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Kartouzian A, Cameron RP. Unlocking the hidden dimension: power of chirality in scientific exploration. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2024; 382:20230321. [PMID: 39246075 DOI: 10.1098/rsta.2023.0321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/04/2024] [Accepted: 04/18/2024] [Indexed: 09/10/2024]
Abstract
In the boundless landscape of scientific exploration, there exists a hidden, yet easily accessible, dimension that has often not only intrigued and puzzled researchers but also provided the key. This dimension is chirality, the property that describes the handedness of objects. The influence of chirality extends across diverse fields of study from the parity violation in electroweak interactions to the extremely large macroscopic systems such as galaxies. In this opinion piece, we will delve into the power of chirality in scientific exploration by examining some examples that, at different scales, demonstrate its role as a key to a better understanding of our world. Our goal is to incite researchers from all fields to seek, implement and utilize chirality in their research. Going this extra mile might be more rewarding than it seems at first glance, in particular with regard to the increasing demand for new functional materials in response to the contemporary scientific and technological challenges we are facing. This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.
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Affiliation(s)
- Aras Kartouzian
- Department of Chemistry and Catalysis Research Center, TUM School of Natural Sciences, Technical University of Munich, Lichtenbergstr. 4 , Garching bei München 85748, Germany
| | - Robert P Cameron
- SUPA and Department of Physics, University of Strathclyde , Glasgow G4 0NG, UK
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Jeong C, Yun J, Heo J, Kim NJ. Anisotropic circular dichroism of jet-cooled chiral molecules. Phys Chem Chem Phys 2023; 25:22644-22649. [PMID: 37591819 DOI: 10.1039/d3cp03074a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Anisotropic circular dichroism (CD) refers to the CD of oriented molecules, which varies with the direction of light propagation toward the molecules. Thus, anisotropic CD spectroscopy has been used to investigate the orientations of molecules in anisotropic media such as liquid crystals and thin films. However, it is unclear whether anisotropic CD results from isolated chromophores or their intermolecular interactions with other atoms or molecules that form anisotropically aligned structures. Herein, anisotropic CD of isolated chiral molecules was observed for the first time. The resonant two-photon ionization CD spectra of jet-cooled pseudoephedrine and styrene oxide indicated a difference between the CD values of the P/R and Q branches of the origin bands of the S0-S1 transition. This difference may have resulted from the anisotropic CD phenomena of these molecules, which are oriented via photoselection. Although jet-cooled molecules may have nearly random orientations, those excited to the P/R or Q branch become oriented because the transition probability to these branches depends on the molecular orientation relative to the direction of light propagation. These results demonstrate that the CD spectra of cold, isolated molecules, such as those in an interstellar medium, may exhibit anisotropic CD values.
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Affiliation(s)
- Changseop Jeong
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Jiyeon Yun
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Jiyoung Heo
- Department of Green Chemical Engineering, Sangmyung University, Chungnam 31066, Korea.
| | - Nam Joon Kim
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
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3
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Jeong C, Eun HJ, Yun J, Kim NJ. Dual-Beam Circular Dichroism Spectroscopy of Jet-Cooled Chiral Molecules. J Phys Chem A 2022; 126:4295-4299. [PMID: 35758322 DOI: 10.1021/acs.jpca.2c02745] [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
Circular dichroism (CD) spectroscopy of jet-cooled molecules provides conformation-specific CD spectra. However, its widespread utilization has been limited by the weak CD effects and the low density of gas-phase molecules. Here, we developed a dual-beam method to improve the sensitivity and accuracy of gas-phase CD measurements. Circularly and linearly polarized pulses were generated from a single laser pulse and used to irradiate a single molecular-beam pulse to produce two ion peaks. The ion peaks induced by linearly polarized pulses were subtracted from those induced by circularly polarized pulses to correct the CD values for the pulse-to-pulse fluctuations in laser power and gas density. The resonant two-photon ionization CD spectrum of (1R,2R)-(-)-pseudoephedrine revealed that the standard deviations of CD values measured using the dual-beam method were three times lower than those measured using a single-beam method. The dual-beam method provides an effective, accurate, and easy-to-use tool to obtain gas-phase CD spectra.
