser
- The University of Manchester, Department of Chemical Engineering, UNITED KINGDOM
| |
Collapse
|
17
|
Alías-Rodríguez M, de Graaf C, Huix-Rotllant M. Ultrafast Intersystem Crossing in Xanthone from Wavepacket Dynamics. J Am Chem Soc 2021; 143:21474-21477. [PMID: 34905690 DOI: 10.1021/jacs.1c07039] [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
Most aromatic ketones containing first-row elements undergo unexpectedly fast intersystem crossing in a few tens of picoseconds and a quantum yield close to unity. Among them, xanthone (9H-xanthen-9-one) possesses one of the fastest singlet-triplet rates of only ∼1.5 ps. The exact mechanism of this unusually fast transition is still under debate. Here, we perform wavepacket dynamics of the photochemistry of xanthone in the gas phase and in polar solvents. We show that xanthone follows El-Sayed's rule for intersystem crossing. From the second singlet excited state, the mechanism is sequential: (i) an internal conversion between singlets 1ππ* → 1nπ* (85 fs), (ii) an intersystem crossing 1nπ* → 3ππ* (2.0 ps), and (iii) an internal conversion between triplets 3ππ* → 3nπ* (602 fs). Each transfer finds its origin in a barrierless access to electronic state intersections. These intersections are close to minimum energy structures, allowing for efficient transitions from the initial singlet state to the triplets.
Collapse
Affiliation(s)
- Marc Alías-Rodríguez
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo 1, Tarragona 43 007, Spain.,Aix-Marseille Univ, CNRS, ICR, Marseille 13 397, France
| | - Coen de Graaf
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo 1, Tarragona 43 007, Spain.,ICREA, Passeig Lluís Companys 23, Barcelona 08 010, Spain
| | | |
Collapse
|
18
|
Besalú-Sala P, Solà M, Luis JM, Torrent-Sucarrat M. Fast and Simple Evaluation of the Catalysis and Selectivity Induced by External Electric Fields. ACS Catal 2021. [DOI: 10.1021/acscatal.1c04247] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Pau Besalú-Sala
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Josep M. Luis
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Catalonia, Spain
| | - Miquel Torrent-Sucarrat
- Department of Organic Chemistry I, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), P Manuel Lardizabal 3, E-20018 Donostia/San Sebastián, Euskadi, Spain
- Ikerbasque, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Euskadi, Spain
| |
Collapse
|
19
|
Marlton SJP, McKinnon BI, Greißel P, Shiels OJ, Ucur B, Trevitt AJ. Picosecond excited-state lifetimes of protonated indazole and benzimidazole: The role of the N-N bond. J Chem Phys 2021; 155:184302. [PMID: 34773941 DOI: 10.1063/5.0071847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Certain chemical groups give rise to characteristic excited-state deactivation mechanisms. Here, we target the role of a protonated N-N chemical group in the excited-state deactivation of protonated indazole by comparison to its isomer that lacks this group, protonated benzimidazole. Gas-phase protonated indazole and protonated benzimidazole ions are investigated at room temperature using picosecond laser pump-probe photodissociation experiments in a linear ion-trap. Excited state lifetimes are measured across a range of pump energies (4.0-5.4 eV). The 1ππ* lifetimes of protonated indazole range from 390 ± 70 ps using 4.0 eV pump energy to ≤18 ps using 4.6 eV pump energy. The 1ππ* lifetimes of protonated benzimidazole are systematically longer, ranging from 3700 ± 1100 ps at 4.6 eV pump energy to 400 ± 200 ps at 5.4 eV. Based on these experimental results and accompanying quantum chemical calculations and potential energy surfaces, the shorter lifetimes of protonated indazole are attributed to πσ* state mediated elongation of the protonated N-N bond.
