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Gorbachev V, Miloglyadova L, Chen P. An automatic variable laser power attenuator for continuous-wave quantum cascade lasers in cryogenic ion vibrational predissociation spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:093002. [PMID: 39240148 DOI: 10.1063/5.0189140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 08/13/2024] [Indexed: 09/07/2024]
Abstract
Cryogenic ion vibrational predissociation (CIVP) spectroscopy is an established and valuable technique for molecular elucidation in the gas phase. CIVP relies on tunable lasers, wherein among typical laser schemes, the application of mid-infrared continuous-wave quantum cascade laser (cw-QCL) is the most robust and elegant solution, as we have recently demonstrated. However, potential challenges arise from an inhomogeneous character across laser power tuning curves. A large laser power output could have undesired consequences, such as multiphoton absorption or saturation effects. Significant variations in laser power tuning curves could potentially alter the shape of the investigated band, particularly for diffuse bands. In this study, we have developed and introduced an automatic variable laser power attenuator designed to keep the laser power output uniform at a user-defined value across the entire available spectral range. We demonstrated the application of this attenuator in obtaining CIVP spectra of a model compound with a diffuse N-H-N band. This approach enhances the reliability of measuring diffuse bands and overall applicability of cw-QCL.
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Affiliation(s)
- Vladimir Gorbachev
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Larisa Miloglyadova
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Peter Chen
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
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2
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Tampellini N, Mercado BQ, Miller SJ. Scaffold-Oriented Asymmetric Catalysis: Conformational Modulation of Transition State Multivalency during a Catalyst-Controlled Assembly of a Pharmaceutically Relevant Atropisomer. Chemistry 2024; 30:e202401109. [PMID: 38507249 PMCID: PMC11132932 DOI: 10.1002/chem.202401109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 03/20/2024] [Indexed: 03/22/2024]
Abstract
A new class of superbasic, bifunctional peptidyl guanidine catalysts is presented, which enables the organocatalytic, atroposelective synthesis of axially chiral quinazolinediones. Computational modeling unveiled the conformational modulation of the catalyst by a novel phenyl urea N-cap, that preorganizes the structure into the active, folded state. A previously unanticipated noncovalent interaction involving a difluoroacetamide acting as a hybrid mono- or bidentate hydrogen bond donor emerged as a decisive control element inducing atroposelectivity. These discoveries spurred from a scaffold-oriented project inspired from a fascinating investigational BTK inhibitor featuring two stable chiral axes and relies on a mechanistic framework that was foreign to the extant lexicon of asymmetric catalysis.
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Affiliation(s)
- Nicolò Tampellini
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
| | - Scott J. Miller
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
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3
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Rummel L, Schreiner PR. Advances and Prospects in Understanding London Dispersion Interactions in Molecular Chemistry. Angew Chem Int Ed Engl 2024; 63:e202316364. [PMID: 38051426 DOI: 10.1002/anie.202316364] [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: 10/29/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/07/2023]
Abstract
London dispersion (LD) interactions are the main contribution of the attractive part of the van der Waals potential. Even though LD effects are the driving force for molecular aggregation and recognition, the role of these omnipresent interactions in structure and reactivity had been largely underappreciated over decades. However, in the recent years considerable efforts have been made to thoroughly study LD interactions and their potential as a chemical design element for structures and catalysis. This was made possible through a fruitful interplay of theory and experiment. This review highlights recent results and advances in utilizing LD interactions as a structural motif to understand and utilize intra- and intermolecularly LD-stabilized systems. Additionally, we focus on the quantification of LD interactions and their fundamental role in chemical reactions.
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Affiliation(s)
- Lars Rummel
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
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4
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Li H, Brémond E, Sancho-García JC, Pérez-Jiménez ÁJ, Scalmani G, Frisch MJ, Adamo C. Axial-equatorial equilibrium in substituted cyclohexanes: a DFT perspective on a small but complex problem. Phys Chem Chem Phys 2024; 26:8094-8105. [PMID: 38384253 DOI: 10.1039/d3cp06141h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
In Chemistry, complexity is not necessarily associated to large systems, as illustrated by the textbook example of axial-equatorial equilibrium in mono-substituted cyclohexanes. The difficulty in modelling such a simple isomerization is related to the need for reproducing the delicate balance between two forces, with opposite effects, namely the attractive London dispersion and the repulsive steric interactions. Such balance is a stimulating challenge for density-functional approximations and it is systematically explored here by considering 20 mono-substituted cyclohexanes. In comparison to highly accurate CCSD(T) reference calculations, their axial-equatorial equilibrium is studied with a large set of 48 exchange-correlation approximations, spanning from semilocal to hybrid to more recent double hybrid functionals. This dataset, called SAV20 (as Steric A-values for 20 molecules), allows to highlight the difficulties encountered by common and more original DFT approaches, including those corrected for dispersion with empirical potentials, the 6-31G*-ACP model, and our cost-effective PBE-QIDH/DH-SVPD protocol, in modeling these challenging interactions. Interestingly, the performance of the approaches considered in this contribution on the SAV20 dataset does not correlate with that obtained with other more standard datasets, such as S66, IDISP or NC15, thus indicating that SAV20 covers physicochemical features not already considered in previous noncovalent interaction benchmarks.