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Affiliation(s)
- Changseop Jeong
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Han Jun Eun
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Jiyeon Yun
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
| | - Nam Joon Kim
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea
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4
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Lehmann CS, Botros D, Weitzel KM. Coincident measurement of photo-ion circular dichroism and photo-electron circular dichroism on 1-Phenylethylamine. Phys Chem Chem Phys 2022; 24:15904-15911. [DOI: 10.1039/d2cp01418a] [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
Here we report the coincident measurement of the PICD and PECD effect in 1-Phenylethylamine upon multiphoton ionisation. Photo-ion circular dichroism (PICD) and photo-electron circular dichroism (PECD) are both methods to...
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Lee HG, Ranecky ST, Vasudevan S, Ladda N, Rosen T, Das S, Ghosh J, Braun H, Reich DM, Senftleben A, Baumert T. Pulse length dependence of photoelectron circular dichroism. Phys Chem Chem Phys 2022; 24:27483-27494. [DOI: 10.1039/d2cp03202c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We investigated photoelectron circular dichroism (PECD) using pulses with various durations. From the experiment with fenchone, we found constancy of the PECD over a wide range of pulse durations and estimated lifetimes of internal conversions.
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Affiliation(s)
- Han-gyeol Lee
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Simon T. Ranecky
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Sudheendran Vasudevan
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Nicolas Ladda
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Tonio Rosen
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Sagnik Das
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Jayanta Ghosh
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Hendrike Braun
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Daniel M. Reich
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Arne Senftleben
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Thomas Baumert
- Institut für Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
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Yoo IT, Eun HJ, Min A, Jeon CW, Jeong J, Heo J, Kim NJ. Ultraviolet photodissociation circular dichroism spectroscopy of protonated L-phenylalanyl-L-alanine in a cryogenic ion trap. Phys Chem Chem Phys 2021; 23:24180-24186. [PMID: 34676382 DOI: 10.1039/d1cp04030h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We obtained ultraviolet photodissociation (UVPD) circular dichroism (CD) spectra of protonated L-phenylalanyl-L-alanine (L-H+PheAla) near the origin band of the S0-S1 transition using cryogenic ion spectroscopy. Infrared (IR) ion-dip, IR-UV hole burning (HB) and UV-UV HB spectra showed that L-H+PheAla existed as two different conformers in a cryogenic ion trap, and they had nearly identical peptide backbones but different conformations in the Phe side chain. The UVPD CD spectra revealed that the two conformers had opposite CD signs and significantly different CD magnitudes from each other. These results demonstrate that the CD value of L-H+PheAla near the origin band is strongly influenced by the conformation of the Phe side chain.
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Affiliation(s)
- Il Tae Yoo
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Han Jun Eun
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Ahreum Min
- Department of Chemistry (BK21 +) and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Korea
| | - Chang Wook Jeon
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Jinho Jeong
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
| | - Jiyoung Heo
- Department of Green Chemical Engineering, Sangmyung University, Chungnam 31066, Korea
| | - Nam Joon Kim
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea.
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Eun HJ, Min A, Jeon CW, Yoo IT, Heo J, Kim NJ. Chiral and Isomeric Discrimination of Chiral Molecular Ions by Cold Ion Circular Dichroism Spectroscopy. J Phys Chem Lett 2020; 11:4367-4371. [PMID: 32396359 DOI: 10.1021/acs.jpclett.0c01081] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Circular dichroism (CD) spectra contain information about absolute configurations and conformations of chiral compounds. However, extracting this information from CD spectra in solution is challenging, because the spectra exhibit only the averaged CD values of all different conformers. CD spectroscopy of jet-cooled molecules can provide conformation-specific CD spectra, but its application to biomolecules has been limited due to the difficulty of their production in the gas phase. Here, we obtained the first CD spectra of chiral molecular ions produced by electrospray ionization (ESI) using cold ion CD spectroscopy. Protonated l- or d-phenylalanine ions produced by ESI were stored in a cold quadrupole ion trap and irradiated by multiple laser pulses with left or right circular polarization. The CD spectra exhibited well-resolved CD bands of two conformers, whose signs were opposite to each other. This study will broaden the scope of conformation-resolved CD spectroscopy to large molecular ions without size limitations.
