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Novelli F, Friebel P, Murillo-Sanchez ML, Michael Klopf J, Cattaneo L. Liquid crystal wave plate operating close to 18 THz. OPTICS LETTERS 2024; 49:2061-2064. [PMID: 38621076 DOI: 10.1364/ol.519177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 03/09/2024] [Indexed: 04/17/2024]
Abstract
Controlling the properties of mid- and far-infrared radiation can provide a means to transiently alter the properties of materials for novel applications. However, a limited number of optical elements are available to control its polarization state. Here we show that a 15-µm thick liquid crystal cell containing 8CB (4-octyl-4'-cyanobiphenyl) in the ordered, smectic A phase can be used as a phase retarder or wave plate. This was tested using the bright, short-pulsed (∼1 ps) radiation centered at 16.5 µm (18.15 THz) that is emitted by a free electron laser at high repetition rate (13 MHz). These results demonstrate a possible tool for the exploration of the mid- and far-infrared range and could be used to develop novel metamaterials or extend multidimensional spectroscopy to this portion of the electromagnetic spectrum.
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2
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Dobšíková K, Taušová T, Fagan P, Paškanová N, Kuchař M, Čejka J, Setnička V. Solid-state vibrational circular dichroism: Methodology and application for amphetamine derivatives. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 305:123486. [PMID: 37820493 DOI: 10.1016/j.saa.2023.123486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/22/2023] [Accepted: 10/01/2023] [Indexed: 10/13/2023]
Abstract
Amphetamine derivatives are considered most seized substances worldwide. In this study, solid-state vibrational circular dichroism (VCD) measurements of enantiomerically pure substances were performed for spectroscopic discrimination between (S)- and (R)-enantiomers. First, we have developed a universal experimental approach to obtain reliable and reproducible solid-state VCD spectra. First, the samples were prepared as pellets composed of mixtures of camphor as a model compound and a crystalline matrix powder. In order to obtain the best results without artifacts and with a maximum signal-to-noise ratio, the following experimental conditions were optimized: pellet thickness and diameter and sample rotation speed. The optimized parameters were then used for the analysis of amphetamine and its derivatives (methamphetamine and 3,4-methylendioxymethamphetamine). Our high-quality spectra and results suggest that solid-state VCD spectroscopy represents a cost-effective and easy-to-use method for the analysis of conformation changes and molecular packing in solid-state with potential applications in pharmaceutical and forensic practice.
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Affiliation(s)
- K Dobšíková
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic
| | - T Taušová
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic
| | - P Fagan
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic
| | - N Paškanová
- Forensic Laboratory of Biologically Active Substances, Department of Chemistry of Natural Compounds, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic
| | - M Kuchař
- Forensic Laboratory of Biologically Active Substances, Department of Chemistry of Natural Compounds, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic; Psychedelic Research Centre, National Institute of Mental Health, Topolová 748, Klecany 250 67, Czech Republic
| | - J Čejka
- Department of Solid State Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic
| | - V Setnička
- Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, Prague 6 166 28, Czech Republic.
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3
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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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4
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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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5
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Taniguchi T, Agbo DO. Vibrational circular dichroism spectroscopy in the C-D, XY, and XYZ stretching region. Phys Chem Chem Phys 2023; 25:28567-28575. [PMID: 37861094 DOI: 10.1039/d3cp04287a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Vibrational circular dichroism (VCD) spectroscopy is a powerful technique for structural analysis of chiral molecules, but information available from VCD spectra of large molecular systems can be limited by severe overlap of vibrational bands. While common chiral molecules do not absorb in the 1900-2400 cm-1 region, observation of VCD signals in this spectrally-isolated region is possible for molecules containing C-D, XY, and XYZ chromophores. Thus, a strategic introduction of these chromophores to a target molecule may produce VCD signals informative for molecular structures. VCD spectroscopy in the 1900-2400 cm-1 region is a rather unexplored research field and its basic properties remain to be investigated. This perspective article discusses insight obtained so far on the usefulness and physicochemical aspects of VCD spectroscopy in this region with briefly summarizing previous experimental VCD studies including classic examples as well as our recent results. We show that anharmonic effects such as overtones and combination bands often complicate VCD patterns. On the other hand, some molecules exhibit characteristic VCD signals that can be well interpreted by harmonic DFT spectral calculations for structural analysis. This article also discusses several examples of the use of this region for studying solute-solvent interactions and for VCD signal augmentation.
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Affiliation(s)
- Tohru Taniguchi
- Frontier Research Center for Advanced Material and Life Science, Faculty of Advanced Life Science, Hokkaido University, North 21 West 11, Sapporo 001-0021, Japan.
| | - Davidson Obinna Agbo
- Graduate School of Life Science, Hokkaido University, North 21 West 11, Sapporo 001-0021, Japan
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6
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Böselt L, Aerts R, Herrebout W, Riniker S. Improving the IR spectra alignment algorithm with spectra deconvolution and combination with Raman or VCD spectroscopy. Phys Chem Chem Phys 2023; 25:2063-2074. [PMID: 36546852 PMCID: PMC9847344 DOI: 10.1039/d2cp04907d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The relative stereochemistry of organic molecules can be determined by comparing theoretical and experimental infrared (IR) spectra of all isomers and assessing the best match. For this purpose, we have recently developed the IR spectra alignment (IRSA) algorithm for automated optimal alignment. IRSA provides a set of quantitative metrics to identify the candidate structure that agrees best with the experimental spectrum. While the correct diastereomer could be determined for the tested sets of rigid and flexible molecules, two issues were identified with more complex compounds that triggered further development. First, strongly overlapping peaks in the IR spectrum are not treated adequately in the current IRSA implementation. Second, the alignment of multiple spectra from different sources (e.g. IR and VCD or Raman) can be improved. In this study, we present an in-depth discussion of these points, followed by the description of modifications to the IRSA algorithm to address them. In particular, we introduce the concept of deconvolution of the experimental and theoretical spectra with a set of pseudo-Voigt bands. The pseudo-Voigt bands have a set of parameters, which can be employed in the alignment algorithm, leading to improved scoring functions. We test the modified algorithm on two data sets. The first set contains compounds with IR and Raman spectra measured in this study, and the second set contains compounds with IR and VCD spectra available in the literature. We show that the algorithm is able to determine the correct diastereomer in all cases. The results highlight that vibrational spectroscopy can be a valuable alternative or complementary method to inform about the stereochemistry of compounds, and the performance of the updated IRSA algorithm suggests that it is a powerful tool for quantitative-based spectral assignments in academia and industry.