Collapse
Affiliation(s)
- Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Benjamin I McKinnon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Phillip Greißel
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Boris Ucur
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| |
Collapse
|
20
|
Avdic I, Kempfer-Robertson EM, Thompson LM. Oriented External Electric Field Tuning of Unsubstituted Azoheteroarene Thermal Isomerization Half-Lives. J Phys Chem A 2021; 125:8238-8248. [PMID: 34494847 DOI: 10.1021/acs.jpca.1c06102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Azoheteroarenes are relatively new photoswitchable compounds, where one of the phenyl rings of an azobenzene molecule is replaced by a heteroaromatic five-membered ring. Recent findings on methylated azoheteroarenes show that these photoswitches have potential in various optically addressable applications. The thermal stability of molecular switches is one of the primary factors considered in the design process. For molecular memory or energy storage devices, long thermal relaxation times are required. However, inducing a short thermal isomerization lifetime is required to release stored energy or as an alternative to photoswitching to avoid overlapping absorption spectra that reduce switching fidelity. In this study, we investigate how oriented external electric fields can be used to tune the thermal isomerization properties of three unsubstituted heteroaryl azo compounds-azoimidazole, azopyrazole, and azopyrrole. We show that favorable electric field orientations can increase the thermal half-life of studied molecules by as much as 60 times or reduce it from tens of days to seconds, compared to their half-life values in the field-free environment. A deeper understanding of the relationship between structure and kinetic properties provides insight as to how molecular switches can be designed for their electric field response in switching applications.
Collapse
Affiliation(s)
- Irma Avdic
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, United States
| | | | - Lee M Thompson
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, United States
| |
Collapse
|
21
|
Ramanan R, Waheed SO, Schofield CJ, Christov CZ. What Is the Catalytic Mechanism of Enzymatic Histone N-Methyl Arginine Demethylation and Can It Be Influenced by an External Electric Field? Chemistry 2021; 27:11827-11836. [PMID: 33989435 DOI: 10.1002/chem.202101174] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Indexed: 11/11/2022]
Abstract
Arginine methylation is an important mechanism of epigenetic regulation. Some Fe(II) and 2-oxoglutarate dependent Jumonji-C (JmjC) Nϵ-methyl lysine histone demethylases also have N-methyl arginine demethylase activity. We report combined molecular dynamic (MD) and Quantum Mechanical/Molecular Mechanical (QM/MM) studies on the mechanism of N-methyl arginine demethylation by human KDM4E and compare the results with those reported for N-methyl lysine demethylation by KDM4A. At the KDM4E active site, Glu191, Asn291, and Ser197 form a conserved scaffold that restricts substrate dynamics; substrate binding is also mediated by an out of active site hydrogen-bond between the substrate Ser1 and Tyr178. The calculations imply that in either C-H or N-H potential bond cleaving pathways for hydrogen atom transfer (HAT) during N-methyl arginine demethylation, electron transfer occurs via a σ-channel; the transition state for the N-H pathway is ∼10 kcal/mol higher than for the C-H pathway due to the higher bond dissociation energy of the N-H bond. The results of applying external electric fields (EEFs) reveal EEFs with positive field strengths parallel to the Fe=O bond have a significant barrier-lowering effect on the C-H pathway, by contrast, such EEFs inhibit the N-H activation rate. The overall results imply that KDM4 catalyzed N-methyl arginine demethylation and N-methyl lysine demethylation occur via similar C-H abstraction and rebound mechanisms leading to methyl group hydroxylation, though there are differences in the interactions leading to productive binding of intermediates.