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Affiliation(s)
- Han Jun Eun
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea
| | - Ahreum Min
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea
| | - Chang Wook Jeon
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea
| | - Il Tae Yoo
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea
| | - Jiyoung Heo
- Department of Green Chemical Engineering, Sangmyung University, Chungnam 31066, Korea
| | - Nam Joon Kim
- Department of Chemistry, Chungbuk National University, Chungbuk 28644, Korea
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Huang L, Gao Z, Yin X, He Q, Pan Y. Exploration of disaccharide as reference towards chiral recognition by the kinetic method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8764. [PMID: 32079037 DOI: 10.1002/rcm.8764] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/17/2020] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
RATIONALE A potential use of disaccharides was found as reference compounds in the kinetic method for chiral recognition and enantiomeric quantification. METHODS The experimental procedure consists of three steps: (1) mixing a metal salt, an analyte and a disaccharide at a molar ratio of 1:2:2 with an analyte concentration of 20 μM; (2) introducing the mixture into an electrospray ionization (ESI) mass spectrometry source; (3) isolating the ion [MII (ref*)2 (A) - H]+ and subjecting it to dissociation. Then through the relative ratio of two product ions combined with the kinetic method, chiral recognition and enantiomeric quantification can be achieved. RESULTS The method was verified with good chiral recognition for ten chiral amino acids and three chiral drugs. Among the ten amino acids, Tyr was observed to show best chiral selectivity (Rchiral = 1.62) and good linearity with the correlation coefficient R2 = 0.9991 for the quantitation of the enantiomeric excess (ee) of D-Tyr. Among the tested chiral drugs, naproxen showed best chiral selectivity with Rchiral = 1.56 and good linearity with the correlation coefficient R2 = 0.9997 for the quantitation of the ee of R-naproxen. CONCLUSIONS This established approach proves that a disaccharide can serve as a reference compound for chiral recognition using the kinetic method.
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Affiliation(s)
- Lili Huang
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Zhan Gao
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Xinchi Yin
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Quan He
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - Yuanjiang Pan
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
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Poline M, Rebrov O, Larsson M, Zhaunerchyk V. Theoretical studies of infrared signatures of proton-bound amino acid dimers with homochiral and heterochiral moieties. Chirality 2020; 32:359-369. [PMID: 31943359 DOI: 10.1002/chir.23165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/14/2019] [Accepted: 12/16/2019] [Indexed: 01/23/2023]
Abstract
Proton-bound homochiral and heterochiral dimers, X-H+ -X, of five amino acids (X = Ser, Ala, Thr, Phe, and Arg) are investigated theoretically using quantum chemical density functional theory (DFT) calculations and molecular dynamics simulations with the aim to unveil diastereomer-specific mid-infrared (mid-IR) absorption bands in the spectral range of 1000 to 1800 cm-1 . The theoretical calculations performed in this work imply that all systems, except Ala2 H+ , have distinct mid-IR absorption bands in homochiral and heterochiral configurations, which make them appropriate systems to be studied experimentally with mid-IR spectroscopy. We show that intermolecular interaction with the side chain, in the form of hydrogen bonding or cation-π interaction, is necessary for chiral effects to be present in the mid-IR spectra of proton-bound dimers of amino acids. We also report new conformers for Ala2 H+ , Thr2 H+ , Phe2 H+ , and Arg2 H+ , which were not found in earlier studies of these dimers.
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Affiliation(s)
- Mathias Poline
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Oleksii Rebrov
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Mats Larsson
- Department of Physics, Stockholm University, Stockholm, Sweden
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10
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Lehmann CS, Weitzel KM. Coincident measurement of photo-ion circular dichroism and photo-electron circular dichroism. Phys Chem Chem Phys 2020; 22:13707-13712. [DOI: 10.1039/d0cp01376e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photo-ion circular dichroism (PICD) and photo-electron circular dichroism (PECD) have been measured for the first time simultaneously in a coincidence experiment detecting the chirality of R- and S-Methyloxirane.