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Affiliation(s)
- Lennard Böselt
- Laboratory of Physical Chemistry, ETH ZürichVladimir-Prelog-Weg 28093 ZürichSwitzerland
| | - Roy Aerts
- Department of Chemistry, University of AntwerpGroenenborgerlaan 171B-2020 AntwerpBelgium
| | - Wouter Herrebout
- Department of Chemistry, University of AntwerpGroenenborgerlaan 171B-2020 AntwerpBelgium
| | - Sereina Riniker
- Laboratory of Physical Chemistry, ETH ZürichVladimir-Prelog-Weg 28093 ZürichSwitzerland
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7
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Machalska E, Zając G, Rode JE. Chirality transfer observed in Raman optical activity spectra. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 281:121604. [PMID: 35835058 DOI: 10.1016/j.saa.2022.121604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/28/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
Chirality transfer (also called induced chirality) is a phenomenon present in chiroptical spectra that manifests itself as a new band or bands of an achiral molecule interacting with a chiral one. In the Raman optical activity (ROA) spectroscopy, the bands of achiral solvents have been recently observed, but the latest papers have shown that they corresponded to the new ECD-Raman (eCP-Raman) effect. Here, we show an unambiguous example of chirality transfer observed in the ROA spectra. The spectra registered for the (1:1) mixtures of achiral benzonitrile with the enantiomers of 2,2,2-trifluoro-1-phenylethanol, 1-phenylethanol, and 1-phenylethylamine exhibited the v(CN) vibration band at about 2230 cm-1. The ROA measurements were repeated several times to ensure the reliability of the phenomenon. Calculations revealed the CN···HO or CN···HNH hydrogen bond formation accompanied by the π···π or CH···π interactions. The interaction strength was shown to be an important factor for the pronouncement of the ROA chirality transfer effect.
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Affiliation(s)
- Ewa Machalska
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-38 Krakow, Poland; Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Bobrzynskiego 14, 30-348 Krakow, Poland.
| | - Grzegorz Zając
- Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Bobrzynskiego 14, 30-348 Krakow, Poland.
| | - Joanna E Rode
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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8
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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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9
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Aerts R, Bogaerts J, Herrebout W, Johannessen C. Insights in the vibrational optical activity spectra of the antibiotic vancomycin in DMSO. Phys Chem Chem Phys 2022; 24:9619-9625. [PMID: 35403645 DOI: 10.1039/d2cp00746k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vibrational circular dichroism (VCD) and Raman optical activity (ROA) are two spectroscopic techniques that are sensitive towards the conformational behaviour of molecules, and are often complementary herein. In this work we pursue the determination of the conformational ensemble of the antibiotic glycopeptide vancomycin in DMSO through comparison of experimental and computational spectra, both for VCD and ROA. ROA is found to be highly suitable for the task, identifying an ensemble that strongly resembles the NMR conformation. In the case of VCD, however, a too high sensitivity of the intensities with respect to minor conformational changes hampers a reliable conformational analysis. Whence attempting to improve the match between the VCD experiment and calculations by any means - e.g., by inducing minor conformational changes or including solvent effects in the calculations - we show that there is the risk of going down the rabbit hole. In conclusion, this work contributes to the broader understanding of where, when and how VCD and ROA can be deployed as techniques for conformational analysis.
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Affiliation(s)
- Roy Aerts
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
| | - Jonathan Bogaerts
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
| | - Wouter Herrebout
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
| | - Christian Johannessen
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
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10
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Rode JE, Lyczko K, Kosińska K, Matalińska J, Dyniewicz J, Misicka A, Dobrowolski JC, Lipiński PFJ. The solid state VCD of a novel N-acylhydrazone trifluoroacetate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 269:120761. [PMID: 34954483 DOI: 10.1016/j.saa.2021.120761] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/23/2021] [Accepted: 12/12/2021] [Indexed: 06/14/2023]
Abstract
A novel N-acylhydrazone with pharmaceutical importance was subject of structural and IR/VCD investigations in the solid state. In the crystal structure, dimers of anion-cation pairs are stabilized by H-bonding and ionic interactions. Some less common interaction types, like C=N···C-NH3+ (σ-hole) interactions, hydrazone-aromatic interactions and dispersive contacts of the CF3 groups are also present in the crystal. Satisfactory reproduction of the solid state IR and VCD spectra required that quantum-chemical calculations be done on a tetramer (four cation-anion pairs) cut out from the crystal structure, exhibiting key intermolecular interactions. Ten DFT functionals were assessed as to the agreement between the calculated and experimental spectra. Various approaches to scaling of the calculated frequencies were applied. The best results were yielded with individual (optimized) frequency scaling factors (FSFs) and band half-widths at half maximum-(HWHM) for four separate spectral subregions. The best matching between the experimental and theoretical spectra (according to SimIR, SimVCD and SimVDF indices) was found for the B3PW91 functional, however, a few other functionals follow closely in the ranking. Based on the quantum chemical calculations, spectral assignments have been made.
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Affiliation(s)
- Joanna E Rode
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Street, PL 03-195 Warsaw, Poland
| | - Krzysztof Lyczko
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Street, PL 03-195 Warsaw, Poland
| | - Katarzyna Kosińska
- Department of Neuropeptides, Mossakowski Medical Research Institute Polish Academy of Sciences, 5 Pawińskiego Street, PL 02-106 Warsaw, Poland
| | - Joanna Matalińska
- Department of Neuropeptides, Mossakowski Medical Research Institute Polish Academy of Sciences, 5 Pawińskiego Street, PL 02-106 Warsaw, Poland
| | - Jolanta Dyniewicz
- Department of Neuropeptides, Mossakowski Medical Research Institute Polish Academy of Sciences, 5 Pawińskiego Street, PL 02-106 Warsaw, Poland
| | - Aleksandra Misicka
- Department of Neuropeptides, Mossakowski Medical Research Institute Polish Academy of Sciences, 5 Pawińskiego Street, PL 02-106 Warsaw, Poland
| | - Jan Cz Dobrowolski
- Department for Medicines Biotechnology and Bioinformatics, National Medicines Institute, 30/34 Chełmska Street, PL 00-725 Warsaw, Poland
| | - Piotr F J Lipiński
- Department of Neuropeptides, Mossakowski Medical Research Institute Polish Academy of Sciences, 5 Pawińskiego Street, PL 02-106 Warsaw, Poland.
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11
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Golub T, Kano T, Maruoka K, Merten C. VCD spectroscopy distinguishes the enamine and iminium ion of a 1,1’-binaphthyl azepine. Chem Commun (Camb) 2022; 58:8412-8415. [DOI: 10.1039/d2cc02863h] [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
We present a VCD spectroscopic characterization of a chiral 1,1’-binaphthyl azepine catalyst and show that the VCD spectra of an in-situ generated enamine and an ex-situ prepared iminium ion are...
