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Puente AR, Polavarapu PL. Influence of microsolvation on vibrational circular dichroism spectra in dimethyl sulfoxide solvent: A Bottom-Up approach using Quantum cluster growth. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 303:123231. [PMID: 37562213 DOI: 10.1016/j.saa.2023.123231] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/09/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023]
Abstract
Chiroptical spectroscopic measurements serve as routine methods to assign the absolute configuration of chiral compounds and interpret their conformational behavior in solution. One common challenge is the use of strongly hydrogen-bonding solvents, which can significantly bias the conformational ensemble and affect the vibrational circular dichroism (VCD) active bands in solution. One such solvent is dimethyl sulfoxide (DMSO)-an excellent solvent for stubborn compounds-that must be explicitly considered in VCD analysis. Explicit consideration of solvent remains a critical challenge in chiroptical spectroscopy due to the need to explore solute-solvent conformational space and the computational expense in modeling these clusters. Interested in the recent development of the Quantum Cluster Growth (QCG) program by the Grimme lab, we set out to model and interpret previously reported VCD spectra for several molecules using their efficient program. Our purposes are two-fold: (1) to investigate the applicability of the QCG program to the problem of reproducing VCD spectra in DMSO solvent and (2) to identify limitations in using this approach. We find that we can conveniently model and analyze the VCD spectra of investigated molecules in DMSO. However, the final set of conformers used for VCD calculations are functional dependent and different sets of conformers can provide satisfactory quantitative agreement between experimental and predicted VCD spectra. We hope that this study provides guidance for future chiroptical studies in the challenging DMSO solvent.
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Affiliation(s)
- Andrew R Puente
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
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2
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Merten C. Modelling solute-solvent interactions in VCD spectra analysis with the micro-solvation approach. Phys Chem Chem Phys 2023; 25:29404-29414. [PMID: 37881890 DOI: 10.1039/d3cp03408a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Vibrational circular dichroism (VCD) spectroscopy has become an important part of the (stereo-)chemists' toolbox as a reliable method for the determination of absolute configurations. Being the chiroptical version of infrared spectroscopy, it has also been recognized as being very sensitive to conformational changes and intermolecular interactions. This sensitivity originates from the fact that the VCD spectra of individual conformers are often more different than their IR spectra, so that changes in conformational distributions or band positions and intensities become more pronounced. What is an advantage for studies focussing on intermolecular interactions can, however, quickly turn into a major obstacle during AC determinations: solute-solvent interactions can have a strong influence on spectral signatures and they must be accurately treated when simulating VCD and IR spectra. In this perspective, we showcase selected examples which exhibit particularly pronounced solvent effects. It is demonstrated that it is typically sufficient to model solute-solvent interactions by placing single solvent molecules near hydrogen bonding sites of the solute and subsequently use the optimized structures for spectra simulations. This micro-solvation approach works reasonably well for medium-sized, not too conformationally flexible molecules. We thus also discuss its limitations and outline the next steps that method development needs to take in order to further improve the workflows for VCD spectra predictions.
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Affiliation(s)
- Christian Merten
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
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3
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Jähnigen S. Vibrational Circular Dichroism Spectroscopy of Chiral Molecular Crystals: Insights from Theory. Angew Chem Int Ed Engl 2023; 62:e202303595. [PMID: 37071543 DOI: 10.1002/anie.202303595] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 04/19/2023]
Abstract
Chirality is a curious phenomenon that appears in various forms. While the concept of molecular (RS-)chirality is ubiquitous in chemistry, there are also more intricate forms of structural chirality. One of them is the enantiomorphism of crystals, especially molecular crystals, that describes the lack of mirror symmetry in the unit cell. Its relation to molecular chirality is not obvious, but still an open question, which can be addressed with chiroptical tools. Vibrational circular dichroism (VCD) denotes chiral infrared (IR) spectroscopy that is susceptible to both, the molecular as well as the intermolecular space by means of vibrational transitions. When carried out in the solid state, VCD delivers a very rich set of non-local contributions that are determined by crystal packing and collective motion. Since its discovery in the 1970s, VCD has become the method of choice for the determination of absolute configurations, but its applicability reaches beyond towards the study of different crystal forms and polymorphism. This brief review summarises the theoretical concepts of crystal chirality and how computations of solid-state VCD can shed light into the intimate connection of chiral structure and vibrational optical activity.
