1
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Mildner M, Hanio S, Endres S, Scheller L, Engel B, Castañar L, Meinel L, Pöppler AC. In situ setup for screening of drug permeation by NMR spectroscopy. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2024; 16:1468-1472. [PMID: 38226670 DOI: 10.1039/d3ay01995k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
There are various commercially available setups for studying drug permeation, which differ in cost and manual labor. We explore an artificial membrane in an NMR tube to assess drug permeation with automated measurements. NMR-based concentrations were validated with HPLC and compared to a conventional setup. Setup-specific challenges and workarounds as well as future setup-designs for this and other applications are discussed.
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Affiliation(s)
- Malte Mildner
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany.
| | - Simon Hanio
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Sebastian Endres
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany.
| | - Lena Scheller
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Bettina Engel
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Laura Castañar
- Department of Organic Chemistry, Faculty of Chemical Science, Complutense University of Madrid, Madrid, Spain
| | - Lorenz Meinel
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Ann-Christin Pöppler
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany.
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2
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Li S, Bhattacharya S, Chou CY, Chu M, Chou SC, Tonelli M, Goger M, Yang H, Palmer AG, Cavagnero S. LC-Photo-CIDNP hyperpolarization of biomolecules bearing a quasi-isolated spin pair: Magnetic-Field dependence via a rapid-shuttling device. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 359:107616. [PMID: 38271744 PMCID: PMC10922348 DOI: 10.1016/j.jmr.2023.107616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/27/2024]
Abstract
Liquid-state low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) is an emerging technology tailored to enhance the sensitivity of NMR spectroscopy via LED- or laser-mediated optical irradiation. LC-photo-CIDNP is particularly useful to detect solvent-exposed aromatic residues (Trp, Tyr), either in isolation or within polypeptides and proteins. This study investigates the magnetic-field dependence of the LC-photo-CIDNP of Trp-α-13C-β,β,2,4,5,6,7-d7, a Trp isotopolog bearing a quasi-isolated 1Hα-13Cαspin pair (QISP). We employed a new rapid-shuttling side-illumination field-cycling device that enables ultra-fast (90-120 ms) vertical movements of NMR samples within the bore of a superconducting magnet. Thus, LC-photo-CIDNP hyperpolarization occurs at low field, while hyperpolarized signals are detected at high field (700 MHz). Resonance lineshapes were excellent, and the effect of several fields (1.18-7.08 T range) on hyperpolarization efficiency could be readily explored. Remarkably, unprecedented LC-photo-CIDNP enhancements ε ≅ 1,200 were obtained at 50 MHz (1.18 T), suggesting exciting avenues to hypersensitive LED-enhanced NMR in liquids at low field.
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Affiliation(s)
- Siyu Li
- Dept. of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | | | - Ching-Yu Chou
- Field Cycling Technology LTD., New Taipei City 23444, Taiwan, ROC
| | - Minglee Chu
- Institute of Physics, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Shu-Cheng Chou
- Field Cycling Technology LTD., New Taipei City 23444, Taiwan, ROC
| | - Marco Tonelli
- Dept. of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Michael Goger
- New York Structural Biology Center, New York, NY 10027, United States
| | - Hanming Yang
- Dept. of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Arthur G Palmer
- New York Structural Biology Center, New York, NY 10027, United States; Dept. of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, United States
| | - Silvia Cavagnero
- Dept. of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United States.
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3
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Swords WB, Lee H, Park Y, Llamas F, Skubi KL, Park J, Guzei IA, Baik MH, Yoon TP. Highly Enantioselective 6π Photoelectrocyclizations Engineered by Hydrogen Bonding. J Am Chem Soc 2023; 145:27045-27053. [PMID: 38049954 PMCID: PMC10842740 DOI: 10.1021/jacs.3c10782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
Photochemical electrocyclization reactions are valued for both their ability to produce structurally complex molecules and their central role in elucidating fundamental mechanistic principles of photochemistry. We present herein a highly enantioselective 6π photoelectrocyclization catalyzed by a chiral Ir(III) photosensitizer. This transformation was successfully realized by engineering a strong hydrogen-bonding interaction between a pyrazole moiety on the catalyst and a basic imidazolyl ketone on the substrate. To shed light on the origin of stereoinduction, we conducted a comprehensive investigation combining experimental and computational mechanistic studies. Results from density functional theory calculations underscore the crucial role played by the prochirality and the torquoselectivity in the electrocyclization process as well as the steric demand in the subsequent [1,4]-H shift step. Our findings not only offer valuable guidance for developing chiral photocatalysts but also serve as a significant reference for achieving high levels of enantioselectivity in the 6π photoelectrocyclization reaction.
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Affiliation(s)
- Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Hanna Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Yerin Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Franco Llamas
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Kazimer L Skubi
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- Department of Chemistry, Carleton College, Northfield, Minnesota 55057, United States
| | - Jiyong Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Ilia A Guzei
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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4
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LaPorte AJ, Feldner JE, Spies JC, Maher TJ, Burke MD. MIDA- and TIDA-Boronates Stabilize α-Radicals Through B-N Hyperconjugation. Angew Chem Int Ed Engl 2023; 62:e202309566. [PMID: 37540542 DOI: 10.1002/anie.202309566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/05/2023]
Abstract
Multifunctional organoboron compounds increasingly enable the simple generation of complex, Csp3 -rich small molecules. The ability of boron-containing functional groups to modify the reactivity of α-radicals has also enabled a myriad of chemical reactions. Boronic esters with vacant p-orbitals have a significant stabilizing effect on α-radicals due to delocalization of spin density into the empty orbital. The effect of coordinatively saturated derivatives, such as N-methyliminodiacetic acid (MIDA) boronates and counterparts, remains less clear. Herein, we demonstrate that coordinatively saturated MIDA and TIDA boronates stabilize secondary alkyl α-radicals via σB-N hyperconjugation in a manner that allows site-selective C-H bromination. DFT calculated radical stabilization energies and spin density maps as well as LED NMR kinetic analysis of photochemical bromination rates of different boronic esters further these findings. This work clarifies that the α-radical stabilizing effect of boronic esters does not only proceed via delocalization of radical character into vacant boron p-orbitals, but that hyperconjugation of tetrahedral boron-containing functional groups and their ligand electron delocalizing ability also play a critical role. These findings establish boron ligands as a useful dial for tuning reactivity at the α-carbon.
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Affiliation(s)
- Antonio J LaPorte
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Jack E Feldner
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Jan C Spies
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Tom J Maher
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Martin D Burke
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
- Carle Illinois College of Medicine, University of Illinois, Urbana, IL, 61820, USA
- Department of Biochemistry, University of Illinois, Urbana, IL, 61820, USA
- Arnold and Mable Beckman Institute, University of Illinois, Urbana, IL, 61820, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, 61820, USA
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5
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Smith MJ, Bramham JE, Nilsson M, Morris GA, Castañar L, Golovanov AP. Lighting up spin systems: enhancing characteristic 1H signal patterns of fluorinated molecules. Chem Commun (Camb) 2023; 59:11692-11695. [PMID: 37698544 DOI: 10.1039/d3cc03557c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Fluorine is becoming increasingly prevalent in medicinal chemistry, both in drug molecules and in molecular probes. The presence of fluorine allows convenient monitoring of such molecules in complex environments by NMR spectroscopy. However, sensitivity is a persistent limitation of NMR, especially when molecules are present at low concentrations. Here, sensitivity issues with 1H NMR are mitigated by sharing 19F photochemically-induced dynamic nuclear polarisation with 1H nuclei. Unlike direct 1H enhancement, this method enhances 1H signals without significantly distorting multiplet intensities, and has the potential to enable the use of suitable molecules as low-concentration probes.