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Affiliation(s)
- Hanwei Li
- Chimie ParisTech, PSL Research University, CNRS, Institute of Chemistry for Health and Life Sciences, F-75005 Paris, France.
| | - Eric Brémond
- Université Paris Cité, ITODYS, CNRS, F-75006 Paris, France
| | | | | | | | | | - Carlo Adamo
- Chimie ParisTech, PSL Research University, CNRS, Institute of Chemistry for Health and Life Sciences, F-75005 Paris, France.
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5
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Yu J, Darú A, Deng M, Blackmond DG. Prebiotic access to enantioenriched amino acids via peptide-mediated transamination reactions. Proc Natl Acad Sci U S A 2024; 121:e2315447121. [PMID: 38315856 PMCID: PMC10873602 DOI: 10.1073/pnas.2315447121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/29/2023] [Indexed: 02/07/2024] Open
Abstract
The kinetic resolution of racemic amino acids mediated by dipeptides and pyridoxal provides a prebiotically plausible route to enantioenriched proteinogenic amino acids. The enzymatic transamination cycles that are key to modern biochemical formation of enantiopure amino acids may have evolved from this half of the reversible reaction couple. Kinetic resolution of racemic precursors emerges as a general route to enantioenrichment under prebiotic conditions.
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Affiliation(s)
- Jinhan Yu
- Department of Chemistry, Scripps Research, La Jolla, CA92037
| | - Andrea Darú
- Department of Chemistry, Scripps Research, La Jolla, CA92037
| | - Min Deng
- Department of Chemistry, Scripps Research, La Jolla, CA92037
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6
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Ma Z, Chen L, Xu C, Fournier JA. Two-Dimensional Infrared Spectroscopy of Isolated Molecular Ions. J Phys Chem Lett 2023; 14:9683-9689. [PMID: 37871134 DOI: 10.1021/acs.jpclett.3c02661] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Two-dimensional infrared (2D IR) spectroscopy of mass-selected, cryogenically cooled molecular ions is presented. Nonlinear response pathways, encoded in the time-domain photodissociation action response of weakly bound N2 messenger tags, were isolated using pulse shaping techniques following excitation with four collinear ultrafast IR pulses. 2D IR spectra of Re(CO)3(CH3CN)3+ ions capture off-diagonal cross-peak bleach signals between the asymmetric and symmetric carbonyl stretching transitions. These cross peaks display intensity variations as a function of pump-probe delay time due to coherent coupling between the vibrational modes. Well-resolved 2D IR features in the congested fingerprint region of protonated caffeine (C8H10N4O2H+) are also reported. Importantly, intense cross-peak signals were observed at 3 ps waiting time, indicating that tag-loss dynamics are not competing with the measured nonlinear signals. These demonstrations pave the way for more precise studies of molecular interactions and dynamics that are not easily obtainable with current condensed-phase methodologies.
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Affiliation(s)
- Zifan Ma
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Liangyi Chen
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Chuzhi Xu
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Joseph A Fournier
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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Foreman MM, Hirsch RJ, Weber JM. Influence of Metal Identity in Bipyridine-Based Metal-4N Complexes With Formate. J Phys Chem A 2023; 127:7586-7593. [PMID: 37647595 DOI: 10.1021/acs.jpca.3c04496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
We present the vibrational spectra of a series of dicationic, organometallic complexes consisting of a transition metal center (Co, Ni, or Cu) coordinated by 4,4'-di(tert-butyl)-2,2'-bipyridine (DTBbpy) ligands and a formate adduct. Spectral features are analyzed and assigned through comparison with density functional theory calculations, and structures are reported. Natural population analysis shows that the DTBbpy ligands serve as flexible charge reservoirs in each complex. Shifts in the vibrational signatures of the formate moiety reveal that the nature of the metal center plays a crucial role in the charge distribution and formate-metal binding motif in each complex, illustrating the impact of the metal center on the structural and electronic properties of these complexes.