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11
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Mortaheb F, Oberhofer K, Riemensberger J, Ristow F, Kienberger R, Heiz U, Iglev H, Kartouzian A. Enantiospecific Desorption Triggered by Circularly Polarized Light. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Farinaz Mortaheb
- Catalysis Research Center and Chemistry Department Chair of Physical Chemistry Technische Universität München Lichtenbergstr. 4 85748 Garching Germany
| | - Katrin Oberhofer
- Physik-Department E11 Technische Universität München James-Franck-Str. 1 85748 Garching Germany
| | - Johann Riemensberger
- Physik-Department E11 Technische Universität München James-Franck-Str. 1 85748 Garching Germany
| | - Florian Ristow
- Physik-Department E11 Technische Universität München James-Franck-Str. 1 85748 Garching Germany
| | - Reinhard Kienberger
- Physik-Department E11 Technische Universität München James-Franck-Str. 1 85748 Garching Germany
| | - Ulrich Heiz
- Catalysis Research Center and Chemistry Department Chair of Physical Chemistry Technische Universität München Lichtenbergstr. 4 85748 Garching Germany
| | - Hristo Iglev
- Physik-Department E11 Technische Universität München James-Franck-Str. 1 85748 Garching Germany
| | - Aras Kartouzian
- Catalysis Research Center and Chemistry Department Chair of Physical Chemistry Technische Universität München Lichtenbergstr. 4 85748 Garching Germany
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Mortaheb F, Oberhofer K, Riemensberger J, Ristow F, Kienberger R, Heiz U, Iglev H, Kartouzian A. Enantiospecific Desorption Triggered by Circularly Polarized Light. Angew Chem Int Ed Engl 2019; 58:15685-15689. [PMID: 31393661 PMCID: PMC6851867 DOI: 10.1002/anie.201906630] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/18/2019] [Indexed: 11/09/2022]
Abstract
The interest in enantioseparation and enantiopurification of chiral molecules has been drastically increasing over the past decades, since these are important steps in various disciplines such as pharmaceutical industry, asymmetric catalysis, and chiral sensing. By exposing racemic samples of BINOL (1,1′‐bi‐2‐naphthol) coated onto achiral glass substrates to circularly polarized light, we unambiguously demonstrate that by controlling the handedness of circularly polarized light, preferential desorption of enantiomers can be achieved. There are currently no mechanisms known that would describe this phenomenon. Our observation together with a simplified phenomenological model suggests that the process of laser desorption needs to be further developed and the contribution of quantum mechanical processes should be revisited to account for these data. Asymmetric laser desorption provides us with a contamination‐free technique for the enantioenrichment of chiral compounds.
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Affiliation(s)
- Farinaz Mortaheb
- Catalysis Research Center and Chemistry Department, Chair of Physical Chemistry, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Katrin Oberhofer
- Physik-Department E11, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
| | - Johann Riemensberger
- Physik-Department E11, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
| | - Florian Ristow
- Physik-Department E11, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
| | - Reinhard Kienberger
- Physik-Department E11, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
| | - Ulrich Heiz
- Catalysis Research Center and Chemistry Department, Chair of Physical Chemistry, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Hristo Iglev
- Physik-Department E11, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany
| | - Aras Kartouzian
- Catalysis Research Center and Chemistry Department, Chair of Physical Chemistry, Technische Universität München, Lichtenbergstr. 4, 85748, Garching, Germany
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Kartouzian A. Spectroscopy for model heterogeneous asymmetric catalysis. Chirality 2019; 31:641-657. [PMID: 31318108 DOI: 10.1002/chir.23113] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/02/2019] [Indexed: 12/31/2022]
Abstract
Heterogeneous catalysis has vastly benefited from investigations performed on model systems under well-controlled conditions. The application of most of the techniques utilized for such studies is not feasible for asymmetric reactions as enantiomers possess identical physical and chemical properties unless while interacting with polarized light and other chiral entities. A thorough investigation of a heterogeneous asymmetric catalytic process should include probing the catalyst prior to, during, and after the reaction as well as the analysis of reaction products to evaluate the achieved enantiomeric excess. I present recent studies that demonstrate the strength of chiroptical spectroscopic methods to tackle the challenges in investigating model heterogeneous asymmetric catalysis covering all the abovementioned aspects.