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Affiliation(s)
- Marshall J Smith
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Jack E Bramham
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Mathias Nilsson
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Gareth A Morris
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Laura Castañar
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Department of Organic Chemistry, Faculty of Chemical Science, Complutense University of Madrid, Ciudad Universitaria s/n, Madrid 28040, Spain.
| | - Alexander P Golovanov
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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6
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Glotz G, Püschmann S, Haas M, Gescheidt G. Direct detection of photo-induced reactions by IR: from Brook rearrangement to photo-catalysis. Photochem Photobiol Sci 2023:10.1007/s43630-023-00406-4. [PMID: 36933157 DOI: 10.1007/s43630-023-00406-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/28/2023] [Indexed: 03/19/2023]
Abstract
In situ IR detection of photoreactions induced by the light of LEDs at appropriate wavelengths provides a simple, cost-effective, and versatile method to get insight into mechanistic details. In particular, conversions of functional groups can be selectively followed. Overlapping UV-Vis bands or fluorescence from the reactants and products and the incident light do not obstruct IR detection. Compared with in situ photo-NMR, our setup does not require tedious sample preparation (optical fibers) and offers a selective detection of reactions, even at positions where 1H-NMR lines overlap or 1H resonances are not clear-cut. We illustrate the applicability of our setup following the photo-Brook rearrangement of (adamant-1-yl-carbonyl)-tris(trimethylsilyl)silane, address photo-induced α-bond cleavage (1-hydroxycyclohexyl phenyl ketone), study photoreduction using tris(bipyridine)ruthenium(II), investigate photo-oxygenation of double bonds with molecular oxygen and the fluorescent 2,4,6-triphenylpyrylium photocatalyst, and address photo-polymerization. With the LED/FT-IR combination, reactions can be qualitatively followed in fluid solution, (highly) viscous environments, and in the solid state. Viscosity changes during the reaction (e.g., during a polymerization) do not obstruct the method.
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Affiliation(s)
- Gabriel Glotz
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/II, 8010, Graz, Austria.
| | - Sabrina Püschmann
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, 8010, Graz, Austria
| | - Michael Haas
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, 8010, Graz, Austria
| | - Georg Gescheidt
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/II, 8010, Graz, Austria
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7
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Paolillo JM, Duke AD, Gogarnoiu ES, Wise DE, Parasram M. Anaerobic Hydroxylation of C(sp 3)-H Bonds Enabled by the Synergistic Nature of Photoexcited Nitroarenes. J Am Chem Soc 2023; 145:2794-2799. [PMID: 36696364 PMCID: PMC10032565 DOI: 10.1021/jacs.2c13502] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A photoexcited-nitroarene-mediated anaerobic C-H hydroxylation of aliphatic systems is reported. The success of this reaction is due to the bifunctional nature of the photoexcited nitroarene, which serves as the C-H bond activator and the oxygen atom source. Compared to previous methods, this approach is cost- and atom-economical due to the commercial availability of the nitroarene, the sole mediator of the reaction. Because of the anaerobic conditions of the transformation, a noteworthy expansion in substrate scope can be obtained compared to prior reports. Mechanistic studies support that the photoexcited nitroarenes engage in successive hydrogen atom transfer and radical recombination events with hydrocarbons, leading to N-arylhydroxylamine ether intermediates. Spontaneous fragmentation of these intermediates leads to the key oxygen atom transfer products.
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Affiliation(s)
- Joshua M Paolillo
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Alana D Duke
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Emma S Gogarnoiu
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Dan E Wise
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Marvin Parasram
- Department of Chemistry, New York University, New York, New York 10003, United States
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8
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Eills J, Budker D, Cavagnero S, Chekmenev EY, Elliott SJ, Jannin S, Lesage A, Matysik J, Meersmann T, Prisner T, Reimer JA, Yang H, Koptyug IV. Spin Hyperpolarization in Modern Magnetic Resonance. Chem Rev 2023; 123:1417-1551. [PMID: 36701528 PMCID: PMC9951229 DOI: 10.1021/acs.chemrev.2c00534] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.
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Affiliation(s)
- James Eills
- Institute
for Bioengineering of Catalonia, Barcelona
Institute of Science and Technology, 08028Barcelona, Spain,
| | - Dmitry Budker
- Johannes
Gutenberg-Universität Mainz, 55128Mainz, Germany,Helmholtz-Institut,
GSI Helmholtzzentrum für Schwerionenforschung, 55128Mainz, Germany,Department
of Physics, UC Berkeley, Berkeley, California94720, United States
| | - Silvia Cavagnero
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Eduard Y. Chekmenev
- Department
of Chemistry, Integrative Biosciences (IBio), Karmanos Cancer Institute
(KCI), Wayne State University, Detroit, Michigan48202, United States,Russian
Academy of Sciences, Moscow119991, Russia
| | - Stuart J. Elliott
- Molecular
Sciences Research Hub, Imperial College
London, LondonW12 0BZ, United Kingdom
| | - Sami Jannin
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Anne Lesage
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Jörg Matysik
- Institut
für Analytische Chemie, Universität
Leipzig, Linnéstr. 3, 04103Leipzig, Germany
| | - Thomas Meersmann
- Sir
Peter Mansfield Imaging Centre, University Park, School of Medicine, University of Nottingham, NottinghamNG7 2RD, United Kingdom
| | - Thomas Prisner
- Institute
of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic
Resonance, Goethe University Frankfurt, , 60438Frankfurt
am Main, Germany
| | - Jeffrey A. Reimer
- Department
of Chemical and Biomolecular Engineering, UC Berkeley, and Materials Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
| | - Hanming Yang
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Igor V. Koptyug
- International Tomography Center, Siberian
Branch of the Russian Academy
of Sciences, 630090Novosibirsk, Russia,
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9
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van Venrooy A, Wyderka AM, García-López V, Alemany LB, Martí AA, Tour JM. Probing the Rotary Cycle of Amine-Substituted Molecular Motors. J Org Chem 2023; 88:762-770. [PMID: 36622748 DOI: 10.1021/acs.joc.2c01457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An understanding of the rotary cycle of molecular motors (MMs), a key component of an approach to opening cells using mechanical motion, is important in furthering the research. Nuclear magnetic resonance (NMR) spectroscopy was used for in situ analysis of illuminated light-active MMs. We found that the presence of a N,N-dimethylethylenediamine in a position conjugated to the central olefin results in changes to the rotation of a second-generation Feringa-type MM. Importantly, the addition decreases the photostability of the compound. The parent compound 1 can withstand >2 h of illumination with no signs of decomposition, while the amino 7 decomposes after 10 min. We found that the degradation can be mitigated by implementing the simple techniques of modulating the light dose, dilution, and stirring the sample while illuminating. Additionally, the presence of moisture affects the rate of the motor's rotation. The addition of the amino group to 1, without moisture present, makes the rotation of motor 7 three times slower than the unfunctionalized parent compound. We also report the use of a method that can be used to determine the molar extinction coefficient of a light-generated metastable species. This method can be used when in situ NMR illumination is not available.
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Affiliation(s)
- Alexis van Venrooy
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Aaron M Wyderka
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Víctor García-López
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Lawrence B Alemany
- Department of Chemistry, Rice University, Houston, Texas 77005, United States.,Shared Equipment Authority, Rice University, Houston, Texas 77005, United States
| | - Angel A Martí
- Department of Chemistry, Rice University, Houston, Texas 77005, United States.,Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.,Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - James M Tour
- Department of Chemistry, Rice University, Houston, Texas 77005, United States.,Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.,Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States.,NanoCarbon Center and the Welch Institute for Advanced Materials, Rice University, Houston, Texas 77005, United States
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10
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Bazzoni M, Lhoste C, Bonnet J, Konan KE, Bernard A, Giraudeau P, Felpin FX, Dumez JN. In-line Multidimensional NMR Monitoring of Photochemical Flow Reactions. Chemistry 2023; 29:e202203240. [PMID: 36651473 DOI: 10.1002/chem.202203240] [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: 10/17/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023]
Abstract
This work demonstrates the in-line monitoring of a flow photochemical reaction using 1D and ultrafast 2D NMR methods at high magnetic field. The reaction mixture exiting the flow reactor is flown through the NMR spectrometer and directly analyzed. In the case of simple substrates, suitable information can be obtained through 1D 1 H spectra, but for molecules of higher complexity the use of 2D experiments is key to address signal overlaps and assignment issues. Here we show the usefulness of ultrafast 2D COSY experiments acquired in 70 s or less, for the in-line monitoring of photochemical reactions, and the possibility to obtain reliable quantitative information. This is a powerful framework to, for example, efficiently screen reaction conditions.