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12
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Omor Faruk Patwary M, Mahbubur Rahman M, Khalid Bin Islam M, Ackas Ali M, Halim MA, Ahmed F. Probing the non-bonding interaction of small molecules with graphene oxide using DFT based vibrational circular dichroism. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2021.113503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Górecki M, Frelek J. A Holistic Approach to Determining Stereochemistry of Potential Pharmaceuticals by Circular Dichroism with β-Lactams as Test Cases. Int J Mol Sci 2021; 23:273. [PMID: 35008698 PMCID: PMC8745598 DOI: 10.3390/ijms23010273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 11/17/2022] Open
Abstract
This paper's main objective is to show that many different factors must be considered when solving stereochemical problems to avoid misleading conclusions and obtain conclusive results from the analysis of spectroscopic properties. Particularly in determining the absolute configuration, the use of chiroptical methods is crucial, especially when other techniques, including X-ray crystallography, fail, are not applicable, or give inconclusive results. Based on various β-lactam derivatives as models, we show how to reliably determine their absolute configuration (AC) and preferred conformation from circular dichroism (CD) spectra. Comprehensive CD analysis, employing both approaches, i.e., traditional with their sector and helicity rules, and state-of-the-art supported by quantum chemistry (QC) calculations along with solvation models for both electronic (ECD) and vibrational (VCD) circular dichroism ranges, allows confident defining stereochemistry of the β-lactams studied. Based on an in-depth analysis of the results, we have shown that choosing a proper chiroptical method/s strictly depends on the specific case and certain structural features.
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Affiliation(s)
- Marcin Górecki
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 St., 01-224 Warsaw, Poland;
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14
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Taniguchi T, Zubir MZM, Harada N, Monde K. Exploration of chromophores for a VCD couplet in a spectrally transparent infrared region for biomolecules. Phys Chem Chem Phys 2021; 23:27525-27532. [PMID: 34874381 DOI: 10.1039/d1cp04074j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Interactions of two chromophores such as carbonyl groups yield a strong VCD couplet that reflects the molecular structures. The use of VCD couplets for biomacromolecular structural studies has been hampered by severe signal overlap caused by numerous functional groups that originally exist in biomacromolecules. Nitrile, isonitrile, alkyne, and azido groups show characteristic IR absorption in the 2300-2000 cm-1 region, where biomolecules do not strongly absorb. We herein examined the usefulness of these functional groups as chromophores to observe a strong VCD couplet that can be readily interpreted using theoretical calculations. Studies on a chiral binaphthyl scaffold possessing two identical chromophores showed that nitrile and isonitrile groups generate moderately-strong but complex VCD signals due to anharmonic contributions. The nature of their anharmonic VCD patterns is discussed by comparison with the VCD spectrum of a mono-chromophoric molecule and by anharmonic DFT calculations. On the other hand, through studies on diazido binaphthyl and diazido monosaccharide, we demonstrated that the azido group is more promising for structural analysis of larger molecules due to its simple, strong VCD couplet whose spectral patterns are readily predicted by harmonic DFT calculations.
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Affiliation(s)
- Tohru Taniguchi
- Frontier Research Center for Advanced Material and Life Science, Faculty of Advanced Life Science, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan.
| | | | - Nobuyuki Harada
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Kenji Monde
- Frontier Research Center for Advanced Material and Life Science, Faculty of Advanced Life Science, Hokkaido University, Kita 21 Nishi 11, Sapporo 001-0021, Japan.
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15
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Golub TP, Merten C. Vibrational CD study on the solution phase structures of the MacMillan catalyst and its corresponding iminium ion. Phys Chem Chem Phys 2021; 23:25162-25169. [PMID: 34730148 DOI: 10.1039/d1cp04497d] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We demonstrate that VCD spectroscopy can reveal insights into the conformational preferences of the iminium ion obtained from MacMillan's imidazolidinone catalyst. For both the isolated and in situ generated iminium ion, the comparison of experimental and computed VCD spectra directly confirms that conformer 2b ("Houk-conformer") is the dominant structure in solution. This conclusion is reached without any in-depth interpretation of the spectroscopic data, just by visual comparison of the spectral signatures. For the parent catalyst 1 and its salts 1·HCl and 1·HClO4, we report a comprehensive analysis of the conformational preferences in two solvents. VCD spectroscopy is subsequently shown to be able to reveal small conformational changes induced by solute-solvent and solute-anion interactions.
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Affiliation(s)
- Tino P Golub
- 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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16
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Weirich L, Merten C. Induced VCD and conformational chirality in host-guest complexes of a chiral ammonium salt with crown ethers. Phys Chem Chem Phys 2021; 23:18300-18307. [PMID: 34114592 DOI: 10.1039/d1cp01846a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The hydrogen bonded complexes of the chiral ammonium salt α-methylbenzyl ammonium chloride (MBA-H+Cl-) and the achiral crown ethers 18c6 and 15c5 serve as model systems to investigate the effect of host-guest complex formation on the conformational preferences of the macrocycles. We demonstrate that the intermolecular interactions result in new VCD signatures, that can be assigned to vibrational modes of the crown ethers. Based on a detailed conformational analysis, we investigate the origin of these signatures and discuss induced VCD (iVCD) and conformational chirality as possible sources of VCD intensity. The macrocycle in the MBA-H+/18c6 complex prefers either an achiral D3d-symmetric conformation, which gives rise to iVCD, or chiral conformations, that feature individual contributions to the VCD spectrum. For the MBA-H+/15c5 complex, the contributions of the macrocycle to the VCD signatures are less pronounced and found to arise solely from conformational chirality. Therefore, analysis of the VCD signatures confirms that the small chiral guest molecule is able to affect the conformational preferences of a macrocyclic host. The study thus demonstrates the suitability of VCD spectroscopy for the characterization of analogous 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.
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17
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Bogaerts J, Aerts R, Vermeyen T, Johannessen C, Herrebout W, Batista JM. Tackling Stereochemistry in Drug Molecules with Vibrational Optical Activity. Pharmaceuticals (Basel) 2021; 14:877. [PMID: 34577577 PMCID: PMC8468215 DOI: 10.3390/ph14090877] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 12/29/2022] Open
Abstract
Chirality plays a crucial role in drug discovery and development. As a result, a significant number of commercially available drugs are structurally dissymmetric and enantiomerically pure. The determination of the exact 3D structure of drug candidates is, consequently, of paramount importance for the pharmaceutical industry in different stages of the discovery pipeline. Traditionally the assignment of the absolute configuration of druggable molecules has been carried out by means of X-ray crystallography. Nevertheless, not all molecules are suitable for single-crystal growing. Additionally, valuable information about the conformational dynamics of drug candidates is lost in the solid state. As an alternative, vibrational optical activity (VOA) methods have emerged as powerful tools to assess the stereochemistry of drug molecules directly in solution. These methods include vibrational circular dichroism (VCD) and Raman optical activity (ROA). Despite their potential, VCD and ROA are still unheard of to many organic and medicinal chemists. Therefore, the present review aims at highlighting the recent use of VOA methods for the assignment of the absolute configuration of chiral small-molecule drugs, as well as for the structural analysis of biologics of pharmaceutical interest. A brief introduction on VCD and ROA theory and the best experimental practices for using these methods will be provided along with selected representative examples over the last five years. As VCD and ROA are commonly used in combination with quantum calculations, some guidelines will also be presented for the reliable simulation of chiroptical spectra. Special attention will be paid to the complementarity of VCD and ROA to unambiguously assess the stereochemical properties of pharmaceuticals.