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Affiliation(s)
- Aras Kartouzian
- Lehrstuhl für physikalische Chemie, Catalysis Research Center, Technische Universität München, Garching bei München, Germany
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Hanley L, Wickramasinghe R, Yung YP. Laser Desorption Combined with Laser Postionization for Mass Spectrometry. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2019; 12:225-245. [PMID: 30786215 DOI: 10.1146/annurev-anchem-061318-115447] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lasers with pulse lengths from nanoseconds to femtoseconds and wavelengths from the mid-infrared to extreme ultraviolet (UV) have been used for desorption or ablation in mass spectrometry. Such laser sampling can often benefit from the addition of a second laser for postionization of neutrals. The advantages offered by laser postionization include the ability to forego matrix application, high lateral resolution, decoupling of ionization from desorption, improved analysis of electrically insulating samples, and potential for high sensitivity and depth profiling while minimizing differential detection. A description of postionization by vacuum UV radiation is followed by a consideration of multiphoton, short pulse, and other postionization strategies. The impacts of laser pulse length and wavelength are considered for laser desorption or laser ablation at low pressures. Atomic and molecular analysis via direct laser desorption/ionization using near-infrared ultrashort pulses is described. Finally, the postionization of clusters, the role of gaseous collisions, sampling at ambient pressure, atmospheric pressure photoionization, and the addition of UV postionization to MALDI are considered.
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Affiliation(s)
- Luke Hanley
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA;
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15
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Kastner A, Ring T, Braun H, Senftleben A, Baumert T. Observation of Photoelectron Circular Dichroism Using a Nanosecond Laser. Chemphyschem 2019; 20:1416-1419. [PMID: 30972931 DOI: 10.1002/cphc.201900289] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/02/2019] [Indexed: 11/09/2022]
Abstract
Photoelectron circular dichroism (PECD) is a fascinating phenomenon both from a fundamental science aspect but also due to its emerging role as a highly sensitive analytic tool for chiral recognition in the gas phase. PECD has been studied with single-photon as well as multi-photon ionization. The latter has been investigated in the short pulse limit with femtosecond laser pulses, where ionization can be thought of as an instantaneous process. In this contribution, we demonstrate that multi-photon PECD still can be observed when using an ultra-violet nanosecond pulse to ionize chiral showcase fenchone molecules. Compared to femtosecond ionization, the magnitude of PECD is similar, but the lifetime of intermediate molecular states imprints itself in the photoelectron spectra. Being able to use an industrial nanosecond laser to investigate PECD furthermore reduces the technical requirements to apply PECD in analytical chemistry.
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Affiliation(s)
- Alexander Kastner
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Tom Ring
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Hendrike Braun
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Arne Senftleben
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Thomas Baumert
- Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
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16
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Wollschläger JM, Simon K, Gaedke M, Schalley CA. Ion mobility and gas phase H/D exchange: revealing the importance of a single hydrogen bond for the chiral recognition of crown ether ammonium complexes. Chem Commun (Camb) 2018; 54:4967-4970. [PMID: 29701736 DOI: 10.1039/c8cc01671b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Two new BINOL-based chiral crown ether/ammonium complexes are studied by travelling-wave ion-mobility spectrometry. Homo- and heterochiral crown ether/ammonium complexes differ in their collision cross sections, and these differences go along with changes in hydrogen bonding as revealed by gas phase H/D-exchange experiments. Applications for the determination of enantiomeric excess are discussed.
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Affiliation(s)
- Jan M Wollschläger
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
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17
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Santoro F, Mortaheb F, Lepelmeier J, Boesl U, Heiz U, Kartouzian A. High-Resolution Absorption and Electronic Circular Dichroism Spectra of (R)-(+)-1-Phenylethanol. Confident Interpretation Based on the Synergy between Experiments and Computations. Chemphyschem 2018; 19:715-723. [PMID: 29239510 DOI: 10.1002/cphc.201701254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 12/13/2017] [Indexed: 11/09/2022]
Abstract
Using density functional theory and its time-dependent extension for excited states, the S0 →S1 high-resolution vibronic absorption and electronic circular dichroism spectra of (R)-(+)-1-phenylethanol are computed and compared to experimental spectra measured in jet-cooled conditions in the region within 1000 cm-1 of the 0-0 transition. The agreement between theory and computation is satisfactory and allows a confident assignment of several experimental bands in terms of fundamentals of different modes. Cases are documented for which the analysis of optical anisotropy factors, owing to their signed nature, remarkably enhances the possibility of a robust assignment of the experimental absorption bands. Computational analysis shows that the experimental spectra are dominated by Herzberg-Teller contributions and that the electronic circular dichroism spectrum and the anisotropy factors are also strongly modulated by the effect of Duschinsky mixings.