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Affiliation(s)
| | - Célia Lhoste
- Nantes Université, CNRS, CEISAM UMR6230, F-4400, Nantes, France
| | - Justine Bonnet
- Nantes Université, CNRS, CEISAM UMR6230, F-4400, Nantes, France
| | | | - Aurélie Bernard
- Nantes Université, CNRS, CEISAM UMR6230, F-4400, Nantes, France
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11
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Brown E, Mandzhieva I, TomHon PM, Theis T, Castellano FN. Triplet Photosensitized para-Hydrogen Induced Polarization. ACS CENTRAL SCIENCE 2022; 8:1548-1556. [PMID: 36439314 PMCID: PMC9686209 DOI: 10.1021/acscentsci.2c01003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Indexed: 06/16/2023]
Abstract
Despite its enormous utility in structural characterization, nuclear magnetic resonance (NMR) spectroscopy is inherently limited by low spin polarization. One method to address the low polarization is para-hydrogen (p-H2) induced polarization (PHIP) which uses the singlet spin isomer of H2 to generate disparate nuclear spin populations to amplify the associated NMR signals. PHIP often relies on thermal catalysis or, more infrequently, UV-activated catalytic hydrogenation. Light-activated hydrogenation enables direct and timed control over the hyperpolarization of target substrates, critical for identifying short-lived intermediates. Here, we use an established Ir(III) triplet photosensitizer (PS) to visible light sensitize the triplet ligand-field states in the d6-transition metal dihydride Ru(CO)(PPh3)3(H)2 (1). Excitation inside a 9.4 T NMR spectrometer with the PS and a 420 nm blue LED, under 3 atm of p-H2, successfully photosensitized hyperpolarization in 1 and in a range of unsaturated substrates at and below room temperature, up to 1630-fold. In otherwise identical experimental conditions without light activation, no polarization was realized in 1 or the substrates evaluated. We believe triplet-sensitized PHIP (Trip-PHIP) represents a facile experimental means for probing triplet sensitized light activation in transition metal catalysts possessing low-lying triplet ligand-field states, providing mechanistic insight of potentially tremendous value in chemical catalysis.
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12
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Swords WB, Chapman SJ, Hofstetter H, Dunn AL, Yoon TP. Variable Temperature LED-NMR: Rapid Insights into a Photocatalytic Mechanism from Reaction Progress Kinetic Analysis. J Org Chem 2022; 87:11776-11782. [PMID: 35969669 DOI: 10.1021/acs.joc.2c01479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multitude of techniques are available to obtain a useful understanding of photocatalytic mechanisms. The combination of LED illumination with nuclear magnetic resonance spectroscopy (LED-NMR) provides a rapid, convenient means to directly monitor a photocatalytic reaction in situ. Herein, we describe a study of the mechanism of an enantioselective intermolecular [2 + 2] photocycloaddition catalyzed by a chiral Ir photocatalyst using LED-NMR. The data-rich output of this experiment is suitable for same-excess and variable time normalization analyses (VTNA). Together, these identified an unexpected change in mechanism between reactions conducted at ambient and cryogenic temperatures. At -78 °C, the kinetic data are consistent with the triplet rebound mechanism we previously proposed for this reaction, involving sensitization of maleimide and rapid reaction with a hydrogen-bound quinoline within the solvent cage. At room temperature, the cycloaddition instead proceeds through intracomplex energy transfer to the hydrogen-bound quinolone. These results highlight the potential sensitivity of photocatalytic reaction mechanisms to the precise reaction conditions and the further utility of LED-NMR as a fast, data-rich tool for their interrogation that compares favorably to conventional ex situ kinetic analyses.
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Affiliation(s)
- Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Steven J Chapman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Heike Hofstetter
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
| | - Anna L Dunn
- Drug Product Development, GlaxoSmithKline, Upper Providence, Pennsylvania19426, United States
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin53703, United States
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13
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Wise DE, Gogarnoiu ES, Duke AD, Paolillo JM, Vacala TL, Hussain WA, Parasram M. Photoinduced Oxygen Transfer Using Nitroarenes for the Anaerobic Cleavage of Alkenes. J Am Chem Soc 2022; 144:15437-15442. [PMID: 35930615 DOI: 10.1021/jacs.2c05648] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein we report the anaerobic cleavage of alkenes into carbonyl compounds using nitroarenes as oxygen transfer reagents under visible light. This approach serves as a safe and practical alternative to mainstream oxidative cleavage protocols, such as ozonolysis and the Lemieux-Johnson reaction. A wide range of alkenes possessing oxidatively sensitive functionalities underwent anaerobic cleavage to generate carbonyl derivatives with high efficiency and regioselectivity. Mechanistic studies support that the transformation occurs via direct photoexcitation of the nitroarene followed by a nonstereospecific radical cycloaddition event with alkenes. This leads to 1,3,2- and 1,4,2-dioxazolidine intermediates that fragment to give the carbonyl products. A combination of radical clock experiments and in situ photoNMR spectroscopy revealed the identities of the key radical species and the putative aryl dioxazolidine intermediates, respectively.
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Affiliation(s)
- Dan E Wise
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Emma S Gogarnoiu
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Alana D Duke
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Joshua M Paolillo
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Taylor L Vacala
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Waseem A Hussain
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
| | - Marvin Parasram
- Department of Chemistry, New York University, 24 Waverly Place, third floor, New York, New York 10003, United States
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14
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Sample illumination device facilitates in situ light-coupled NMR spectroscopy without fibre optics. Commun Chem 2022; 5:90. [PMID: 36697806 PMCID: PMC9814378 DOI: 10.1038/s42004-022-00704-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 07/13/2022] [Indexed: 01/28/2023] Open
Abstract
In situ illumination of liquid-state nuclear magnetic resonance (NMR) samples makes it possible for a wide range of light-dependent chemical and biological phenomena to be studied by the powerful analytical technique. However, the position of an NMR sample deep within the bore of the spectrometer magnet renders such illumination challenging. Here, we demonstrate the working principles of a sample illumination device (NMRtorch) where a lighthead containing an LED array is positioned directly at the top of an NMRtorch tube which is inserted into the NMR spectrometer. The wall of the tube itself acts as a light guide, illuminating the sample from the outside. We explore how this new setup performs in a number of photo-NMR applications, including photoisomerisation and photo-chemically induced dynamic nuclear polarisation (photo-CIDNP), and demonstrate the potential for ultraviolet (UV) degradation studies with continuous online NMR assessment. This setup enables users of any typical liquid-state spectrometer to easily perform in situ photo-NMR experiments, using a wide range of wavelengths.
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15
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Kristinaityte K, Mames A, Pietrzak M, Westermair FF, Silva W, Gschwind RM, Ratajczyk T, Urbańczyk M. Deeper Insight into Photopolymerization: The Synergy of Time-Resolved Nonuniform Sampling and Diffusion NMR. J Am Chem Soc 2022; 144:13938-13945. [PMID: 35852987 PMCID: PMC9354252 DOI: 10.1021/jacs.2c05944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The comprehensive real-time in situ monitoring of chemical
processes
is a crucial requirement for the in-depth understanding of these processes.
This monitoring facilitates an efficient design of chemicals and materials
with the precise properties that are desired. This work presents the
simultaneous utilization and synergy of two novel time-resolved NMR
methods, i.e., time-resolved diffusion NMR and time-resolved nonuniform
sampling. The first method allows the average diffusion coefficient
of the products to be followed, while the second method enables the
particular products to be monitored. Additionally, the average mass
of the system is calculated with excellent resolution using both techniques.
Employing both methods at the same time and comparing their results
leads to the unequivocal validation of the assignment in the second
method. Importantly, such validation is possible only via the simultaneous
combination of both approaches. While the presented methodology was
utilized for photopolymerization, it can also be employed for any
other polymerization process, complexation, or, in general, chemical
reactions in which the evolution of mass in time is of importance.
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Affiliation(s)
- Kristina Kristinaityte
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Adam Mames
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Franz F. Westermair
- Faculty of Chemistry and Pharmacy, Univeristy of Regensburg, Universitätsstraßze 31, 93053 Regensburg, Germany
| | - Wagner Silva
- Faculty of Chemistry and Pharmacy, Univeristy of Regensburg, Universitätsstraßze 31, 93053 Regensburg, Germany
| | - Ruth M. Gschwind
- Faculty of Chemistry and Pharmacy, Univeristy of Regensburg, Universitätsstraßze 31, 93053 Regensburg, Germany
| | - Tomasz Ratajczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Mateusz Urbańczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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16
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Cortelazzo-Polisini E, Boisbrun M, Gansmüller AH, Comoy C. Photoisomerization of Arylidene Heterocycles: Toward the Formation of Fused Heterocyclic Quinolines. J Org Chem 2022; 87:9699-9713. [PMID: 35801862 DOI: 10.1021/acs.joc.2c00748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report herein the photoinduced isomerization of a series of arylidene heterocycles 1. The photoreaction mechanism was investigated by a combined UV-vis/photo-NMR spectroscopic study, and we showed that Ar-TZDs exhibit a positive P-type photochromism, which limits their isomerization efficiency. By exploring the solvatochromism in a series of solvents, the conditions favoring the conversion toward one or the other stereoisomer have been studied, in particular by choosing the appropriate wavelengths. Finally, the extension of this photoisomerization study was proposed with a convenient preparation of various fused heterocyclic quinolines in good overall yields.