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Affiliation(s)
- Jonathan Bogaerts
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium; (J.B.); (R.A.); (T.V.); (C.J.); (W.H.)
| | - Roy Aerts
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium; (J.B.); (R.A.); (T.V.); (C.J.); (W.H.)
| | - Tom Vermeyen
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium; (J.B.); (R.A.); (T.V.); (C.J.); (W.H.)
- Department of Chemistry, Ghent University, 9000 Ghent, Belgium
| | - Christian Johannessen
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium; (J.B.); (R.A.); (T.V.); (C.J.); (W.H.)
| | - Wouter Herrebout
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium; (J.B.); (R.A.); (T.V.); (C.J.); (W.H.)
| | - Joao M. Batista
- Institute of Science and Technology, Federal University of Sao Paulo, Sao Jose dos Campos 12231-280, SP, Brazil
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18
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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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19
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Yang Y, Cheramy J, Xu Y. Matrix Isolation-Vibrational Circular Dichroism Spectroscopic Study of Conformations and Non-Covalent Interactions of Tetrahydro-2-Furoic Acid. Chemphyschem 2021; 22:1336-1343. [PMID: 33945674 DOI: 10.1002/cphc.202100256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/01/2021] [Indexed: 11/10/2022]
Abstract
The conformational landscape and aggregation behaviour of tetrahydro-2-furoic acid (THFA) were investigated by using matrix isolation-vibrational circular dichroism (MI-VCD). The well-resolved experimental MI-IR and MI-VCD features in an argon matrix at 10 K allow one to identify two dominant monomeric conformations as trans-THFA where the hydroxyl and carbonyl groups of COOH are at opposite sides, as well as one cis-conformer. At 24 K and 30 K deposition temperatures, the experimental IR and VCD spectral features reveal further growth of the binary THFA aggregates. Systematic conformational searches identified three vastly different binary binding topologies, resulting in a few hundred stable (THFA)2 conformers. Interestingly, the main binary structures observed correspond to an unusual type of structure which is made of two trans-THFA subunits, in contrast to the usual double H-bonded ring binary structures, identified in a previous solution study. The present work showcases the power of MI-VCD spectroscopy in revealing unusual structures formed in a cold rare gas matrix.
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Affiliation(s)
- Yanqing Yang
- Chemistry Department, University of Alberta Edmonton, Alberta, Canada, T6G 2G2
| | - Joseph Cheramy
- Chemistry Department, University of Alberta Edmonton, Alberta, Canada, T6G 2G2
| | - Yunjie Xu
- Chemistry Department, University of Alberta Edmonton, Alberta, Canada, T6G 2G2
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20
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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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21
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Gogolashvili A, Lomsadze K, Chankvetadze L, Takaishvili N, Peluso P, Dallocchio R, Salgado A, Chankvetadze B. Separation of tetrahydrozoline enantiomers in capillary electrophoresis with cyclodextrin-type chiral selectors and investigation of chiral recognition mechanisms. J Chromatogr A 2021; 1643:462084. [PMID: 33789195 DOI: 10.1016/j.chroma.2021.462084] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 12/13/2022]
Abstract
The recognition power and affinity pattern of various cyclodextrins (CD) towards the enantiomers of tetrahydrozoline (THZ) were studied using capillary electrophoresis (CE). As expected, affinity of THZ enantiomers and selectivity of recognition towards CD derivatives was strongly dependent on the cavity size and substituent type and pattern on the CD rims. Not only were the affinity strength and selectivity of recognition affected by the size of the cavity and chemistry of the CDs but also the affinity pattern. Another interesting example of opposite affinity pattern of enantiomers towards α- and β-CD was observed here. In addition, opposite affinity pattern of THZ enantiomers was seen towards β-CD and its acetylated derivatives, while methylation of β-CD did not affect the affinity pattern of THZ enantiomers. In order to get more information about structural mechanisms of the multivariate dependences mentioned above, rotating frame Overhauser enhancement spectroscopy (ROESY) and computation techniques were used. Significant differences between the structure of THZ complexes with different CDs with both methods were encountered. Good correlations between experimentally determined and computed structure of complexes, as well as between computed complex stabilities and enantiomer migration order (EMO) in CE were observed.
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Affiliation(s)
- Ann Gogolashvili
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi 0179, Georgia
| | - Ketevan Lomsadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi 0179, Georgia; School of Science and Technology, The University of Georgia, 77a, M. Kostava Str., Tbilisi 0171, Georgia
| | - Lali Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi 0179, Georgia
| | - Nino Takaishvili
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi 0179, Georgia
| | - Paola Peluso
- Istituto di Chimica Biomolecolare ICB-CNR, Sede secondary a di Sassari, Traversa La Crucca 3, Regione Baldinca, Sassari, Li Punti 07100, Italy
| | - Roberto Dallocchio
- Istituto di Chimica Biomolecolare ICB-CNR, Sede secondary a di Sassari, Traversa La Crucca 3, Regione Baldinca, Sassari, Li Punti 07100, Italy
| | - Antonio Salgado
- NMR Spectroscopy Centre (CERMN), CAI Químicas, Faculty of Pharmacy, University of Alcalá, Alcalá de Henares, Madrid E-28805, Spain
| | - Bezhan Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, Tbilisi 0179, Georgia.