Collapse
Affiliation(s)
- Rajeev Ramanan
- Department of Chemistry, Michigan Technological University, Houghton, Michigan, 49931, USA.,Present address: Department of Chemistry, National Institute of Technology, Rourkela, Odisha, 769001, India
| | - Sodiq O Waheed
- Department of Chemistry, Michigan Technological University, Houghton, Michigan, 49931, USA
| | - Christopher J Schofield
- The Department of Chemistry and the Ineos Oxford Institute for, Antimicrobial Research, The Chemistry Research Laboratory, University of Oxford, Mansfield Road, OX1 5JJ, Oxford, UK
| | - Christo Z Christov
- Department of Chemistry, Michigan Technological University, Houghton, Michigan, 49931, USA
| |
Collapse
|
22
|
Abstract
Density functional theory (DFT) has been employed in predicting the enantioselectivity of the aldol reaction between acetone and p-nitrobenzaldehyde catalyzed by proline and its derivatives Me2bdc-Pro (bdc = 1,4-benzenedicarboxylate) and Me2bpdc-Pro (bpdc = 4,4'-biphenyldicarboxylate). For each catalyst, our computationally predicted values at the M062X/6-31+G(d) level of theory with the SMD solvent model are in excellent agreement with experimental results reported in the literature. Electron-donating and electron-withdrawing groups (viz., SO3-, NMe2, SO3H, and NMe3+) were installed at the C4 position of the proline-based catalysts to study the impact of electrostatic effects on stereoselectivity. The electron-donating groups decrease and even invert the enantioselectivity, while the electron-withdrawing ones increase it. Enantiomeric excesses in the range of 49-71 and 59-68% are predicted for Me2bdc-Pro and Me2bpdc-Pro catalysts with the electron-withdrawing SO3H and NMe3+ installed respectively, values much higher than those of the corresponding unmodified catalysts. More interestingly, enantiomeric excesses decrease and, in the case of SO3-, are even inverted in favor of the other enantiomer when the electron-donating groups are installed. These results highlight the importance of electrostatic effects, and polar effects more generally, in optimal organocatalyst design for stereoselective C-C bond-forming reactions.
Collapse
Affiliation(s)
- Li-Juan Yu
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
23
|
Zhu D, Wagner P, Xiao P. Terthiophene Derivative-Based Photoinitiating Systems for Free Radical and Cationic Polymerization under Blue LEDs. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c00743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Di Zhu
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Pawel Wagner
- ARC Centre of Excellence for Electromaterials Science and the Intelligent Polymer Research Institute, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Pu Xiao
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
24
|
Robertson PA, Bishop HM, Orr-Ewing AJ. Tuning the Excited-State Dynamics of Acetophenone Using Metal Ions in Solution. J Phys Chem Lett 2021; 12:5473-5478. [PMID: 34085833 DOI: 10.1021/acs.jpclett.1c01466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The effects of dissolved metal salts on the excited-state dynamics of acetophenone in solution have been explored by using ultrafast transient absorption spectroscopy at two UV excitation wavelengths. In the absence of metal ions, the S1(nπ*) transition of acetophenone is excited at 320 nm, with intersystem crossing (ISC) occurring with a time constant τISC = 5.95 ± 0.47 ps in acetonitrile solution. Excitation at 280 nm accesses the S2(ππ*) state, which internally converts (<0.2 ps) to S1 before undergoing ISC with τISC = 4.36 ± 0.14 ps. Coordination to Mg2+ ions makes the S2 state accessible to excitation at 320 nm, with the rate of S2 → S1 internal conversion reducing 3-fold but the ISC rate increasing. These changes to the excited-state energies and dynamics of this model photosensitizer indicate that dissolved metal salts could modify the photochemistry of synthetically useful homogeneous photocatalytic systems.
Collapse
Affiliation(s)
- Patrick A Robertson
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Hannah M Bishop
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| |
Collapse
|
25
|
Lin YT, Ali HS, de Visser SP. Electrostatic Perturbations from the Protein Affect C-H Bond Strengths of the Substrate and Enable Negative Catalysis in the TmpA Biosynthesis Enzyme. Chemistry 2021; 27:8851-8864. [PMID: 33978257 DOI: 10.1002/chem.202100791] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Indexed: 11/08/2022]
Abstract
The nonheme iron dioxygenase 2-(trimethylammonio)-ethylphosphonate dioxygenase (TmpA) is an enzyme involved in the regio- and chemoselective hydroxylation at the C1 -position of the substrate as part of the biosynthesis of glycine betaine in bacteria and carnitine in humans. To understand how the enzyme avoids breaking the weak C2 -H bond in favor of C1 -hydroxylation, we set up a cluster model of 242 atoms representing the first and second coordination sphere of the metal center and substrate binding pocket, and investigated possible reaction mechanisms of substrate activation by an iron(IV)-oxo species by density functional theory methods. In agreement with experimental product distributions, the calculations predict a favorable C1 -hydroxylation pathway. The calculations show that the selectivity is guided through electrostatic perturbations inside the protein from charged residues, external electric fields and electric dipole moments. In particular, charged residues influence and perturb the homolytic bond strength of the C1 -H and C2 -H bonds of the substrate, and strongly strengthens the C2 -H bond in the substrate-bound orientation.