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Affiliation(s)
| | | | | | - Corinne Comoy
- Université de Lorraine, CNRS, L2CM, F-54000 Nancy, France
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17
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Corra S, Bakić MT, Groppi J, Baroncini M, Silvi S, Penocchio E, Esposito M, Credi A. Kinetic and energetic insights into the dissipative non-equilibrium operation of an autonomous light-powered supramolecular pump. NATURE NANOTECHNOLOGY 2022; 17:746-751. [PMID: 35760895 DOI: 10.1038/s41565-022-01151-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Natural and artificial autonomous molecular machines operate by constantly dissipating energy coming from an external source to maintain a non-equilibrium state. Quantitative thermodynamic characterization of these dissipative states is highly challenging as they exist only as long as energy is provided. Here we report on the detailed physicochemical characterization of the dissipative operation of a supramolecular pump. The pump transduces light energy into chemical energy by bringing self-assembly reactions to non-equilibrium steady states. The composition of the system under light irradiation was followed in real time by 1H NMR for four different irradiation intensities. The experimental composition and photon flow were then fed into a theoretical model describing the non-equilibrium dissipation and the energy storage at the steady state. We quantitatively probed the relationship between the light energy input and the deviation of the dissipative state from thermodynamic equilibrium in this artificial system. Our results provide a testing ground for newly developed theoretical models for photoactivated artificial molecular machines operating away from thermodynamic equilibrium.
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Affiliation(s)
- Stefano Corra
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy
- Dipartimento di Chimica Industriale 'Toso Montanari', Università di Bologna, Bologna, Italy
| | - Marina Tranfić Bakić
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy
- Dipartimento di Chimica Industriale 'Toso Montanari', Università di Bologna, Bologna, Italy
| | - Jessica Groppi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy
| | - Massimo Baroncini
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy
- Dipartimento di Scienze e Tecnologie Agro-alimentari, Università di Bologna, Bologna, Italy
| | - Serena Silvi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy
- Dipartimento di Chimica 'G. Ciamician', Università di Bologna, Bologna, Italy
| | - Emanuele Penocchio
- Department of Physics and Materials Science, University of Luxembourg, Luxembourg City, Luxembourg
| | - Massimiliano Esposito
- Department of Physics and Materials Science, University of Luxembourg, Luxembourg City, Luxembourg
| | - Alberto Credi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNR, Bologna, Italy.
- Dipartimento di Chimica Industriale 'Toso Montanari', Università di Bologna, Bologna, Italy.
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18
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Substrate Photoswitching for Rate Enhancement of an Organocatalytic Cyclization Reaction. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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19
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Ben-Tal Y, Boaler PJ, Dale HJA, Dooley RE, Fohn NA, Gao Y, García-Domínguez A, Grant KM, Hall AMR, Hayes HLD, Kucharski MM, Wei R, Lloyd-Jones GC. Mechanistic analysis by NMR spectroscopy: A users guide. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 129:28-106. [PMID: 35292133 DOI: 10.1016/j.pnmrs.2022.01.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 06/14/2023]
Abstract
A 'principles and practice' tutorial-style review of the application of solution-phase NMR in the analysis of the mechanisms of homogeneous organic and organometallic reactions and processes. This review of 345 references summarises why solution-phase NMR spectroscopy is uniquely effective in such studies, allowing non-destructive, quantitative analysis of a wide range of nuclei common to organic and organometallic reactions, providing exquisite structural detail, and using instrumentation that is routinely available in most chemistry research facilities. The review is in two parts. The first comprises an introduction to general techniques and equipment, and guidelines for their selection and application. Topics include practical aspects of the reaction itself, reaction monitoring techniques, NMR data acquisition and processing, analysis of temporal concentration data, NMR titrations, DOSY, and the use of isotopes. The second part comprises a series of 15 Case Studies, each selected to illustrate specific techniques and approaches discussed in the first part, including in situ NMR (1/2H, 10/11B, 13C, 15N, 19F, 29Si, 31P), kinetic and equilibrium isotope effects, isotope entrainment, isotope shifts, isotopes at natural abundance, scalar coupling, kinetic analysis (VTNA, RPKA, simulation, steady-state), stopped-flow NMR, flow NMR, rapid injection NMR, pure shift NMR, dynamic nuclear polarisation, 1H/19F DOSY NMR, and in situ illumination NMR.
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Affiliation(s)
- Yael Ben-Tal
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Patrick J Boaler
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Harvey J A Dale
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Ruth E Dooley
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom; Evotec (UK) Ltd, 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire OX14 4RZ, United Kingdom
| | - Nicole A Fohn
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Yuan Gao
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Andrés García-Domínguez
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Katie M Grant
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Andrew M R Hall
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Hannah L D Hayes
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Maciej M Kucharski
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Ran Wei
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Guy C Lloyd-Jones
- School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom.
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20
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Gansmüller A, Mikhailov AA, Kostin GA, Raya J, Palin C, Woike T, Schaniel D. Solid-State Photo-NMR Study on Light-Induced Nitrosyl Linkage Isomers Uncovers Their Structural, Electronic, and Diamagnetic Nature. Anal Chem 2022; 94:4474-4483. [PMID: 35229596 DOI: 10.1021/acs.analchem.1c05564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A light-induced linkage NO isomer (MS1) in trans-[Ru(15NO)(py)419F](ClO4)2 is detected and measured for the first time by solid-state MAS NMR. Chemical shift tensors of 15N and 19F, along with nJ(15N-19F) spin-spin couplings and T1 relaxation times of MS1, are compared with the ground state (GS) at temperatures T < 250 K. Isotropic chemical shifts (15N and 19F) are well resolved for two crystallographically independent cations (A and B) [Ru(15NO)(py)419F]2+, allowing to define separately both populations of MS1 isomers and thermal decay rates for two structural sites. The relaxation times T1 of 19F in the case of GS (30/38.6 s for sites A/B) and MS1 (11.6/11.8 s for sites A/B) indicate that both isomers are diamagnetic, which is the first experimental evidence of diamagnetic properties of MS1 in ruthenium nitrosyl. After light irradiation (λ = 420 nm), the NO ligand rotates by nearly 180° from F-Ru-N-O to F-Ru-O-N, whereby the isotropic chemical shifts of δiso(15N) increase and those of δiso(19F) decrease. The nJ(15N-19F) couplings increase from 2J(15N-Ru-19F)GS = 71 Hz to 3J(15N-O-Ru-19F)MS1 = 105 Hz. These results are interpreted on the basis of DFT-CASTEP calculations including Bader-, Mulliken-, and Hirshfeld-charge density distributions of both states.
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Affiliation(s)
| | - Artem A Mikhailov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 Acad. Lavrentiev Avenue, 630090, Novosibirsk, Russian Federation
| | - Gennadiy A Kostin
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 Acad. Lavrentiev Avenue, 630090, Novosibirsk, Russian Federation
| | - Jésus Raya
- Institut de Chimie de Strasbourg, UMR 7177 CNRS-Université de Strasbourg, 67000 Strasbourg, France
| | - Cyril Palin
- Université de Lorraine, CNRS, CRM2, F-54000 Nancy, France
| | - Theo Woike
- Université de Lorraine, CNRS, CRM2, F-54000 Nancy, France
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21
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Fillbrook LL, Nothling MD, Stenzel MH, Price WS, Beves JE. Rapid Online Analysis of Photopolymerization Kinetics and Molecular Weight Using Diffusion NMR. ACS Macro Lett 2022; 11:166-172. [PMID: 35574764 DOI: 10.1021/acsmacrolett.1c00719] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Online, high-throughput molecular weight analysis of polymerizations is rare, with most studies relying on tedious sampling techniques and batchwise postanalysis. The ability to track both monomer conversion and molecular weight evolution in real time could underpin precision polymer development and facilitate study of rapid polymerization reactions. Here, we use a single time-resolved diffusion nuclear magnetic resonance (NMR) experiment to simultaneously study the kinetics and molecular weight evolution during a photopolymerization, with in situ irradiation inside the NMR instrument. As a model system, we used a photoinduced electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The data allow diffusion coefficients and intensities to be calculated every 14 s from which the polymer size and monomer conversion can be extracted. Key to this approach is (1) the use of shuffled gradient amplitudes in the diffusion NMR experiment to access reactions of any rate, (2) the addition of a relaxation agent to increase achievable time resolution and, (3) a sliding correction that accounts for viscosity changes during polymerization. Diffusion NMR offers a uniquely simple, translatable handle for online monitoring of polymerization reactions.