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22
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Kemper M, Engelage E, Merten C. Chirale molekulare Propeller basierend auf Triarylboran‐Ammoniak‐Addukten. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Michael Kemper
- Ruhr Universität Bochum Fakultät für Chemie und Biochemie, Organische Chemie II Universitätsstraße 150 44801 Bochum Deutschland
| | - Elric Engelage
- Ruhr Universität Bochum Fakultät für Chemie und Biochemie, Organische Chemie II Universitätsstraße 150 44801 Bochum Deutschland
| | - Christian Merten
- Ruhr Universität Bochum Fakultät für Chemie und Biochemie, Organische Chemie II Universitätsstraße 150 44801 Bochum Deutschland
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23
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Kemper M, Engelage E, Merten C. Chiral Molecular Propellers of Triarylborane Ammonia Adducts. Angew Chem Int Ed Engl 2021; 60:2958-2962. [PMID: 33197119 PMCID: PMC7898383 DOI: 10.1002/anie.202014130] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Indexed: 11/19/2022]
Abstract
Chiral molecular propeller conformations have been induced to various triaryl structures including trityl derivatives and triaryl boranes. For borane-amine adducts, such induced propeller chirality has not been reported yet due to the low energy barrier for racemization in common triarylboranes such as B(C6 H5 )3 or B(C6 F5 )3 . Herein, we demonstrate that point chirality in side chains of chiral triarylborane-ammonia adducts, which feature intramolecular hydrogen bonds in addition to the dative N→B bond, can efficiently be transferred to triarylborane propeller chirality. Employing X-ray crystallography and ECD/VCD spectroscopy for structural characterizations, we investigate three examples with different steric demands of the incorporated chiral alkoxy side groups. We elucidate the conformational preferences of the molecular propellers. Furthermore, we show that computationally predicted conformational preferences obtained for the isolated, only implicitly solvated molecules are actually opposite to the experimentally observed ones.
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Affiliation(s)
- Michael Kemper
- Ruhr Universität BochumFakultät für Chemie und Biochemie, Organische Chemie IIUniversitätsstrasse 15044801BochumGermany
| | - Elric Engelage
- Ruhr Universität BochumFakultät für Chemie und Biochemie, Organische Chemie IIUniversitätsstrasse 15044801BochumGermany
| | - Christian Merten
- Ruhr Universität BochumFakultät für Chemie und Biochemie, Organische Chemie IIUniversitätsstrasse 15044801BochumGermany
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24
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Giovannini T, Egidi F, Cappelli C. Theory and algorithms for chiroptical properties and spectroscopies of aqueous systems. Phys Chem Chem Phys 2020; 22:22864-22879. [PMID: 33043930 DOI: 10.1039/d0cp04027d] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Chiroptical properties and spectroscopies are valuable tools to study chiral molecules and assign absolute configurations. The spectra that result from chiroptical measurements may be very rich and complex, and hide much of their information content. For this reason, the interplay between experiments and calculations is especially useful, provided that all relevant physico-chemical interactions that are present in the experimental sample are accurately modelled. The inherent difficulty associated to the calculation of chiral signals of systems in aqueous solutions requires the development of specific tools, able to account for the peculiarities of water-solute interactions, and especially its ability to form hydrogen bonds. In this perspective we discuss a multiscale approach, which we have developed and challenged to model the most used chiroptical techniques.
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Affiliation(s)
- Tommaso Giovannini
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
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25
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Merten C. Recent Advances in the Application of Vibrational Circular Dichroism Spectroscopy for the Characterization of Asymmetric Catalysts. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000876] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Christian Merten
- Fakultät für Chemie und Biochemie Organische Chemie II Ruhr Universität Bochum Universitätsstraße 150 44801 Bochum Germany
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26
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Górecki M, Frelek J. A Critical Appraisal of Dimolybdenum Tetraacetate Application in Stereochemical Studies of vic-Diols by Circular Dichroism. JOURNAL OF NATURAL PRODUCTS 2020; 83:955-964. [PMID: 32148042 DOI: 10.1021/acs.jnatprod.9b00800] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This critical appraisal is intended for users of the dimolybdenum method, well-established in electronic circular dichroism (ECD) to determine the absolute configuration of vic-diols and, in particular, for experimental researchers not being experts in chiroptical methods. The main goal is to demonstrate how to avoid misleading and ambiguous conclusions resulting from the rigorous application of the helicity rule by limiting the analysis to the vic-diol unit alone. We particularly focused on multichromophoric systems, especially those that may interfere with the absorption of an in situ formed dimolybdenum tetraacetate-diol complex. In this context, examples are presented of vic-diols for which stereochemical assignment based solely on the helicity rule is ambiguous and does not necessarily lead to correct results. The motivation for choosing these examples was to demonstrate the impact of the structure of the substrate on the complexation process with the metal core and its selectivity. For each selected case, results obtained are analyzed in detail together with a discussion of existing restrictions and choice of a support method to increase the credibility of the conclusion. Based on seven both educational and challenging examples, it was shown that the dimolybdenum methodology can also be effectively applied to complex chromophoric systems, provided that other chiroptical methods and/or computational support verify obtained results.
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Affiliation(s)
- Marcin Górecki
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 Street, 01-224 Warsaw, Poland
| | - Jadwiga Frelek
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 Street, 01-224 Warsaw, Poland
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27
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Nafie LA. Vibrational optical activity: From discovery and development to future challenges. Chirality 2020; 32:667-692. [DOI: 10.1002/chir.23191] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 12/13/2022]
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28
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Golub TP, Merten C. Stereochemistry of the Reaction Intermediates of Prolinol Ether Catalyzed Reactions Characterized by Vibrational Circular Dichroism Spectroscopy. Chemistry 2020; 26:2349-2353. [PMID: 31854022 PMCID: PMC7065232 DOI: 10.1002/chem.201905614] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Indexed: 11/24/2022]
Abstract
Spectroscopic characterizations of key reaction intermediates are often considered the final confirmation of a reaction mechanism. This proof‐of‐principle study showcases the application of vibrational circular dichroism (VCD) spectroscopy for the characterization of in situ generated reaction intermediates using the key intermediates of enamine catalysis of Jørgensen–Hayashi‐type prolinol ether catalysts as model system. By comparison of experimental and computed spectra, the enamines are shown to preferentially adopt an anti‐conformation with E‐configured C=C bond. For the parent prolinol catalyst, the structure and stereochemistry of the oxazolidine side product is determined as well. This study thus demonstrates that VCD spectra can provide insights into structural preferences of organocatalysts that utilize a covalent activation mechanism. Thereby it outlines new fields of applications for VCD spectroscopy and finally adds the technique to the toolbox of physical organic chemistry for in‐depth mechanistic studies.
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Affiliation(s)
- Tino P. Golub
- Fakultät für Chemie und Biochemie, Organische Chemie IIRuhr Universität BochumUniversitätsstrasse 15044801BochumGermany
| | - Christian Merten
- Fakultät für Chemie und Biochemie, Organische Chemie IIRuhr Universität BochumUniversitätsstrasse 15044801BochumGermany
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29
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Rojo-Portillo T, Reyes-López E, Hernández-Huerta E, Quiroz-García B, Joseph-Nathan P, Sánchez-Castellanos M, Cuétara-Guadarrama F, Cuevas G. Is the VCD spectrum a fingerprint of the conformational population? The conformation of perezone in the spotlight. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127273] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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30
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Koenis MAJ, Visser O, Visscher L, Buma WJ, Nicu VP. GUI Implementation of VCDtools, A Program to Analyze Computed Vibrational Circular Dichroism Spectra. J Chem Inf Model 2020; 60:259-267. [PMID: 31830414 PMCID: PMC6988127 DOI: 10.1021/acs.jcim.9b00956] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
As
computing power increases, vibrational circular dichroism (VCD)
calculations on molecules of larger sizes and complexities become
possible. At the same time, the spectra resulting from these computations
become increasingly more cumbersome to analyze. Here, we describe
the GUI implementation into the Amsterdam Density Functional (ADF)
software package of VCDtools, a toolbox that provides a user-friendly
means to analyze VCD spectra. Key features are the use of the generalized
coupled oscillator analysis methods, as well as an easy visualization
of the atomic electric and magnetic transition dipole moments which
together provide detailed insight in the origin of the VCD intensity.