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Affiliation(s)
- Madison M Foreman
- JILA and Department of Chemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309-0440, United States
| | - Rebecca J Hirsch
- JILA and Department of Chemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309-0440, United States
| | - J Mathias Weber
- JILA and Department of Chemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309-0440, United States
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8
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Tsybizova A, Fritsche L, Miloglyadova L, Kräutler B, Chen P. Cryogenic Ion Vibrational Predissociation (CIVP) Spectroscopy of Aryl Cobinamides in the Gas Phase: How Good Are the Calculations for Vitamin B 12 Derivatives? J Am Chem Soc 2023; 145:19561-19570. [PMID: 37656981 PMCID: PMC10510309 DOI: 10.1021/jacs.3c03001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Indexed: 09/03/2023]
Abstract
Aryl corrins represent a novel class of designed B12 derivatives with biological properties of "antivitamins B12". In our previous study, we experimentally determined bond strength in a series of aryl-corrins by the threshold collision-induced dissociation experiments (T-CID) and compared the measured bond dissociation energies (BDEs) with those calculated with density functional theory (DFT). We found that the BDEs are modulated by the side chains around the periphery of the corrin unit. Given that aryl cobinamides have many side chains that increase their conformational space and that the question of a specific structure, measured in the gas phase, was important for further evaluation of our T-CID experiment, we proceeded to analyze structural properties of aryl cobinamides using cryogenic ion vibrational predissociation (CIVP) spectroscopy, static DFT, and Born-Oppenheimer molecular dynamic (BOMD) simulations. We found that none of the examined DFT models could reproduce the CIVP spectra convincingly; both "static" DFT calculations and "dynamic" BOMD simulations provide a surprisingly poor representation of the vibrational spectra, specifically of the number, position, and intensity of bands assigned to hydrogen-bonded versus non-hydrogen-bonded NH and OH moieties. We conclude that, for a flexible molecule with ca. 150 atoms, more accurate approaches are needed before definitive conclusions about computed properties, specifically the structure of the ground-state conformer, may be made.
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Affiliation(s)
- Alexandra Tsybizova
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Lukas Fritsche
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Larisa Miloglyadova
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Bernhard Kräutler
- Institute
of Organic Chemistry, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Peter Chen
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
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9
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Watson ZL, Knudson IJ, Ward FR, Miller SJ, Cate JHD, Schepartz A, Abramyan AM. Atomistic simulations of the Escherichia coli ribosome provide selection criteria for translationally active substrates. Nat Chem 2023:10.1038/s41557-023-01226-w. [PMID: 37308707 DOI: 10.1038/s41557-023-01226-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 04/28/2023] [Indexed: 06/14/2023]
Abstract
As genetic code expansion advances beyond L-α-amino acids to backbone modifications and new polymerization chemistries, delineating what substrates the ribosome can accommodate remains a challenge. The Escherichia coli ribosome tolerates non-L-α-amino acids in vitro, but few structural insights that explain how are available, and the boundary conditions for efficient bond formation are so far unknown. Here we determine a high-resolution cryogenic electron microscopy structure of the E. coli ribosome containing α-amino acid monomers and use metadynamics simulations to define energy surface minima and understand incorporation efficiencies. Reactive monomers across diverse structural classes favour a conformational space where the aminoacyl-tRNA nucleophile is <4 Å from the peptidyl-tRNA carbonyl with a Bürgi-Dunitz angle of 76-115°. Monomers with free energy minima that fall outside this conformational space do not react efficiently. This insight should accelerate the in vivo and in vitro ribosomal synthesis of sequence-defined, non-peptide heterooligomers.
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Affiliation(s)
- Zoe L Watson
- Department of Chemistry, University of California, Berkeley, CA, USA
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
| | - Isaac J Knudson
- Department of Chemistry, University of California, Berkeley, CA, USA
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA
| | - Fred R Ward
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA, USA
| | - Scott J Miller
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA.
- Department of Chemistry, Yale University, New Haven, CT, USA.
| | - Jamie H D Cate
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA.
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA, USA.
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Alanna Schepartz
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Center for Genetically Encoded Materials, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA.
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA, USA.
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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10
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Rummel L, König HF, Hausmann H, Schreiner PR. Silyl Groups Are Strong Dispersion Energy Donors. J Org Chem 2022; 87:13168-13177. [PMID: 36166406 DOI: 10.1021/acs.joc.2c01633] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present an experimental and computational study to investigate noncovalent interactions between silyl groups that are often employed as "innocent" protecting groups. We chose an extended cyclooctatetraene (COT)-based molecular balance comprising unfolded (1,4-disubstituted) and folded (1,6-disubstituted) valance bond isomers that typically display remote and close silyl group contacts, respectively. The thermodynamic equilibria were determined using nuclear magnetic resonance measurements. Additionally, we utilized Boltzmann weighted symmetry-adapted perturbation theory (SAPT) at the sSAPT0/aug-cc-pVDZ level of theory to dissect and quantify noncovalent interactions. Apart from the extremely bulky tris(trimethylsilyl)silyl "supersilyl" group, there is a preference for the folded 1,6-COT valence isomer, with London dispersion interactions being the main stabilizing factor. This makes silyl groups excellent dispersion energy donors, a finding that needs to be taken into account in synthesis planning.
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Affiliation(s)
- Lars Rummel
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Henrik F König
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Heike Hausmann
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
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