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Affiliation(s)
- Sascha Jähnigen
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
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4
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Jähnigen S, Le Barbu-Debus K, Guillot R, Vuilleumier R, Zehnacker A. How Crystal Symmetry Dictates Non-Local Vibrational Circular Dichroism in the Solid State. Angew Chem Int Ed Engl 2023; 62:e202215599. [PMID: 36441537 PMCID: PMC10107176 DOI: 10.1002/anie.202215599] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 11/29/2022]
Abstract
Solid-State Vibrational Circular Dichroism (VCD) can be used to determine the absolute structure of chiral crystals, but its interpretation remains a challenge in modern spectroscopy. In this work, we investigate the effect of a twofold screw axis on the solid-state VCD spectrum in a combined experimental and theoretical analysis of P21 crystals of (S)-(+)-1-indanol. Even though the space group is achiral, a single proper symmetry operation has an important impact on the VCD spectrum, which reflects the supramolecular chirality of the crystal. Distinguishing between contributions originating from molecular chirality and from chiral crystal packing, we find that while IR absorption hardly depends on the symmetry of the space group, the situation is different for VCD, where completely new non-local patterns emerge. Understanding the two underlying mechanisms, namely gauge transport and direct coupling, will help to use VCD to distinguish polymorphic forms.
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Affiliation(s)
- Sascha Jähnigen
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, CNRS, PSL University, Sorbonne Université, 75005, Paris, France
| | - Katia Le Barbu-Debus
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Rodolphe Vuilleumier
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, CNRS, PSL University, Sorbonne Université, 75005, Paris, France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405, Orsay, France
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5
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Taherivardanjani S, Blasius J, Brehm M, Dötzer R, Kirchner B. Conformer Weighting and Differently Sized Cluster Weighting for Nicotine and Its Phosphorus Derivatives. J Phys Chem A 2022; 126:7070-7083. [PMID: 36170053 DOI: 10.1021/acs.jpca.2c03133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Weighting methods applied to systems with many conformers have been broadly employed to calculate thermodynamic properties, structural characteristics, and populations. To better understand and test the sensitivity of conventional weighting methods, the conformational distributions of nicotine and its phosphorus-substituted derivatives are investigated. The weighting schemes used for this are all based on Boltzmann statistics. Classical Boltzmann factors based on the electronic energy and the Gibbs free energy are calculated at different quantum chemical levels of theory and compared to cluster weights obtained by the quantum cluster equilibrium method. Furthermore, the influence of the modified rigid-rotor-harmonic-oscillator (mRRHO) approximation on the cluster weights is investigated. The substitution of the nitrogen atom in the methylpyrrolidine ring by a phosphorus atom results in more monomer conformers and clusters being populated. The conformational distribution of the monomers remained stable at different levels of theory and weighting methods. However, going to dimers and trimers, we observe a significant influence of the level of theory, weighting method, and mRRHO cutoff on the populations of these clusters. We show that mRRHO cutoff values of 50 and 100 cm-1 yield similar results, which is why 50 cm-1 is recommended as a robust choice. Furthermore, we observe that the global minimum for ΔE0 and ΔG varies in a few cases and that the global minimum is not always the dominantly occupied structure.
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Affiliation(s)
- Shima Taherivardanjani
- Mulliken Center for Theoretical Chemistry, Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
| | - Jan Blasius
- Mulliken Center for Theoretical Chemistry, Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle (Saale), Germany
| | - Reinhard Dötzer
- Competence Center Analytics, BASF SE, D-67056 Ludwigshafen, Germany
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4 + 6, D-53115 Bonn, Germany
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6
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Golub TP, Feßner M, Engelage E, Merten C. Dynamic Stereochemistry of a Biphenyl-Bisprolineamide Model Catalyst and its Imidazolidinone Intermediates. Chemistry 2022; 28:e202201317. [PMID: 35611719 PMCID: PMC9545261 DOI: 10.1002/chem.202201317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Indexed: 12/15/2022]
Abstract
In this study, we characterize the dynamic stereochemistry of a biphenyl-2,2'-bis(proline amide) catalyst in chloroform and DMSO as representative weakly and strongly hydrogen bonding solvents. Using vibrational circular dichroism (VCD) spectroscopy and density functional theory (DFT) based spectra calculations, we show that the preferred axial stereochemistry of the catalyst is determined by solute-solvent interactions. Explicitly considering solvation with DMSO molecules is found to be essential to correctly predict the conformational preferences of the catalyst. Furthermore, we investigate the stereochemistry of the corresponding enamines and imidazolidinones that are formed upon reaction with isovaleraldehyde. The enamines are found to rapidly convert to endo-imidazolidinones and the thermodynamically favored exo-imidazolidinones are formed only slowly. The present study demonstrates that the stereochemistry of these imidazolidinones can be deduced directly from the VCD spectra analysis without any further detailed analysis of NMR spectra. Hence, we herein exemplify the use of VCD spectroscopy for an in situ characterization of intermediates relevant in asymmetric catalysts.