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Affiliation(s)
| | | | | | - William S. Price
- Nanoscale Group, School of Science, Western Sydney University, Penrith, NSW 2751, Australia
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22
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Tay NES, Lehnherr D, Rovis T. Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis. Chem Rev 2022; 122:2487-2649. [PMID: 34751568 PMCID: PMC10021920 DOI: 10.1021/acs.chemrev.1c00384] [Citation(s) in RCA: 110] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do electrochemistry and photoredox catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) that enable bond formations not constrained by the rules of ionic or 2 electron (e) mechanisms. Instead, they enable 1e mechanisms capable of bypassing electronic or steric limitations and protecting group requirements, thus enabling synthetic chemists to disconnect molecules in new and different ways. However, while providing access to similar intermediates, electrochemistry and photoredox catalysis differ in several physical chemistry principles. Understanding those differences can be key to designing new transformations and forging new bond disconnections. This review aims to highlight these differences and similarities between electrochemistry and photoredox catalysis by comparing their underlying physical chemistry principles and describing their impact on electrochemical and photochemical methods.
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Affiliation(s)
- Nicholas E S Tay
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dan Lehnherr
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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23
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Wilcken R, Gerwien A, Huber LA, Dube H, Riedle E. Quantitative
In‐Situ
NMR Illumination for Excitation and Kinetic Analysis of Molecular Motor Intermediates. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202100232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Roland Wilcken
- Lehrstuhl für BioMolekulare Optik Ludwig-Maximilians-Universität München Oettingenstr. 67 80538 München Germany
- Chair of Organic Chemistry I Friedrich-Alexander-Universität Erlangen-Nürnberg Department of Chemistry and Pharmacy Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
| | - Aaron Gerwien
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 (Haus F) 81377 München Germany
| | - Ludwig Alexander Huber
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 (Haus F) 81377 München Germany
| | - Henry Dube
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 (Haus F) 81377 München Germany
- Chair of Organic Chemistry I Friedrich-Alexander-Universität Erlangen-Nürnberg Department of Chemistry and Pharmacy Nikolaus-Fiebiger-Str. 10 91058 Erlangen Germany
| | - Eberhard Riedle
- Lehrstuhl für BioMolekulare Optik Ludwig-Maximilians-Universität München Oettingenstr. 67 80538 München Germany
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24
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Adams RW, John RO, Blazina D, Eguillor B, Cockett MCR, Dunne JP, López‐Serrano J, Duckett SB. Contrasting Photochemical and Thermal Catalysis by Ruthenium Arsine Complexes Revealed by Parahydrogen Enhanced NMR Spectroscopy. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202100991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ralph W. Adams
- Department of Chemistry University of York Heslington, York YO10 5DD UK
- Current address: School of Chemistry University of Manchester Manchester M13 9PL UK
| | - Richard O. John
- Department of Chemistry University of York Heslington, York YO10 5DD UK
- Current address: Department of Physics University of York Heslington, York YO10 5DD UK
| | - Damir Blazina
- Department of Chemistry University of York Heslington, York YO10 5DD UK
| | - Beatriz Eguillor
- Department of Chemistry University of York Heslington, York YO10 5DD UK
- Current address: Departamento de Química Inorgánica Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) Centro de Innovación en Química Avanzada (ORFEO-CINQA) Universidad de Zaragoza – CSIC 50009 Zaragoza Spain
| | | | - John P. Dunne
- Department of Chemistry University of York Heslington, York YO10 5DD UK
| | - Joaquín López‐Serrano
- Department of Chemistry University of York Heslington, York YO10 5DD UK
- Current address: Departmento de Química Inorgánica Universidad de Sevilla 41012 Sevilla, Andalucía Spain
| | - Simon B. Duckett
- Department of Chemistry University of York Heslington, York YO10 5DD UK
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25
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Pietrzak M, Buczyńska J, Duus F, Waluk J, Hansen PE. Photoinduced and ground state conversions in a cyclic β-thioxoketone. RSC Adv 2021; 12:681-689. [PMID: 35425142 PMCID: PMC8697321 DOI: 10.1039/d1ra09020h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 12/16/2021] [Indexed: 12/30/2022] Open
Abstract
The photochemistry of a cyclic β-thioxoketone (2-methyl-1-(2-thioxycyclohexyl)propan-1-one (MTPO)) is investigated by NMR, UV, and IR experiments supported by DFT calculations. MTPO exists as a tautomeric mixture of an enol and a thiol form. Irradiation at low temperature led to a cis–trans isomerization of the thiol form resulting in a rather unusual enethiol (3). This is followed by a transfer of the isopropyl methine proton onto the carbonyl carbon resulting in yet another enethiol isomer (4). The photoconversion mechanisms without water present are discussed. Photochemical experiments at ambient temperature showed involvement of water in the excited state and resulted in another keto-form (5). The same species was also obtained when the products of the low temperature experiments were kept in the dark at ambient temperature. The photochemistry of a cyclic β-thioxoketone (2-methyl-1-(2-thioxycyclohexyl)propan-1-one (MTPO)) is investigated by NMR, UV, and IR experiments supported by DFT calculations.![]()
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Affiliation(s)
- Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44 01-224 Warsaw Poland
| | - Joanna Buczyńska
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44 01-224 Warsaw Poland
| | - Fritz Duus
- Department of Science and Environment, Roskilde University Denmark
| | - Jacek Waluk
- Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44 01-224 Warsaw Poland .,Faculty of Mathematics and Science, Cardinal Stefan Wyszyński University Dewajtis 5 01-815 Warsaw Poland
| | - Poul Erik Hansen
- Department of Science and Environment, Roskilde University Denmark
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26
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Pietrzak M, Jopa S, Mames A, Urbańczyk M, Woźny M, Ratajczyk T. Recent Progress in Liquid State Electrochemistry Coupled with NMR Spectroscopy. ChemElectroChem 2021. [DOI: 10.1002/celc.202100724] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Mariusz Pietrzak
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
| | - Sylwia Jopa
- Faculty of Chemistry University of Warsaw Pasteura 1 02-093 Warsaw Poland
| | - Adam Mames
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
| | - Mateusz Urbańczyk
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
- Centre of New Technologies University of Warsaw Banacha 2 C 02-097 Warsaw Poland
| | - Mateusz Woźny
- Institute of Organic Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
| | - Tomasz Ratajczyk
- Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warsaw Poland
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27
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Kristinaityte K, Urbańczyk M, Mames A, Pietrzak M, Ratajczyk T. Photoreactivity of an Exemplary Anthracene Mixture Revealed by NMR Studies, including a Kinetic Approach. Molecules 2021; 26:6695. [PMID: 34771104 PMCID: PMC8587725 DOI: 10.3390/molecules26216695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022] Open
Abstract
Anthracenes are an important class of acenes. They are being utilized more and more often in chemistry and materials sciences, due to their unique rigid molecular structure and photoreactivity. In particular, photodimerization can be harnessed for the fabrication of novel photoresponsive materials. Photodimerization between the same anthracenes have been investigated and utilized in various fields, while reactions between varying anthracenes have barely been investigated. Here, Nuclear Magnetic Resonance (NMR) spectroscopy is employed for the investigation of the photodimerization of two exemplary anthracenes: anthracene (A) and 9-bromoanthracene (B), in the solutions with only A or B, and in the mixture of A and B. Estimated k values, derived from the presented kinetic model, showed that the dimerization of A was 10 times faster in comparison with B when compounds were investigated in separate samples, and 2 times faster when compounds were prepared in the mixture. Notably, the photoreaction in the mixture, apart from AA and BB, additionally yielded a large amount of the AB mixdimer. Another important advantage of investigating a mixture with different anthracenes is the ability to estimate the relative reactivity for all the reactions under the same experimental conditions. This results in a better understanding of the photodimerization processes. Thus, the rational photofabrication of mix-anthracene-based materials can be facilitated, which is of crucial importance in the field of polymer and material sciences.
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Affiliation(s)
| | | | | | - Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Sciences, PL-01224 Warsaw, Poland; (K.K.); (M.U.); (A.M.)
| | - Tomasz Ratajczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, PL-01224 Warsaw, Poland; (K.K.); (M.U.); (A.M.)