Collapse
Affiliation(s)
- Yen-Ting Lin
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.,Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Hafiz Saqib Ali
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Sam P de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.,Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| |
Collapse
|
26
|
Marlton SJP, McKinnon BI, Hill NS, Coote ML, Trevitt AJ. Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding. J Am Chem Soc 2021; 143:2331-2339. [PMID: 33427467 DOI: 10.1021/jacs.0c11978] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The low-lying electronic states of Irgacure 2959, a Norrish-type I photoinitiator, complexed with a single metal cation are investigated in the gas phase by photodissociation action spectroscopy. Analysis of the band shifts using quantum chemical calculations (TD-DFT and SCS-CC2) reveals the underlying influence of the charge on the key electronic energy levels. Since the cations (H+, Li+, Na+, K+, Zn2+, Ca2+, and Mg2+) bind at varying distances, the magnitude of the electric field at the center of the chromophore due to the cation is altered, and this shifts the electronic states by different amounts. Photodissociation action spectra of cation-Irg complexes show that absorption transitions to the first 1ππ* state are red-shifted with a magnitude proportional to the electric field strength (with red shifts >1 eV), and in most cases, the cation is essentially acting as a point charge. Calculations show that a neighboring 3nπ* state, a key state for the α-cleavage pathway, is destabilized (blue-shifted) by the orientated electric field. As such, if the 1ππ*-3nπ* energy gap is reduced, increased intersystem crossing rates are expected, resulting in higher yields of the desired radical photoproducts, and this is controlled by the orientated electric field arising from the cation.
Collapse
Affiliation(s)
- Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Benjamin I McKinnon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nicholas S Hill
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| |
Collapse
|
27
|
Weberg AB, McCollom SP, Thierer LM, Gau MR, Carroll PJ, Tomson NC. Using internal electrostatic fields to manipulate the valence manifolds of copper complexes. Chem Sci 2021; 12:4395-4404. [PMID: 34163703 PMCID: PMC8179517 DOI: 10.1039/d0sc06364a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A series of tetradentate tris(phosphinimine) ligands (R3P3tren) was developed and bound to CuI to form the trigonal pyramidal, C3v-symmetric cuprous complexes [R3P3tren-Cu][BArF4] (1PR3) (PR3 = PMe3, PMe2Ph, PMePh2, PPh3, PMe2(NEt2), BArF4 = B(C6F5)4). Electrochemical studies on the CuI complexes were undertaken, and the permethylated analog, 1PMe3, was found to display an unprecedentedly cathodic CuI/CuII redox potential (−780 mV vs. Fc/Fc+ in isobutyronitrile). Elucidation of the electronic structures of 1PR3via density functional theory (DFT) studies revealed atypical valence manifold configurations, resulting from strongly σ-donating phosphinimine moieties in the xy-plane that destabilize 2e (dxy/dx2−y2) orbital sets and uniquely stabilized a1 (dz2) orbitals. Support is provided that the a1 stabilizations result from intramolecular electrostatic fields (ESFs) generated from cationic character on the phosphinimine moieties in R3P3tren. This view is corroborated via 1-dimensional electrostatic potential maps along the z-axes of 1PR3 and their isostructural analogues. Experimental validation of this computational model is provided upon oxidation of 1PMe3 to the cupric complex [Me3P3tren-Cu][OTf]2 (2PMe3), which displays a characteristic Jahn–Teller distortion in the form of a see-saw, pseudo-Cs-symmetric geometry. A systematic anodic shift in the potential of the CuI/CuII redox couple as the steric bulk in the secondary coordination sphere increases is explained through the complexes' diminishing ability to access the ideal Cs-symmetric geometry upon oxidation. The observations and calculations discussed in this work support the presence of internal electrostatic fields within the copper complexes, which subsequently influence the complexes' properties via a method orthogonal to classic ligand field tuning. Secondary coordination sphere electrostatic effects tune the valence manifolds of copper centers, impacting molecular geometries, photophysical properties, and redox potentials.![]()