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Affiliation(s)
- Tino P. Golub
- Ruhr Universität BochumFakultät für Chemie und BiochemieOrganische Chemie IIUniversitätsstraße 15044801BochumGermany
| | - Malte Feßner
- Ruhr Universität BochumFakultät für Chemie und BiochemieOrganische Chemie IIUniversitätsstraße 15044801BochumGermany
| | - Elric Engelage
- Ruhr Universität BochumFakultät für Chemie und BiochemieOrganische Chemie IIUniversitätsstraße 15044801BochumGermany
| | - Christian Merten
- Ruhr Universität BochumFakultät für Chemie und BiochemieOrganische Chemie IIUniversitätsstraße 15044801BochumGermany
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7
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Weirich L, Tusha G, Engelage E, Schäfer LV, Merten C. VCD spectroscopy reveals conformational changes of chiral crown ethers upon complexation of potassium and ammonium cations. Phys Chem Chem Phys 2022; 24:11721-11728. [PMID: 35506489 DOI: 10.1039/d2cp01309f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two chiral derivatives of 18-crown-6, namely the host molecules 2,3-diphenyl- and 2-phenyl-18c6, serve as model systems to investigate whether VCD spectroscopy can be used to monitor conformational changes occurring upon complexation of guests. Host-guest complexes of both crown ethers were prepared by addition of KNO3. The more bulky 2,3-diphenyl-18c6 is found to undergo major conformational changes upon encapsulation of K+, which are revealed as characteristic changes of the VCD spectral signatures. In contrast, while 2-phenyl-18c6 also incorporates K+ into the macrocycle, strong conformational changes are not occurring and thus spectral changes are negligible. With an octyl ammonium cation as guest molecule, 2,3-diphenyl-18c6 shows the same conformational and spectral changes that were observed for K+-complexes. In addition, the asymmetric NH3-deformation modes are found to gain VCD intensity through an induced VCD process. An analysis of the vibrational spectra enables a differentiation of VCD active and inactive guest modes: There appears to be a correlation between the symmetry of the vibrational mode and the induced VCD intensity. While this finding makes the host-guest complexes interesting systems for future theoretical studies on the origin of induced VCD signatures, the observations described in this study demonstrate that VCD spectroscopy is indeed a suitable technique for the characterization of supramolecular host-guest complexes.
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Affiliation(s)
- Luisa Weirich
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
| | - Gers Tusha
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Theoretische Chemie, Universitätsstraße 150, 44801 Bochum, Germany
| | - Elric Engelage
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
| | - Lars V Schäfer
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Theoretische Chemie, Universitätsstraße 150, 44801 Bochum, Germany
| | - Christian Merten
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
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8
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Dupont J, Lepère V, Zehnacker A, Hartweg S, Garcia GA, Nahon L. Photoelectron Circular Dichroism as a Signature of Subtle Conformational Changes: The Case of Ring Inversion in 1-Indanol. J Phys Chem Lett 2022; 13:2313-2320. [PMID: 35245057 DOI: 10.1021/acs.jpclett.2c00074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Chirality plays a fundamental role in the molecular recognition processes. Molecular flexibility is also crucial in molecular recognition, allowing the interacting molecules to adjust their structures and hence optimize the interaction. Methods probing simultaneously chirality and molecular conformation are therefore crucially needed. Taking advantage of a possible control in the gas phase of the conformational distribution between the equatorial and axial conformers resulting from a ring inversion in jet-cooled 1-indanol, we demonstrate here the sensitivity of valence-shell photoelectron circular dichroism (PECD) to both chirality and subtle conformational changes, in a case where the photoelectron spectra of the two conformers are identical. For the highest occupied orbital, we observe a dramatic inversion of the PECD-induced photoelectron asymmetries, while the photoionization cross-section and usual anisotropy (β) parameter are completely insensitive to conformational isomerism. Such a sensitivity is a major asset for the ongoing developments of PECD-based techniques as a sensitive chiral (bio)chemical analytical tool in the gas phase.