Using several prototypical examples we demonstrate the functionalities
of the program. In particular, we show how the spectra can be analyzed
to detect differences between theory and experiment arising from large-amplitude
motions or incorrect molecular structures and, most importantly, how
the program can be used to prevent incorrect enantiomeric assignments.
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Affiliation(s)
- Mark A J Koenis
- Van 't Hoff Institute for Molecular Sciences , University of Amsterdam , Science Park 904 , 1098 XH Amsterdam , The Netherlands
| | - Olivier Visser
- Software for Chemisty and Materials , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Lucas Visscher
- Amsterdam Center for Multiscale Modeling, Section Theoretical Chemistry, Faculty of Sciences , Vrije Universiteit Amsterdam , De Boelelaan 1083 , 1081 HV Amsterdam , The Netherlands
| | - Wybren J Buma
- Van 't Hoff Institute for Molecular Sciences , University of Amsterdam , Science Park 904 , 1098 XH Amsterdam , The Netherlands.,Institute for Molecules and Materials, FELIX Laboratory , Radboud University , Toernooiveld 7c , 6525 ED Nijmegen , The Netherlands
| | - Valentin P Nicu
- Department of Environmental Science, Physics, Physical Education and Sport , Lucian Blaga University of Sibiu , loan Ratiu Street, Number 7-9 , 550012 Sibiu , Romania
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31
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Sato H. A new horizon for vibrational circular dichroism spectroscopy: a challenge for supramolecular chirality. Phys Chem Chem Phys 2020; 22:7671-7679. [DOI: 10.1039/d0cp00713g] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The development of the solid state and time-step VCD methods opened a new horizon to reveal the mechanism of chirality amplification from microscopic to supramolecular scales.
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Affiliation(s)
- Hisako Sato
- Department of Chemistry
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
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32
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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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33
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Sato H, Takimoto K, Yoshida J, Yamagishi A. Vibrational circular dichroism towards asymmetric catalysis: chiral induction in substrates coordinated with copper( ii) ions. Phys Chem Chem Phys 2020; 22:24393-24398. [DOI: 10.1039/d0cp04827e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The VCD method was applied for searching the origin of chirality selection in the asymmetric catalysis by Cu(ii) complexes. When 1-phenyl-1,3-butanedionato was coordinated, it was transformed to a twisted chiral form under the steric control.
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Affiliation(s)
- Hisako Sato
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Kazuyoshi Takimoto
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Jun Yoshida
- Department of Chemistry
- Kitasato University
- Sagamihara 252-0329
- Japan
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34
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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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35
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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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36
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Strudwick BH, Koenis MAJ, Sanders HJ, Nicu VP, Woutersen S, Buma WJ. A Tunable, Fullerene-Based Molecular Amplifier for Vibrational Circular Dichroism. Chemistry 2019; 25:12560-12566. [PMID: 31273849 PMCID: PMC6790965 DOI: 10.1002/chem.201902190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/29/2019] [Indexed: 01/03/2023]
Abstract
Vibrational circular dichroism (VCD) studies are reported on a chiral compound in which a fullerene C60 moiety is used as an electron acceptor and local VCD amplifier for an alanine-based peptide chain. Four redox states are investigated in this study, of which three are reduced species that possess low-lying electronic states as confirmed by UV/Vis spectroelectrochemistry. VCD measurements in combination with (TD)DFT calculations are used to investigate (i) how the low-lying electronic states of the reduced species modulate the amplification of VCD signals, (ii) how this amplification depends on the distance between oscillator and amplifier, and (iii) how the spatial extent of the amplifier influences amplification. These results pave the way for further development of tailored molecular VCD amplifiers.
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Affiliation(s)
- Benjamin H. Strudwick
- Molecular Photonics Group, Van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
| | - Mark A. J. Koenis
- Molecular Photonics Group, Van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
| | - Hans J. Sanders
- Molecular Photonics Group, Van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
| | - Valentin P. Nicu
- Department of Environmental Science, Physics, Physical Education and SportLucian Blaga University of Sibiuloan Ratiu Street, Nr. 7-9550012SibiuRomania
| | - Sander Woutersen
- Molecular Photonics Group, Van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
| | - Wybren Jan Buma
- Molecular Photonics Group, Van't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamThe Netherlands
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37
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Miura T, Nakamuro T, Nagata Y, Moriyama D, Stewart SG, Murakami M. Asymmetric Synthesis and Stereochemical Assignment of 12C/ 13C Isotopomers. J Am Chem Soc 2019; 141:13341-13345. [PMID: 31408332 DOI: 10.1021/jacs.9b07181] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A synthesis of chiral hydrocarbons having C1 axis and C3 symmetry, which owe their chirality due to asymmetrical distribution of 12C/13C isotopes, is reported. Their absolute configurations assigned using the vibrational circular dichroism technique conform with those deduced from the absolute configurations of the parent α-formyl cyclopropanes.
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Affiliation(s)
- Tomoya Miura
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
| | - Takayuki Nakamuro
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
| | - Yuuya Nagata
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
| | - Daisuke Moriyama
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
| | - Scott G Stewart
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
| | - Masahiro Murakami
- Department of Synthetic Chemistry and Biological Chemistry , Kyoto University , Katsura, Kyoto 615-8510 , Japan
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38
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Merten C, Golub TP, Kreienborg NM. Absolute Configurations of Synthetic Molecular Scaffolds from Vibrational CD Spectroscopy. J Org Chem 2019; 84:8797-8814. [PMID: 31046276 DOI: 10.1021/acs.joc.9b00466] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Vibrational circular dichroism (VCD) spectroscopy is one of the most powerful techniques for the determination of absolute configurations (AC), as it does not require any specific UV/vis chromophores, no chemical derivatization, and no growth of suitable crystals. In the past decade, it has become increasingly recognized by chemists from various fields of synthetic chemistry such as total synthesis and drug discovery as well as from developers of asymmetric catalysts. This perspective article gives an overview about the most important experimental aspects of a VCD-based AC determination and explains the theoretical analysis. The comparison of experimental and computational spectra that leads to the final conclusion about the AC of the target molecules is described. In addition, the review summarizes unique VCD studies carried out in the period 2008-2018 that focus on the determination of unknown ACs of new compounds, which were obtained in its enantiopure form either through direct asymmetric synthesis or chiral chromatography.