Collapse
Affiliation(s)
- Alexander B Weberg
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| | - Samuel P McCollom
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| | - Laura M Thierer
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| | - Michael R Gau
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| | - Patrick J Carroll
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| | - Neil C Tomson
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104 USA
| |
Collapse
|
28
|
Sugiyama H, Sato S, Nagai K. Sterically Photo-induced Fluorine-containing Polyimide: a Gaussian-based Three-dimensional Structural Approach of Photo Alignment Film. J PHOTOPOLYM SCI TEC 2021. [DOI: 10.2494/photopolymer.34.571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Shuichi Sato
- Department of Electronic Engineering, Tokyo Denki University
| | | |
Collapse
|
29
|
Laconsay CJ, Mallick D, Shaik S. External Electric Fields Interrupt the Concerted Cope Rearrangement of Semibullvalene. J Org Chem 2020; 86:731-738. [PMID: 33280381 DOI: 10.1021/acs.joc.0c02322] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The topic of this paper is whether the mechanism of the degenerate Cope rearrangement of semibullvalene can be affected by the presence of electrostatic fields. Herein, we report that the shape of the energy surface, as demonstrated by an "interrupted" (stepwise) mechanism, is altered in the presence of a copper cation, Cu+. Natural bond-orbital and block-localized wave-function energy decomposition analyses suggest that orbital and electrostatic interactions play a major role in altering the shape of the energy surface. Applying additional external electric fields (EEFs) induces a significant change to the energy surface with Cu+ present but negligible effects in the absence of Cu+. These findings are consistent with recent studies that demonstrate that EEFs more readily stabilize/destabilize systems with larger, more polarizable, dipole moments.
Collapse
Affiliation(s)
- Croix J Laconsay
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.,Department of Chemistry, University of California-Davis, 1 Shields Avenue, Davis, California 95616, United States
| | - Dibyendu Mallick
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.,Department of Chemistry, Presidency University, Kolkata 700073, India
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| |
Collapse
|
30
|
Abstract
Photoactivation of tetrazoles to form nitrile imines primed for 1,3-dipolar cycloaddition reactions is of widespread utility in chemistry. In contrast, the corresponding thermal reactions usually possess prohibitively high barriers and have garnered significantly less attention. Here, computational chemistry at the M06-2X/6-31+G(d,p) level of theory with SMD solvent corrections is used to show that these thermal activation barriers can be significantly reduced through the use of nonconjugated charged functional groups (CFGs). For 2,5-dimethyl-tetrazole, a positive CFG on the N-methyl (2-position) lowers the fragmentation barrier by around 80 kJ mol-1 in the gas phase, while a negative charge has a smaller opposite effect. These CFG effects remain significant even in polar solvents, with barrier lowering on the order of 30 kJ mol-1 in dimethyl sulfoxide and acetonitrile. In practical terms, the positive CFG decreases the fragmentation half-life of 2,5-dimethyl-tetrazole in refluxing o-xylene from 300,000 years to 1 week. While the resulting nitrile imine is stabilized, its subsequent 1,3-cycloaddition with N-methylmaleimide remains highly facile. Electrostatic effects on a range of 2-phenyl-5-methyltetrazoles, 2-methyl-5-phenyl-tetrazoles, and 2,5-diphenyl-tetrazoles follow similar trends and are explicable largely in terms of the stabilization of the developing dipole in the transition state.