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Affiliation(s)
- Jennifer Dupont
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Valéria Lepère
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, F-91405 Orsay, France
| | - Sebastian Hartweg
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
| | - Gustavo A Garcia
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
| | - Laurent Nahon
- Synchrotron Soleil, L'Orme des Merisiers, St. Aubin BP48, F-91192 Gif sur Yvette, France
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9
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Scholten K, Merten C. Solvation of the Boc-Val-Phe- nPr peptide characterized by VCD spectroscopy and DFT calculations. Phys Chem Chem Phys 2022; 24:3611-3617. [PMID: 35103263 DOI: 10.1039/d1cp05457k] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The conformational preferences of peptides are strongly determined by hydrogen bonding interactions. Intermolecular solute-solvent interactions compete with intramolecular interactions, which typically stabilize the secondary structure of the peptide. The analysis of vibrational circular dichroism (VCD) spectra can give insights into solvation-induced changes in the conformational distribution of small peptides. Here we describe the VCD spectroscopic characterization of the model peptide Boc-Val-Phe-nPr in chloroform as representative for a weakly interacting solvent and dimethyl sulfoxide (DMSO-d6) as a strongly hydrogen bonding solvent. We show that the conformational preferences of the peptide in chloroform are well-described by the computationally predicted distribution of the isolated molecule assuming only implicit solvation effects through a continuum solvation model. In order to simulate the spectra recorded in DMSO-d6, solvation was accounted for explicitly by computed microsolvated structures containing one to three solvent molecules. A good match of the computed spectra with the experimental data is obtained by this method. Comparing the conformational distributions in deuterated chloroform-d1 and DMSO-d6, structures with intramolecular hydrogen bonds such as the (δ,δ)-conformer family contribute to the conformational distribution only when there is no strong interaction with the solvent. This is in contrast to the results for the related Boc-Pro-Phe-nPr studied before, for which the intramolecular interaction was found to persist in DMSO-d6. Furthermore, we discuss the influence of hydrogen bonding to different numbers of solvent molecules on the spectral signatures and show that the structure of the peptide in DMSO-d6 is best described as a mixture of twofold-solvated (δ,β)- and threefold-solvated (β,β)-conformers.
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Affiliation(s)
- Kevin Scholten
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
| | - Christian Merten
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
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10
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Le Barbu-Debus K, Zehnacker A. Competition between inter and intramolecular hydrogen bond evidenced by vibrational circular dichroism spectroscopy: The case of (1S,2R)-(-)-cis-1-amino-2-indanol. Chirality 2021; 33:858-874. [PMID: 34570370 DOI: 10.1002/chir.23362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 02/06/2023]
Abstract
The infrared (IR) absorption and vibrational circular dichroism (VCD) spectra of an intramolecularly hydrogen-bonded chiral amino-alcohol, (1S,2R)-(-)-cis-1-amino-2-indanol, are studied in DMSO-d6 . The spectra are simulated at the density functional theory (DFT) level within the frame of the cluster-in-the-liquid model. Both IR and VCD spectra show a clear signature of the formation of intermolecular hydrogen bonds at the detriment of the intramolecular OH … N interaction present in the isolated molecule. Two solvent molecules are necessary to reproduce the experimental spectra. Whereas the first DMSO molecule captures the main spectral modifications due to hydrogen bond formation between the solute and the solvent, the second DMSO molecule is necessary for a good description of the Boltzmann contribution of the different complexes, based on their Gibbs free energy.