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28
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Optical Fibre-Enabled Photoswitching for Localised Activation of an Anti-Cancer Therapeutic Drug. Int J Mol Sci 2021; 22:ijms221910844. [PMID: 34639185 PMCID: PMC8509559 DOI: 10.3390/ijms221910844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 11/17/2022] Open
Abstract
Local activation of an anti-cancer drug when and where needed can improve selectivity and reduce undesirable side effects. Photoswitchable drugs can be selectively switched between active and inactive states by illumination with light; however, the clinical development of these drugs has been restricted by the difficulty in delivering light deep into tissue where needed. Optical fibres have great potential for light delivery in vivo, but their use in facilitating photoswitching in anti-cancer compounds has not yet been explored. In this paper, a photoswitchable chemotherapeutic is switched using an optical fibre, and the cytotoxicity of each state is measured against HCT-116 colorectal cancer cells. The performance of optical-fibre-enabled photoswitching is characterised through its dose response. The UV–Vis spectra confirm light delivered by an optical fibre effectively enables photoswitching. The activated drug is shown to be twice as effective as the inactive drug in causing cancer cell death, characterised using an MTT assay and fluorescent microscopy. This is the first study in which a photoswitchable anti-cancer compound is switched using an optical fibre and demonstrates the feasibility of using optical fibres to activate photoswitchable drugs for potential future clinical applications.
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Fiedorowicz M, Wieteska M, Rylewicz K, Kossowski B, Piątkowska-Janko E, Czarnecka AM, Toczylowska B, Bogorodzki P. Hyperpolarized 13C tracers: Technical advancements and perspectives for clinical applications. Biocybern Biomed Eng 2021. [DOI: 10.1016/j.bbe.2021.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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30
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Ji Y, Bottecchia C, Lévesque F, Narsimhan K, Lehnherr D, McMullen JP, Dalby SM, Xiao KJ, Reibarkh M. Benzylic Photobromination for the Synthesis of Belzutifan: Elucidation of Reaction Mechanisms Using In Situ LED-NMR. J Org Chem 2021; 87:2055-2062. [PMID: 34590859 DOI: 10.1021/acs.joc.1c01465] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A detailed mechanistic understanding of a benzylic photobromination en route to belzutifan (MK-6482, a small molecule for the treatment of renal cell carcinoma associated with von Hippel-Lindau syndrome) has been achieved using in situ LED-NMR spectroscopy in conjunction with kinetic analysis. Two distinct mechanisms of overbromination, namely, the ionic and radical pathways, have been revealed by this study. The behavior of the major reaction species, including reactants, intermediates, products, and side products, has been elucidated. Comprehensive understanding of both pathways informed and enabled mitigation of a major process risk: a sudden product decomposition. Detailed knowledge of the processes occurring during the reaction and their potential liabilities enabled the development of a robust photochemical continuous flow process implemented for commercial manufacturing.
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Affiliation(s)
- Yining Ji
- Analytical Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Cecilia Bottecchia
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - François Lévesque
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Karthik Narsimhan
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Dan Lehnherr
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Jonathan P McMullen
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Stephen M Dalby
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Kai-Jiong Xiao
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Mikhail Reibarkh
- Analytical Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
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31
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Corra S, Casimiro L, Baroncini M, Groppi J, La Rosa M, Tranfić Bakić M, Silvi S, Credi A. Artificial Supramolecular Pumps Powered by Light. Chemistry 2021; 27:11076-11083. [PMID: 33951231 PMCID: PMC8453702 DOI: 10.1002/chem.202101163] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Indexed: 12/13/2022]
Abstract
The development of artificial nanoscale motors that can use energy from a source to perform tasks requires systems capable of performing directionally controlled molecular movements and operating away from chemical equilibrium. Here, the design, synthesis and properties of pseudorotaxanes are described, in which a photon input triggers the unidirectional motion of a macrocyclic ring with respect to a non-symmetric molecular axle. The photoinduced energy ratcheting at the basis of the pumping mechanism is validated by measuring the relevant thermodynamic and kinetic parameters. Owing to the photochemical behavior of the azobenzene moiety embedded in the axle, the pump can repeat its operation cycle autonomously under continuous illumination. NMR spectroscopy was used to observe the dissipative non-equilibrium state generated in situ by light irradiation. We also show that fine changes in the axle structure lead to an improvement in the performance of the motor. Such results highlight the modularity and versatility of this minimalist pump design, which provides facile access to dynamic systems that operate under photoinduced non-equilibrium regimes.
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Affiliation(s)
- Stefano Corra
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Chimica Industriale “Toso Montanari”Università di BolognaViale del Risorgimento 440136BolognaItaly
| | - Lorenzo Casimiro
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Chimica “G. Ciamician”Università di BolognaVia Selmi 240126BolognaItaly
- Université Paris-Saclay, CNRS, PPSM4 Avenue des Sciences91190Gif-sur-YvetteFrance
| | - Massimo Baroncini
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Scienze e Tecnologie Agro-alimentariUniversità di BolognaViale Fanin 4440127BolognaItaly
| | - Jessica Groppi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
| | - Marcello La Rosa
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Scienze e Tecnologie Agro-alimentariUniversità di BolognaViale Fanin 4440127BolognaItaly
| | - Marina Tranfić Bakić
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Chimica Industriale “Toso Montanari”Università di BolognaViale del Risorgimento 440136BolognaItaly
| | - Serena Silvi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Chimica “G. Ciamician”Università di BolognaVia Selmi 240126BolognaItaly
| | - Alberto Credi
- CLAN-Center for Light Activated Nanostructures, Istituto ISOF-CNRVia Gobetti 10140129BolognaItaly
- Dipartimento di Chimica Industriale “Toso Montanari”Università di BolognaViale del Risorgimento 440136BolognaItaly
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Gomez MV, Ruiz-Castañeda M, Nitschke P, Gschwind RM, Jiménez MA. Insights Into the Micelle-Induced β-Hairpin-to-α-Helix Transition of a LytA-Derived Peptide by Photo-CIDNP Spectroscopy. Int J Mol Sci 2021; 22:ijms22136666. [PMID: 34206372 PMCID: PMC8268221 DOI: 10.3390/ijms22136666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/07/2021] [Accepted: 06/16/2021] [Indexed: 11/16/2022] Open
Abstract
A choline-binding module from pneumococcal LytA autolysin, LytA239–252, was reported to have a highly stable nativelike β-hairpin in aqueous solution, which turns into a stable amphipathic α-helix in the presence of micelles. Here, we aim to obtain insights into this DPC-micelle triggered β-hairpin-to-α-helix conformational transition using photo-CIDNP NMR experiments. Our results illustrate the dependency between photo-CIDNP phenomena and the light intensity in the sample volume, showing that the use of smaller-diameter (2.5 mm) NMR tubes instead of the conventional 5 mm ones enables more efficient illumination for our laser-diode light setup. Photo-CIDNP experiments reveal different solvent accessibility for the two tyrosine residues, Y249 and Y250, the latter being less accessible to the solvent. The cross-polarization effects of these two tyrosine residues of LytA239–252 allow for deeper insights and evidence their different behavior, showing that the Y250 aromatic side chain is involved in a stronger interaction with DPC micelles than Y249 is. These results can be interpreted in terms of the DPC micelle disrupting the aromatic stacking between W241 and Y250 present in the nativelike β-hairpin, hence initiating conversion towards the α-helix structure. Our photo-CIDNP methodology represents a powerful tool for observing residue-level information in switch peptides that is difficult to obtain by other spectroscopic techniques.
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Affiliation(s)
- M. Victoria Gomez
- IRICA, Department of Inorganic, Organic and Biochemistry, Faculty of Chemical Sciences and Technologies, Universidad de Castilla-La Mancha (UCLM), Av. Camilo José Cela 10, 13071 Ciudad Real, Spain;
- Correspondence: (M.V.G.); (M.A.J.)
| | - Margarita Ruiz-Castañeda
- IRICA, Department of Inorganic, Organic and Biochemistry, Faculty of Chemical Sciences and Technologies, Universidad de Castilla-La Mancha (UCLM), Av. Camilo José Cela 10, 13071 Ciudad Real, Spain;
| | - Philipp Nitschke
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany; (P.N.); (R.M.G.)
| | - Ruth M. Gschwind
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany; (P.N.); (R.M.G.)
| | - M. Angeles Jiménez
- Departamento de Química-Física Biológica, Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain
- Correspondence: (M.V.G.); (M.A.J.)
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33
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Paululat T, Rabe M, Berdnikova DV. Modification of an NMR probe for monitoring of photoreactions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 327:106990. [PMID: 33932912 DOI: 10.1016/j.jmr.2021.106990] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
We describe a modified NMR probe for the in situ irradiation studies of photochemical reactions in solution-state NMR. To build up this setup, we designed an irradiation insert that brings eight light-emitting diodes (LEDs) into the NMR probe in the immediate proximity of the sample. The inserts with LEDs of different wavelengths are easily exchangeable within minutes. A tunable power supply allows to adjust the light intensity to optimize the irradiation conditions.