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Affiliation(s)
- Christian Merten
- Ruhr Universität Bochum , Organische Chemie II , Universitätsstraße 150 , 44780 Bochum , Germany
| | - Tino P Golub
- Ruhr Universität Bochum , Organische Chemie II , Universitätsstraße 150 , 44780 Bochum , Germany
| | - Nora M Kreienborg
- Ruhr Universität Bochum , Organische Chemie II , Universitätsstraße 150 , 44780 Bochum , Germany
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39
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Kreienborg NM, Merten C. How to treat C-F stretching vibrations? A vibrational CD study on chiral fluorinated molecules. Phys Chem Chem Phys 2019; 21:3506-3511. [PMID: 29863202 DOI: 10.1039/c8cp02395f] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The analysis of vibrational circular dichroism and infrared spectra typically requires the prediction of spectra on the density functional theory level. In particular for absolute configuration determinations, for which the comparison between experiment and theory is often supported by similarity analysis algorithms, it is important that frequencies, relative band intensities and VCD signs are predicted correctly. Due to the poor prediction of harmonic frequencies, carbon-fluorine stretching vibrations are often strongly misplaced by common hybrid functionals such as B3LYP. Herein we show that the M06-2X functional provides harmonic C-F stretching frequencies with an accuracy sufficient for a reliable spectra analysis. We briefly discuss the origin of this exceptional performance and show that it is likely to be related to a cancellation of errors.
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Affiliation(s)
- Nora M Kreienborg
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie 2, Universitätstraße 150, 44801 Bochum, Germany.
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40
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Górecki M, Zullo V, Iuliano A, Pescitelli G. On the Absolute Stereochemistry of Tolterodine: A Circular Dichroism Study. Pharmaceuticals (Basel) 2019; 12:ph12010021. [PMID: 30691175 PMCID: PMC6469158 DOI: 10.3390/ph12010021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/18/2019] [Accepted: 01/22/2019] [Indexed: 02/06/2023] Open
Abstract
Tolterodine (1) is a potent muscarinic receptor antagonist used in the treatment of overactive urinary bladder (OAB) syndrome. Tolterodine is chiral and it was patented, and is currently marketed, as the l-tartrate salt of the (R)-enantiomer. However, the existing literature does not offer an ultimate proof of a stereoselective mode of action of 1. A second open stereochemical issue concerns the absolute configuration (AC) of 1. Neither the original patents nor subsequent studies have established the AC of 1 in an unambiguous way, although the AC of the l-tartrate salt of 1 was assigned by X-ray diffractometry. Finally, neither electronic nor vibrational circular dichroism (ECD and VCD) spectra of 1 are reported so far. We performed a thorough ECD/VCD study of 1 in different solvents and at variable temperatures. Solvent and temperature dependence highlighted the existence of moderate flexibility which was confirmed by molecular modelling. ECD calculations with time-dependent density functional theory (TDDFT) accurately reproduced the experimental spectra and allowed us to confirm the AC of 1 in an independent way.
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Affiliation(s)
- Marcin Górecki
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 St., 01-224 Warsaw, Poland.
| | - Valerio Zullo
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| | - Anna Iuliano
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
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41
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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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42
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Perera AS, Cheramy J, Poopari MR, Xu Y. Aggregation of lactic acid in cold rare-gas matrices and the link to solution: a matrix isolation-vibrational circular dichroism study. Phys Chem Chem Phys 2019; 21:3574-3584. [DOI: 10.1039/c8cp04748k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Crucial insight into lactic acid self-aggregation in solution is obtained by following its unique VCD spectral features in cold matrices.
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Affiliation(s)
| | - Joseph Cheramy
- Chemistry Department
- The University of Alberta
- Edmonton
- Canada
| | | | - Yunjie Xu
- Chemistry Department
- The University of Alberta
- Edmonton
- Canada
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43
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Patti A, Pedotti S, Mazzeo G, Longhi G, Abbate S, Paoloni L, Bloino J, Rampino S, Barone V. Ferrocenes with simple chiral substituents: an in-depth theoretical and experimental VCD and ECD study. Phys Chem Chem Phys 2019; 21:9419-9432. [DOI: 10.1039/c9cp00437h] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ferrocenes bearing chiral pendants are investigated through VCD and ECD. The VCD spectra are best interpreted by GVPT2-anharmonic DFT calculations. Diagnostic bands related to the absolute configuration of the title compounds are found in both kinds of spectra.
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Affiliation(s)
- Angela Patti
- Institute of Biomolecular Chemistry – CNR
- 95126 Catania
- Italy
| | - Sonia Pedotti
- Institute of Biomolecular Chemistry – CNR
- 95126 Catania
- Italy
| | - Giuseppe Mazzeo
- Dipartimento di Medicina Molecolare e Traslazionale (DMMT)
- Università di Brescia
- 25123 Brescia
- Italy
| | - Giovanna Longhi
- Dipartimento di Medicina Molecolare e Traslazionale (DMMT)
- Università di Brescia
- 25123 Brescia
- Italy
| | - Sergio Abbate
- Dipartimento di Medicina Molecolare e Traslazionale (DMMT)
- Università di Brescia
- 25123 Brescia
- Italy
| | | | - Julien Bloino
- Scuola Normale Superiore
- I-56126 Pisa
- Italy
- Consiglio Nazionale delle Ricerche
- Istituto di Chimica dei Composti OrganoMetallici (CNR-ICCOM) Area della Ricerca CNR
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44
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Kreienborg NM, Bloino J, Osowski T, Pollok CH, Merten C. The vibrational CD spectra of propylene oxide in liquid xenon: a proof-of-principle CryoVCD study that challenges theory. Phys Chem Chem Phys 2019; 21:6582-6587. [DOI: 10.1039/c9cp00537d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Propylene oxide (PO) is the ideal candidate to benchmark both new experimental and theoretical approaches. Herein it is used to demonstrate the feasibility of measurements of VCD spectra in liquid rare gases (CryoVCD) and to test recent theoretical developments in the prediction of anharmonic IR and VCD spectra.