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Affiliation(s)
- Katia Le Barbu-Debus
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, Orsay, France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, Orsay, France
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11
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Jähnigen S, Sebastiani D, Vuilleumier R. The important role of non-covalent interactions for the vibrational circular dichroism of lactic acid in aqueous solution. Phys Chem Chem Phys 2021; 23:17232-17241. [PMID: 34369531 DOI: 10.1039/d1cp03106f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We present a computational study of vibrational circular dichroism (VCD) in solutions of (S)-lactic acid, relying on ab initio molecular dynamics (AIMD) and full solvation with bulk water. We discuss the effect of the hydrogen bond network on the aggregation behaviour of the acid: while aggregates of the solute represent conditions encountered in a weakly interacting solvent, the presence of water drastically interferes with the clusters - more strongly than originally anticipated. For both scenarios we computed the VCD spectra by means of nuclear velocity perturbation theory (NVPT). The comparison with experimental data allows us to establish a VCD-structure relationship that includes the solvent network around the chiral solute. We suggest that fundamental modes with strong polarisation such as the carbonyl stretching vibration can borrow VCD from the chirally restructured solvent cage, which extends the common explanatory models of VCD generation in aqueous solution.
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Affiliation(s)
- Sascha Jähnigen
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France.
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12
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Demarque DP, Kemper M, Merten C. VCD spectroscopy reveals that a water molecule determines the conformation of azithromycin in solution. Chem Commun (Camb) 2021; 57:4031-4034. [PMID: 33885696 DOI: 10.1039/d1cc00932j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the IR and VCD spectra of azithromycin, a macrolide antibiotic with a total of 18 stereogenic centers. The computational analysis of the spectra reveals that a single water molecule has to be considered in the conformational search. Its key role is the stabilization of an extended hydrogen bonding network and an otherwise unstable conformation that determines the VCD spectral signatures.
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Affiliation(s)
- Daniel P Demarque
- Ruhr-Universität Bochum, Organische Chemie 2, Stereochemistry and Chiroptical Spectroscopy, Universitätsstraße 150, 44801 Bochum, Germany.
| | - Michael Kemper
- Ruhr-Universität Bochum, Organische Chemie 2, Stereochemistry and Chiroptical Spectroscopy, Universitätsstraße 150, 44801 Bochum, Germany.
| | - Christian Merten
- Ruhr-Universität Bochum, Organische Chemie 2, Stereochemistry and Chiroptical Spectroscopy, Universitätsstraße 150, 44801 Bochum, Germany.
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13
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Hernandez-Castillo AO, Bischoff J, Lee JH, Langenhan J, Karra M, Meijer G, Eibenberger-Arias S. High-resolution UV spectroscopy of 1-indanol. Phys Chem Chem Phys 2021; 23:7048-7056. [PMID: 33625420 DOI: 10.1039/d0cp06170k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report on rotationally resolved laser induced fluorescence (LIF) and vibrationally resolved resonance-enhanced multiphoton ionization (REMPI) spectroscopy of the chiral molecule 1-indanol. Spectra of the S1← S0 electronic transition are recorded in a jet-cooled, pulsed molecular beam. Using two time-delayed pulsed lasers, the lifetimes of the S1 state of the two most stable conformers, referred to as eq1 and ax2, have been determined. The S1← S0 origin bands of these conformers as well as the transition to a vibrationally excited level in the S1 state of eq1 are recorded with full rotational resolution (25 MHz observed linewidth) by measuring the LIF intensity following excitation with a tuneable, narrowband cw laser. On selected rotationally resolved electronic transitions, Lamb-dips are measured to confirm the Lorentzian lifetime-contribution to the observed lineshapes. The rotationally resolved S1← S0 origin band of a neon-complex of eq1 is measured via LIF as well. The fit of the rotationally resolved LIF spectra of the origin bands to those of an asymmetric rotor yields a standard deviation of about 6 MHz. The resulting spectroscopic parameters are tabulated and compared to the outcome of ab initio calculations. For both conformers as well as for the Ne-eq1 complex, the geometric structures in the S0 and S1 states are discussed. For all systems, the transition dipole moment is mainly along the a-axis, the contributions along the b- and c-axes being about one order of magnitude smaller.