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Affiliation(s)
- Thomas Paululat
- Dr. Daria V. Berdnikova, Universität Siegen, Organische Chemie II, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
| | - Markus Rabe
- Universität Siegen, Werkstatt AR, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
| | - Daria V Berdnikova
- Dr. Daria V. Berdnikova, Universität Siegen, Organische Chemie II, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
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34
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Jabeen S, Farag M, Malek B, Choudhury R, Greer A. A Singlet Oxygen Priming Mechanism: Disentangling of Photooxidative and Downstream Dark Effects. J Org Chem 2020; 85:12505-12513. [PMID: 32885660 DOI: 10.1021/acs.joc.0c01712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Airborne singlet oxygen obtained from photosensitization of triplet dioxygen is shown to react with an alkene surfactant (8-methylnon-7-ene-1 sulfonate) leading to "ene" hydroperoxides that in the dark inactivate planktonic Escherichia coli (E. coli). The "ene" hydroperoxide photoproducts are not toxic on their own, but they become toxic after the bacteria are pretreated with singlet oxygen. The total quenching rate constant (kT) of singlet oxygen of the alkene surfactant was measured to be 1.1 × 106 M-1 s-1 at the air/liquid interface. Through a new mechanism called singlet oxygen priming (SOP), the singlet oxygen leads to hydroperoxides then to peroxyl radicals, tetraoxides, and decomposition products, which also promote disinfection, and therefore offer a "one-two" punch. This offers a strong secondary toxic effect in an otherwise indiscernible dark reaction. The results provide an insight into assisted killing by an exogenous alkene with dark toxicity effects following exposure to singlet oxygen.
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Affiliation(s)
- Shakeela Jabeen
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Maria Farag
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States
| | - Belaid Malek
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States
| | - Rajib Choudhury
- Department of Chemistry, Arkansas Tech University, Russellville, Arkansas 72801, United States
| | - Alexander Greer
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, New York 11210, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
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35
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Yakubov S, Barham JP. Photosensitized direct C-H fluorination and trifluoromethylation in organic synthesis. Beilstein J Org Chem 2020; 16:2151-2192. [PMID: 32952732 PMCID: PMC7476599 DOI: 10.3762/bjoc.16.183] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022] Open
Abstract
The importance of fluorinated products in pharmaceutical and medicinal chemistry has necessitated the development of synthetic fluorination methods, of which direct C-H fluorination is among the most powerful. Despite the challenges and limitations associated with the direct fluorination of unactivated C-H bonds, appreciable advancements in manipulating the selectivity and reactivity have been made, especially via transition metal catalysis and photochemistry. Where transition metal catalysis provides one strategy for C-H bond activation, transition-metal-free photochemical C-H fluorination can provide a complementary selectivity via a radical mechanism that proceeds under milder conditions than thermal radical activation methods. One exciting development in C-F bond formation is the use of small-molecule photosensitizers, allowing the reactions i) to proceed under mild conditions, ii) to be user-friendly, iii) to be cost-effective and iv) to be more amenable to scalability than typical photoredox-catalyzed methods. In this review, we highlight photosensitized C-H fluorination as a recent strategy for the direct and remote activation of C-H (especially C(sp3)-H) bonds. To guide the readers, we present the developing mechanistic understandings of these reactions and exemplify concepts to assist the future planning of reactions.
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Affiliation(s)
- Shahboz Yakubov
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
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36
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Skubi KL, Swords WB, Hofstetter H, Yoon TP. LED-NMR Monitoring of an Enantioselective Catalytic [2+2] Photocycloaddition. CHEMPHOTOCHEM 2020; 4:685-690. [PMID: 34532566 PMCID: PMC8443221 DOI: 10.1002/cptc.202000094] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Indexed: 01/08/2023]
Abstract
We report that an NMR spectrometer equipped with a high-power LED light source can be used to study a fast enantioselective photocatalytic [2+2] cycloaddition. While traditional ex situ applications of NMR provide considerable information on reaction mechanisms, they are often ineffective for observing fast reactions. Recently, motivated by renewed interest in organic photochemistry, several approaches have been reported for in situ monitoring of photochemical reactions. These previously disclosed methods, however, have rarely been applied to rapid (<5 min) photochemical reactions. Furthermore, these approaches have not previously been used to interrogate the mechanisms of photocatalytic energy-transfer reactions. In the present work, we describe our experimental setup and demonstrate its utility by determining a phenomenological rate law for a model photocatalytic energy-transfer cycloaddition reaction.
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Affiliation(s)
- Kazimer L Skubi
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI (USA)
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY (USA)
| | - Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI (USA)
| | - Heike Hofstetter
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI (USA)
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI (USA)
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37
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Berton C, Busiello DM, Zamuner S, Solari E, Scopelliti R, Fadaei-Tirani F, Severin K, Pezzato C. Thermodynamics and kinetics of protonated merocyanine photoacids in water. Chem Sci 2020; 11:8457-8468. [PMID: 34123105 PMCID: PMC8163397 DOI: 10.1039/d0sc03152f] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 07/27/2020] [Indexed: 12/19/2022] Open
Abstract
Metastable-state photoacids (mPAHs) are chemical species whose photo-activated state is long-lived enough to allow for proton diffusion. Liao's photoacid (1) represents the archetype of mPAHs, and is being widely used on account of its unique capability to change the acidity of aqueous solutions reversibly. The behavior of 1 in water, however, still remains poorly understood. Herein, we provide in-depth insights on the thermodynamics and kinetics of 1 in water through a series of comparative 1H NMR and UV-Vis studies and relative modelling. Under dark conditions, we quantified a three-component equilibrium system where the dissociation (K a) of the open protonated form (MCH) is followed by isomerization (K c) of the open deprotonated form (MC) to the closed spiropyran form (SP) - i.e., in the absence of light, the ground state acidity can be expressed as K GS a = K a(1 + K c). On the other hand, under powerful and continuous light irradiation we were able to assess, for the first time experimentally, the dissociation constant (K MS a) of the protonated metastable state (cis-MCH). In addition, we found that thermal ring-opening of SP is always rate-determining regardless of pH, whereas hydrolysis is reminiscent of what is found for Schiff bases. The proposed methodology is general, and it was applied to two other compounds bearing a shorter (ethyl, 2) and a longer (butyl, 3) alkyl-1-sulfonate bridge. We found that the pK a remains constant, whereas both pK c and pK MS a linearly increase with the length of the alkyl bridge. Importantly, all results are consistent with a four-component model cycle, which describes perfectly the full dynamics of proton release/uptake of 1-3 in water. The superior hydrolytic stability and water solubility of compound 3, together with its relatively high pK GS a (low K c), allowed us to achieve fully reversible jumps of 2.5 pH units over 18 consecutive cycles (6 hours).
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Affiliation(s)
- Cesare Berton
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Daniel Maria Busiello
- Institut de Physique, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Stefano Zamuner
- Institut de Physique, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Euro Solari
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Rosario Scopelliti
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Farzaneh Fadaei-Tirani
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Kay Severin
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Cristian Pezzato
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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38
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Barham JP, König B. Synthetic Photoelectrochemistry. Angew Chem Int Ed Engl 2020; 59:11732-11747. [PMID: 31805216 PMCID: PMC7383880 DOI: 10.1002/anie.201913767] [Citation(s) in RCA: 173] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/03/2019] [Indexed: 01/06/2023]
Abstract
Photoredox catalysis (PRC) and synthetic organic electrochemistry (SOE) are often considered competing technologies in organic synthesis. Their fusion has been largely overlooked. We review state-of-the-art synthetic organic photoelectrochemistry, grouping examples into three categories: 1) electrochemically mediated photoredox catalysis (e-PRC), 2) decoupled photoelectrochemistry (dPEC), and 3) interfacial photoelectrochemistry (iPEC). Such synergies prove beneficial not only for synthetic "greenness" and chemical selectivity, but also in the accumulation of energy for accessing super-oxidizing or -reducing single electron transfer (SET) agents. Opportunities and challenges in this emerging and exciting field are discussed.