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Affiliation(s)
- Nora M. Kreienborg
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | - Julien Bloino
- Scuola Normale Superiore
- Piazza dei Cavalieri 7
- 56126 Pisa
- Italy
| | - Tobias Osowski
- Ruhr-Universität Bochum
- Fakultät für Chemie und Biochemie
- Organische Chemie II
- 44801 Bochum
- Germany
| | - Corina H. Pollok
- 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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45
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Ghidinelli S, Abbate S, Boiadjiev SE, Lightner DA, Longhi G. l-Stercobilin-HCl and d-Urobilin-HCl. Analysis of Their Chiroptical and Conformational Properties by VCD, ECD, and CPL Experiments and MD and DFT Calculations. J Phys Chem B 2018; 122:12351-12362. [DOI: 10.1021/acs.jpcb.8b07954] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Simone Ghidinelli
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Sergio Abbate
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Stefan E. Boiadjiev
- Department of Chemistry and Biochemistry, Medical University-Pleven, 1 St. Kl. Ohridski Str., 5800 Pleven, Bulgaria
| | - David A. Lightner
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, 89557-0020 Nevada, United States
| | - Giovanna Longhi
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy
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46
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Kreienborg NM, Merten C. How Do Substrates Bind to a Bifunctional Thiourea Catalyst? A Vibrational CD Study on Carboxylic Acid Binding. Chemistry 2018; 24:17948-17954. [PMID: 30230065 DOI: 10.1002/chem.201804230] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Indexed: 01/14/2023]
Abstract
Knowledge about the active conformation of an asymmetric catalyst is highly valuable in order to understand its stereoinductive power, but spectroscopic access to these structures is often limited. For the example of Takemoto's bifunctional thiourea, we demonstrate the capability of VCD spectroscopy to characterize the conformational preferences of the catalyst with and without having a reactant bound to it. In particular we show that the binding orientation of carboxylic acids can easily be derived from a computationally guided analysis of the spectra. Moreover, we identify characteristic marker bands, which are only visible in the VCD spectra of the catalyst/acid mixtures but not in the corresponding IR spectra. Lastly, we also discuss the problem that the popular DFT functional M06-2X, which we found to perform exceptionally well in the calculations of vibrational frequencies for fluorinated molecules, predicts incorrect structures of the molecular clusters. We relate this poor performance in predicting the structure of the binding topologies to an overestimation of dispersive CH-π and π-π interactions, which occur due to a neglect of the solvent molecules in the clusters. VCD spectroscopy is thus shown to be a powerful tool to identify and subsequently correct such mispredictions of solution-phase structures.
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Affiliation(s)
- Nora M Kreienborg
- Ruhr-Universität Bochum, Fakultät für Chemie, Lehrstuhl für Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany
| | - Christian Merten
- Ruhr-Universität Bochum, Fakultät für Chemie, Lehrstuhl für Organische Chemie II, Universitätsstraße 150, 44801, Bochum, Germany
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47
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Sato H, Watanabe K, Koshoubu J. In-Situ Monitoring of Sol-Gel Transition by Temperature-dependent VCD Method: Signal Enhancement Induced by Gelation. CHEM LETT 2018. [DOI: 10.1246/cl.180729] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hisako Sato
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Keisuke Watanabe
- JASCO Corporation, 2967-5 Ishikawa-machi, Hachioji, Tokyo 192-8537, Japan
| | - Jun Koshoubu
- JASCO Corporation, 2967-5 Ishikawa-machi, Hachioji, Tokyo 192-8537, Japan
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48
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Jähnigen S, Scherrer A, Vuilleumier R, Sebastiani D. VCD‐Verstärkung durch chirale Packungseffekte in molekularen Kristallen. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sascha Jähnigen
- Martin-Luther-Universität Halle-Wittenberg Institut für Chemie von-Danckelmann-Platz 4 Halle 06120 Deutschland
| | - Arne Scherrer
- Martin-Luther-Universität Halle-Wittenberg Institut für Chemie von-Danckelmann-Platz 4 Halle 06120 Deutschland
| | - Rodolphe Vuilleumier
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS 75005 Paris Frankreich
| | - Daniel Sebastiani
- Martin-Luther-Universität Halle-Wittenberg Institut für Chemie von-Danckelmann-Platz 4 Halle 06120 Deutschland
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49
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Jähnigen S, Scherrer A, Vuilleumier R, Sebastiani D. Chiral Crystal Packing Induces Enhancement of Vibrational Circular Dichroism. Angew Chem Int Ed Engl 2018; 57:13344-13348. [DOI: 10.1002/anie.201805671] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/25/2018] [Indexed: 01/15/2023]
Affiliation(s)
- Sascha Jähnigen
- Martin-Luther-Universität Halle-WittenbergInstitut für Chemie von-Danckelmann-Platz 4 Halle 06120 Germany
| | - Arne Scherrer
- Martin-Luther-Universität Halle-WittenbergInstitut für Chemie von-Danckelmann-Platz 4 Halle 06120 Germany
| | - Rodolphe Vuilleumier
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS 75005 Paris France
| | - Daniel Sebastiani
- Martin-Luther-Universität Halle-WittenbergInstitut für Chemie von-Danckelmann-Platz 4 Halle 06120 Germany
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50
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Rode JE, Górecki M, Witkowski S, Frelek J. Solvation of 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol revealed by circular dichroism: a case of chromane helicity rule breaking. Phys Chem Chem Phys 2018; 20:22525-22536. [PMID: 30140796 DOI: 10.1039/c8cp02491j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The primary goal of this work is to clarify why 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol {(S)-TMChM} deviates from the chromane helicity rule under solvent change. The rule, applicable to determining the absolute configuration of molecules containing the chromane chromophore, binds the sign of the 1Lb Cotton effect (CE) with the helicity of the dihydropyran ring. In case of TMChM, however, this CE exhibits extreme solvent dependence: it is negative in non-coordinating solvents and positive in coordinating ones, irrespective of the helicity of the heterocyclic ring. TD-DFT calculations using PCM and hybrid solvation models were performed to explain origin of this phenomenon. It turned out that the 1Lb CE sign directly depends on the position of the phenolic OH group at carbon atom C6 (OHC6). In the absence of interactions with solvents (as in CCl4 or nC6H14) or when a solvent plays proton donor role (as in CHCl3), the OHC6 lies in the phenyl plane and the 1Lb CE sign follows the P/M helicity rule. In contrast, in proton acceptor solvents, like DMSO, CH3OH or CH3CN, the OHC6 group is deflected from the phenyl plane, and the 1Lb CE sign of individual (S)-TMChM conformers depends on the sector in which the OHC6 is located. Thus, in solution, the 1Lb CE sign is an average over different orientations of the OHC6 group and can be positive (as in DMSO and CH3OH) or negative (as in CH3CN) which means that it does not follow the chromane helicity rule. The impact of OHC6 on the 1Lb CE sign and thus the conclusions for the stereochemistry of chromans are demonstrated here for the first time. Additionally, a comparison of experimental and simulated ECD spectra, supported by VCD data, allowed to determine the geometry of intermolecular clusters formed in different solvents.
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Affiliation(s)
- Joanna E Rode
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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