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Affiliation(s)
- A O Hernandez-Castillo
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
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14
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Polavarapu PL, Santoro E, Covington CL, Johnson JL, Puente AR, Schley ND, Kallingathodi Z, Prakasan PC, Haleema S, Thomas AA, Ibnusaud I. How important are the intermolecular hydrogen bonding interactions in methanol solvent for interpreting the chiroptical properties? SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 247:119094. [PMID: 33142265 DOI: 10.1016/j.saa.2020.119094] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/10/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Two crispine A analogs and tetrahydrofuro[2,3-b]furan-3,3a(6aH)-diol, endowed with hydroxyl groups that can participate in intramolecular hydrogen bonding, have been synthesized and experimental vibrational circular dichroism (VCD) spectra and optical rotatory dispersion (ORD) data have been measured in CD3OD/CH3OH solvents. The absolute configurations (ACs) of these compounds have been determined using their synthetic schemes, supplemented wherever possible with X-ray diffraction data. The ACs are also analyzed with quantum chemical (QC) calculations of VCD and ORD utilizing implicit solvation as well as explicit solvation models, with the later employing classical molecular dynamics (MD) simulations. It is found that VCD calculations with implicit solvation model are adequate for determining the ACs, despite propensity of studied compounds for intermolecular hydrogen bonding between solute and solvent molecules. This observation is important because time-consuming MD simulations may not be necessary in the type of situations studied here. Additionally, it is found that the QC predicted VCD spectra provided enough diastereomer discrimination for determining the correct AC of studied compounds independently. The same observation did not apply to ORD.
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Affiliation(s)
| | - Ernesto Santoro
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Cody L Covington
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Austin Peay State University, Clarksville, TN 37044, USA
| | - Jordan L Johnson
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Andrew R Puente
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Nathan D Schley
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
| | - Zabeera Kallingathodi
- Institute for Integrated Programmes and Research in Basic Sciences, Mahatma Gandhi University, Kottayam 686560, India
| | - Prasanth C Prakasan
- Institute for Integrated Programmes and Research in Basic Sciences, Mahatma Gandhi University, Kottayam 686560, India
| | - Simimole Haleema
- Institute for Integrated Programmes and Research in Basic Sciences, Mahatma Gandhi University, Kottayam 686560, India
| | - Annu Anna Thomas
- Institute for Integrated Programmes and Research in Basic Sciences, Mahatma Gandhi University, Kottayam 686560, India
| | - Ibrahim Ibnusaud
- Institute for Integrated Programmes and Research in Basic Sciences, Mahatma Gandhi University, Kottayam 686560, India.
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15
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Weirich L, Blanke K, Merten C. More complex, less complicated? Explicit solvation of hydroxyl groups for the analysis of VCD spectra. Phys Chem Chem Phys 2020; 22:12515-12523. [DOI: 10.1039/d0cp01656j] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
With increasing size of the molecules, hydrogen bonding induced solvent effects on the IR and VCD spectra become more negligible.
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Affiliation(s)
- Luisa Weirich
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | - Katharina Blanke
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | - Christian Merten
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
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16
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Weirich L, Magalhães de Oliveira J, Merten C. How many solvent molecules are required to solvate chiral 1,2-diols with hydrogen bonding solvents? A VCD spectroscopic study. Phys Chem Chem Phys 2020; 22:1525-1533. [DOI: 10.1039/c9cp06030h] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A VCD spectroscopic analysis of selected model systems for solute–solvent interactions of chiral diols with hydrogen bonding solvents DMSO and ACN.
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Affiliation(s)
- Luisa Weirich
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | | | - Christian Merten
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
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17
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Le Barbu-Debus K, Bowles J, Jähnigen S, Clavaguéra C, Calvo F, Vuilleumier R, Zehnacker A. Assessing cluster models of solvation for the description of vibrational circular dichroism spectra: synergy between static and dynamic approaches. Phys Chem Chem Phys 2020; 22:26047-26068. [DOI: 10.1039/d0cp03869e] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Solvation effects are essential for defining the shape of vibrational circular dichroism (VCD) spectra.