Collapse
Affiliation(s)
- Vincent Doan
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Benjamin B Noble
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
31
|
Xu L, Izgorodina EI, Coote ML. Ordered Solvents and Ionic Liquids Can Be Harnessed for Electrostatic Catalysis. J Am Chem Soc 2020; 142:12826-12833. [PMID: 32610899 DOI: 10.1021/jacs.0c05643] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Herein, we employ classical molecular dynamics simulations using the Drude oscillator-based polarizable force field, quantum chemical calculations, and ONIOM multiscale calculations to study (a) how an external field orders the solvent environment in a chemical reaction and then (b) whether in the absence of this same applied field the ordered solvent environment alone can electrostatically catalyze a chemical reaction when compared with the corresponding disordered solvent. Our results show that a 0.2 V/Å external electric field, which is below the threshold for bond breaking of solvent molecules, leads to significant ordering of bulk methanol solvent and the ionic liquid [EMIM][BF4]. Importantly, in the absence of this same field, the ordered solvent lowers the activation energy of the hydrogen-transfer reaction of o-alkylphenyl ketones in excess of 20 kcal/mol when the solvent is methanol and by over 30 kcal/mol for [EMIM][BF4]. Even a 0.1 V/Å external field has effects of ca. 10 and 20 kcal/mol, respectively. This work suggests a possible strategy for scaling electrostatic catalysis by applying a pulsed external field to the reaction medium to maintain solvent ordering while allowing the reaction to proceed largely in the absence of an external field.
Collapse
Affiliation(s)
- Longkun Xu
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Ekaterina I Izgorodina
- Monash Computational Chemistry Group, School of Chemistry, Monash University, 17 Rainforest Walk, Clayton, Victoria 3800, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
32
|
Marlton SJP, McKinnon BI, Ucur B, Bezzina JP, Blanksby SJ, Trevitt AJ. Discrimination between Protonation Isomers of Quinazoline by Ion Mobility and UV-Photodissociation Action Spectroscopy. J Phys Chem Lett 2020; 11:4226-4231. [PMID: 32368922 DOI: 10.1021/acs.jpclett.0c01009] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The influence of oriented electric fields on chemical reactivity and photochemistry is an area of increasing interest. Within a molecule, different protonation sites offer the opportunity to control the location of charge and thus orientation of electric fields. New techniques are thus needed to discriminate between protonation isomers in order to understand this effect. This investigation reports the UV-photodissociation action spectroscopy of two protonation isomers (protomers) of 1,3-diazanaphthalene (quinazoline) arising from protonation of a nitrogen at either the 1- or 3-position. It is shown that these protomers are separable by field-asymmetric ion mobility spectrometry (FAIMS) with confirmation provided by UV-photodissociation (PD) action spectroscopy. Vibronic features in the UVPD action spectra and computational input allow assignment of the origin transitions to the S1 and S5 states of both protomers. These experiments also provide vital benchmarks for protomer-specific calculations and examination of isomer-resolved reaction kinetics and thermodynamics.
Collapse
Affiliation(s)
- Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Benjamin I McKinnon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Boris Ucur
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - James P Bezzina
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Stephen J Blanksby
- Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane 4001, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| |
Collapse
|
33
|
Kempfer-Robertson EM, Thompson LM. Effect of Oriented External Electric Fields on the Photo and Thermal Isomerization of Azobenzene. J Phys Chem A 2020; 124:3520-3529. [PMID: 32286821 DOI: 10.1021/acs.jpca.0c00492] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Azobenzene is a prototype molecule with potential applications in molecular switches, solar thermal batteries, sensors, photoresponsive membranes, molecular electronics, data storage, and nonlinear optics. Photo and thermal isomerization pathways exhibit different charge-transfer character and dipole moments, implying that the use of electric fields can be used to modulate the reactivity of azobenzene. This article examines the differential effect of orientated electric fields on the rotation and inversion thermal and photoisomerization pathways of azobenzene to explore the feasibility of using electric fields in the design of azobenzene-based molecular devices. Our findings demonstrate that the application of orientated electric fields modifies the accessibility of the S0/S1 seam of electronic degeneracy, as well as changes the energetically favored relaxation pathway in the branching space to yield different photoproducts. In addition, we observed strong-field dipole-inversion effects that cause a topographical change in the response of the potential energy surface to the applied field and can result in geometric minima that do not exist under field-free conditions. On the S0 surface, transition barriers can be modified on the order of ±10 kcal mol-1, enabling control of thermal isomerization rates.