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Affiliation(s)
- Joshua P. Barham
- Universität RegensburgFakultät für Chemie und Pharmazie93040RegensburgGermany
| | - Burkhard König
- Universität RegensburgFakultät für Chemie und Pharmazie93040RegensburgGermany
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39
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Affiliation(s)
- Joshua P. Barham
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
| | - Burkhard König
- Universität Regensburg Fakultät für Chemie und Pharmazie 93040 Regensburg Deutschland
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40
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Niedek D, Erb FR, Topp C, Seitz A, Wende RC, Eckhardt AK, Kind J, Herold D, Thiele CM, Schreiner PR. In Situ Switching of Site-Selectivity with Light in the Acetylation of Sugars with Azopeptide Catalysts. J Org Chem 2020; 85:1835-1846. [PMID: 31763833 DOI: 10.1021/acs.joc.9b01913] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present a novel concept for the in situ control of site-selectivity of catalytic acetylations of partially protected sugars using light as external stimulus and oligopeptide catalysts equipped with an azobenzene moiety. The isomerizable azobenzene-peptide backbone defines the size and shape of the catalytic pocket, while the π-methyl-l-histidine (Pmh) moiety transfers the electrophile. Photoisomerization of the E- to the Z-azobenzene catalyst (monitored via NMR) with an LED (λ = 365 nm) drastically changes the chemical environment around the catalytically active Pmh moiety, so that the light-induced change in the catalyst shape alters site-selectivity. As a proof of principle, we employed (4,6-O-benzylidene)methyl-α-d-pyranosides, which provide a change in regioselectivity from 2:1 (E) to 1:5 (Z) for the monoacetylated products at room temperature. The validity of this new catalyst-design concept is further demonstrated with the regioselective acetylation of the natural product quercetin. In situ irradiation NMR spectroscopy was used to quantify photostationary states under continuous irradiation with UV light.
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Affiliation(s)
- Dominik Niedek
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Frederik R Erb
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Christopher Topp
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Alexander Seitz
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Raffael C Wende
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - André K Eckhardt
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Jonas Kind
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 16 , 64287 Darmstadt , Germany
| | - Dominik Herold
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 16 , 64287 Darmstadt , Germany
| | - Christina M Thiele
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 16 , 64287 Darmstadt , Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
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41
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Kennedy ADW, Sandler I, Andréasson J, Ho J, Beves JE. Visible‐Light Photoswitching by Azobenzazoles. Chemistry 2020; 26:1103-1110. [DOI: 10.1002/chem.201904309] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Indexed: 11/09/2022]
Affiliation(s)
| | - Isolde Sandler
- School of Chemistry UNSW Sydney Sydney NSW 2052 Australia
| | - Joakim Andréasson
- Department of Chemistry and Chemical Engineering Chalmers University of Technology 412 96 Göteborg Sweden
| | - Junming Ho
- School of Chemistry UNSW Sydney Sydney NSW 2052 Australia
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42
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Toncheva-Moncheva N, Dangalov M, Vassilev NG, Novakov CP. Thiol–ene coupling reaction achievement and monitoring by “ in situ” UV irradiation NMR spectroscopy. RSC Adv 2020; 10:25214-25222. [PMID: 35517473 PMCID: PMC9055274 DOI: 10.1039/d0ra03902k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/18/2020] [Indexed: 11/21/2022] Open
Abstract
In this study, the possibilities of a new “in situ” LED UV illumination NMR spectroscopic technique for performing an initiator-free thiol–ene “click” coupling reaction of an allyl-functionalized poly(allyl glycidyl ether) (PAGE) prepolymer with a number of mono- and di-oligo polyethylene glycol (PEG) thiols is demonstrated. The state-of-the-art setup constructed with LEDs as UV light sources that illuminate through optical fibers directly into an NMR testing tube at a fixed wavelength of 365 nm is appropriate for various polymeric materials and biologically active substances. The selected experimental protocol uses a series of periods of irradiation and dark periods, thus providing opportunities to conduct an effective thiol–ene “click” reaction and simultaneously study the kinetics of the photochemical reaction with the exposure time, as well as macromolecular association directly in a solution applying the whole types of NMR methods: from conventional 1H or 13C NMR to diffusion NMR spectroscopy (DOSY). In addition, the molecular mass characteristics of the prepared copolymers were studied by gel-permeation chromatography (GPC). The observed differences in the reaction rates as well as in the size of species formed (the corresponding hydrodynamic radiuses Rh of aggregates) as a result of the coupling process of parent PAGE prepolymers and model PEG thiols were thoroughly discussed and the reaction pathway proposed. An “In situ” LED UV illumination NMR setup for achievement of initiator-free coupling reactions of allyl-functionalized poly(allyl glycidyl ether) with polyethylene glycols thiols.![]()
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Affiliation(s)
| | - Miroslav Dangalov
- Institute of Organic Chemistry with Center of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
| | - Nikolay G. Vassilev
- Institute of Organic Chemistry with Center of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
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43
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Yang H, Hofstetter H, Cavagnero S. Fast-pulsing LED-enhanced NMR: A convenient and inexpensive approach to increase NMR sensitivity. J Chem Phys 2019; 151:245102. [PMID: 31893873 DOI: 10.1063/1.5131452] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) has recently emerged as a powerful technology for the detection of aromatic amino acids and proteins in solution in the low-micromolar to nanomolar concentration range. LC-photo-CIDNP is typically carried out in the presence of high-power lasers, which are costly and maintenance-heavy. Here, we show that LC-photo-CIDNP can be performed with light-emitting diodes (LEDs), which are inexpensive and much less cumbersome than lasers, laser diodes, flash lamps, or other light sources. When nuclear magnetic resonance (NMR) sample concentration is within the low-micromolar to nanomolar range, as in LC-photo-CIDNP, replacement of lasers with LEDs leads to no losses in sensitivity. We also investigate the effect of optical-fiber thickness and compare excitation rate constants of an Ar ion laser (488 nm) and a 466 nm LED, taking LED emission bandwidths into account. In addition, importantly, we develop a novel pulse sequence (13C RASPRINT) to perform ultrarapid LC-photo-CIDNP data collection. Remarkably, 13C RASPRINT leads to 4-fold savings in data collection time. The latter advance relies on the fact that photo-CID nuclear hyperpolarization does not suffer from the longitudinal-relaxation recovery requirements of conventional NMR. Finally, we combine both the above improvements, resulting in facile and rapid (≈16 s-2.5 min) collection of 1 and 2D NMR data on aromatic amino acids and proteins in solution at nanomolar to low micromolar concentration.
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Affiliation(s)
- Hanming Yang
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, USA
| | - Heike Hofstetter
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, USA
| | - Silvia Cavagnero
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, USA
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44
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Lokesh N, Hioe J, Gramüller J, Gschwind RM. Relaxation Dispersion NMR to Reveal Fast Dynamics in Brønsted Acid Catalysis: Influence of Sterics and H-Bond Strength on Conformations and Substrate Hopping. J Am Chem Soc 2019; 141:16398-16407. [PMID: 31545037 PMCID: PMC6863621 DOI: 10.1021/jacs.9b07841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Indexed: 12/25/2022]
Abstract
NMR provides both structural and dynamic information, which is key to connecting intermediates and to understanding reaction pathways. However, fast exchanging catalytic intermediates are often inaccessible by conventional NMR due its limited time resolution. Here, we show the combined application of the 1H off-resonance R1ρ NMR method and low temperature (185-175 K) to resolve intermediates exchanging on a μs time scale (ns at room temperature). The potential of the approach is demonstrated on chiral phosphoric acid (CPA) catalysts in their complexes with imines. The otherwise inaccessible exchange kinetics of the E-I ⇌ E-II imine conformations and thermodynamic E-I:E-II imine ratios inside the catalyst pocket are experimentally determined and corroborated by calculations. The E-I ⇌ E-II exchange rate constants (kex185 K) for different catalyst-substrate binary complexes varied between 2500 and 19 000 s-1 (τex = 500-50 μs). Theoretical analysis of these exchange rate constants revealed the involvement of an intermediary tilted conformation E-III, which structurally resembles the hydride transfer transition state. The main E-I and E-II exchange pathway is a hydrogen bond strength dependent tilting-switching-tilting mechanism via a bifurcated hydrogen bond as a transition state. The reduction in the sterics of the catalyst showed an accelerated switching process by at least an order of magnitude and enabled an additional rotational pathway. Hence, the exchange process is mainly a function of the intrinsic properties of the 3,3'-substituents of the catalyst. Overall, we believe that the present study opens a new dimension in catalysis via experimental access to structures, populations, and kinetics of catalyst-substrate complexes on the μs time scale by the 1H off-resonance R1ρ method.
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Affiliation(s)
- N. Lokesh
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Johnny Hioe
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Johannes Gramüller
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Ruth M. Gschwind
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
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