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Affiliation(s)
- Katia Le Barbu-Debus
- Institut des Sciences Moléculaires d’Orsay (ISMO)
- CNRS
- Université Paris-Saclay
- F-91405 Orsay
- France
| | - Jessica Bowles
- Université Paris-Saclay
- CNRS
- Institut de Chimie Physique
- UMR8000
- 91405 Orsay
| | - Sascha Jähnigen
- PASTEUR
- Département de Chimie
- Ecole Normale Supérieure
- PSL University
- Sorbonne Université
| | - Carine Clavaguéra
- Université Paris-Saclay
- CNRS
- Institut de Chimie Physique
- UMR8000
- 91405 Orsay
| | - Florent Calvo
- Université Grenoble Alpes
- CNRS
- LiPhy
- F-38000 Grenoble
- France
| | - Rodolphe Vuilleumier
- PASTEUR
- Département de Chimie
- Ecole Normale Supérieure
- PSL University
- Sorbonne Université
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d’Orsay (ISMO)
- CNRS
- Université Paris-Saclay
- F-91405 Orsay
- France
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18
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Declerck V, Pérez‐Mellor A, Guillot R, Aitken DJ, Mons M, Zehnacker A. Vibrational circular dichroism as a probe of solid‐state organisation of derivatives of cyclic β‐amino acids:
Cis
‐ and
trans
‐2‐aminocyclobutane‐1‐carboxylic acid. Chirality 2019; 31:547-560. [DOI: 10.1002/chir.23083] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Valérie Declerck
- CP3A Organic Synthesis Group and Services Communs, ICMMO, UMR 8182Université Paris Sud, Université Paris‐Saclay Orsay France
| | - Ariel Pérez‐Mellor
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris‐SudUniversité Paris‐Saclay Orsay France
| | - Régis Guillot
- CP3A Organic Synthesis Group and Services Communs, ICMMO, UMR 8182Université Paris Sud, Université Paris‐Saclay Orsay France
| | - David J. Aitken
- CP3A Organic Synthesis Group and Services Communs, ICMMO, UMR 8182Université Paris Sud, Université Paris‐Saclay Orsay France
| | - Michel Mons
- Laboratoire Interactions Dynamiques et Lasers (LIDYL)Université Paris Saclay Paris France
| | - Anne Zehnacker
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris‐SudUniversité Paris‐Saclay Orsay France
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19
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Johnson J, Polavarapu PL. Chiral Molecular Structures of Substituted Indans: Ring Puckering, Rotatable Substituents, and Vibrational Circular Dichroism. ACS OMEGA 2019; 4:4963-4976. [PMID: 31459680 PMCID: PMC6648482 DOI: 10.1021/acsomega.8b03628] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 02/21/2019] [Indexed: 05/06/2023]
Abstract
The chiral molecular structures of four different substituted indans, namely, (S)-1-methylindan, (R)-1-methylindan-1-d, (R)-1-aminoindan, and (S)-1-indanol, were investigated using experimental vibrational absorption and vibrational circular dichroism spectra and corresponding spectra predicted using quantum chemical (QC) calculations. All of these molecules possess two ring puckering conformations, with ring puckering leading to the pseudoequatorial substituent being approximately four times more abundant over that leading to the pseudoaxial substituent. The amino group in 1-aminoindan has three conformations arising from the rotation of NH2 group, for each ring puckering conformation, resulting in a total of six conformations. Whereas 1-indanol in the nonhydrogen-bonding solvent CCl4 also has six conformations similar to those of 1-aminoindan, 1-indanol in the hydrogen-bonding solvent DMSO-d 6 adopts numerous conformations, of which 30 conformers are considered to have at least ∼1% or more population. In DMSO solution, ring puckering leading to pseudoequatorial substituent accounts for 77% population and 23% for pseudoaxial substituent. The QC spectra predicted for the geometry optimized conformers are found to be in excellent quantitative agreement with corresponding experimental spectra in all of the molecules considered. The procedures suggested in this work are hoped to provide successful pathways for future chiral molecular structural analyses.
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20
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Weirich L, Merten C. Solvation and self-aggregation of chiral alcohols: how hydrogen bonding affects their VCD spectral signatures. Phys Chem Chem Phys 2019; 21:13494-13503. [DOI: 10.1039/c9cp01407a] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
IR and VCD spectra of chiral alcohols in different solvents are analyzed with DFT spectra calculations. We show that for ACN or DMSO explicit solvation is needed to reproduce experimental spectra.
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Affiliation(s)
- Luisa Weirich
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | - Christian Merten
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
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