Collapse
Affiliation(s)
| | - Lee M Thompson
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40205, United States
| |
Collapse
|
34
|
Joy J, Stuyver T, Shaik S. Oriented External Electric Fields and Ionic Additives Elicit Catalysis and Mechanistic Crossover in Oxidative Addition Reactions. J Am Chem Soc 2020; 142:3836-3850. [DOI: 10.1021/jacs.9b11507] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Jyothish Joy
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Thijs Stuyver
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- Algemene Chemie, Vrije Universiteit Brussel, Pleinlaan 2, Brussels 1050, Belgium
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| |
Collapse
|
35
|
Blyth MT, Noble BB, Russell IC, Coote ML. Oriented Internal Electrostatic Fields Cooperatively Promote Ground- and Excited-State Reactivity: A Case Study in Photochemical CO2 Capture. J Am Chem Soc 2019; 142:606-613. [DOI: 10.1021/jacs.9b12186] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mitchell T. Blyth
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Benjamin B. Noble
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Isabella C. Russell
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
36
|
Stuyver T, Danovich D, Joy J, Shaik S. External electric field effects on chemical structure and reactivity. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2019. [DOI: 10.1002/wcms.1438] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Thijs Stuyver
- Institute of Chemistry The Hebrew University Jerusalem Israel
- Algemene Chemie Vrije Universiteit Brussel Brussels Belgium
| | - David Danovich
- Institute of Chemistry The Hebrew University Jerusalem Israel
| | - Jyothish Joy
- Institute of Chemistry The Hebrew University Jerusalem Israel
| | - Sason Shaik
- Institute of Chemistry The Hebrew University Jerusalem Israel
| |
Collapse
|
37
|
Hill NS, Coote ML. Strategies for Red-Shifting Type I Photoinitiators: Internal Electric Fields versus Lewis Acids versus Increasing Conjugation. Aust J Chem 2019. [DOI: 10.1071/ch19262] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Time-dependent density functional theory calculations were performed on derivatives of Irgacure 2959, a water-soluble, acetophenone-type photoinitiator, in order to assess the relative merits and drawbacks of three distinct ways of modifying its photochemistry: Lewis acid complexation, changing the amount of conjugation in the molecule, and application of an internal electric field through inclusion of a remote charged functional group. The effectiveness of each of the three methods was evaluated against the magnitude of the change in energy of the excited states. Internal electric fields were shown to provide the best method for targeting specific excited states in a controlled and rational manner. The other strategies also had significant effects but it was more difficult to independently target different transitions. Nonetheless, for the specific case of Irgacure 2959, we predict that its complexation with Mg2+ ions in a range of solvents will both red-shift the initiator’s absorbance while improving its efficiency and it is thus a promising candidate for testing as a visible light photoinitiator.
Collapse
|
38
|
Zhu L, Mohamed H, Yuan H, Zhang J. The control effects of different scaffolds in chiral phosphoric acids: a case study of enantioselective asymmetric arylation. Catal Sci Technol 2019. [DOI: 10.1039/c9cy01420a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
DFT calculations disclosed that the sign of enantioselectivity in chiral-phosphoric-acid catalyzed reactions can be tuned by BINOL- or SPINOL-derived backbones.
Collapse
Affiliation(s)
- Lihan Zhu
- Faculty of Chemistry
- Northeast Normal University
- Changchun
- P. R. China
| | - Hend Mohamed
- Faculty of Chemistry
- Northeast Normal University
- Changchun
- P. R. China
| | - Haiyan Yuan
- Faculty of Chemistry
- Northeast Normal University
- Changchun
- P. R. China
| | - Jingping Zhang
- Faculty of Chemistry
- Northeast Normal University
- Changchun
- P. R. China
| |
Collapse
|
39
|
Affiliation(s)
- Li-Juan Yu
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|