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Affiliation(s)
- Fabrizio Santoro
- Istituto di Chimica dei Composti Organometallici, Consiglio Nazionale delle Ricerche, Area della Ricerca, via G. Moruzzi 1, I-56124, Pisa, Italy
| | - Farinaz Mortaheb
- Catalysis Research Center, Technische Universität München, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Jörn Lepelmeier
- Catalysis Research Center, Technische Universität München, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Ulrich Boesl
- Catalysis Research Center, Technische Universität München, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Ulrich Heiz
- Catalysis Research Center, Technische Universität München, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Aras Kartouzian
- Catalysis Research Center, Technische Universität München, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748, Garching, Germany
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18
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Lepelmeier J, Alonso-Gómez JL, Mortaheb F, Boesl U, Heiz U, Kartouzian A. Chiroptical inversion for isolated vibronic transitions of supersonic beam-cooled molecules. Phys Chem Chem Phys 2018. [PMID: 28650046 DOI: 10.1039/c7cp02596c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Circular dichroism-resonance-enhanced multiphoton ionization (CD-REMPI) was used for CD measurements on several single vibronic transitions of supersonic beam-cooled (R)-(+)-1-phenylethanol. Due to the low molecular densities within a supersonic beam and the expected small anisotropy factor of 1-phenylethanol in the permille region, the precision of the experimental method had to be significantly improved. Therefore, a single laser pulse evaluation combined with a twin-peak technique enabled within the used supersonic beam setup is presented. For the electronic transition S0 → S1 of (R)-(+)-1-phenylethanol (π → π* transition of the phenyl ring at 266 nm) ten different vibrational modes as well as the 0-transition were investigated with one-color (1 + 1) CD-REMPI. The results deliver new experimental insights on the influence of molecular vibrations on the anisotropy factor. TD-DFT theoretical predictions show how the angle between the electronic and magnetic transition dipole moments of the electronic transition can be modified by different vibrational modes, making even a flip of the sign of the anisotropy factor possible.
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Affiliation(s)
- Jörn Lepelmeier
- Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
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19
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Hong A, Moon CJ, Jang H, Min A, Choi MY, Heo J, Kim NJ. Isomer-Specific Induced Circular Dichroism Spectroscopy of Jet-Cooled Phenol Complexes with (-)-Methyl l-Lactate. J Phys Chem Lett 2018; 9:476-480. [PMID: 29309156 DOI: 10.1021/acs.jpclett.7b03241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Induced circular dichroism (ICD) is the CD observed in the absorption of an achiral molecule bound to a transparent chiral molecule through noncovalent interactions. ICD spectroscopy has been used to probe the binding between molecules, such as protein-ligand interactions. However, most ICD spectra have been measured in solution, which only exhibit the averaged CD values of all conformational isomers in solution. Here, we obtained the first isomer-selective ICD spectra by applying resonant two-photon ionization CD spectroscopy to jet-cooled phenol complexes with (-)-methyl l-lactate (PhOH-(-)ML). The well-resolved CD bands in the spectra were assigned to two conformers, which contained different types of hydrogen-bonding interactions between PhOH and (-)ML. The ICD values of the two conformers have different signs and magnitudes, which were explained by differences both in the geometrical asymmetries of PhOH bound to (-)ML and in the electronic coupling strengths between PhOH and (-)ML.
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Affiliation(s)
- Aram Hong
- Department of Chemistry, Chungbuk National University , Chungbuk 28644, Korea
| | - Cheol Joo Moon
- Department of Chemistry (BK21+) and Research Institute of Natural Science, Gyeongsang National University , Jinju 52828, Korea
| | - Heeseon Jang
- Department of Chemistry, Chungbuk National University , Chungbuk 28644, Korea
| | - Ahreum Min
- Department of Chemistry, Chungbuk National University , Chungbuk 28644, Korea
| | - Myong Yong Choi
- Department of Chemistry (BK21+) and Research Institute of Natural Science, Gyeongsang National University , Jinju 52828, Korea
| | - Jiyoung Heo
- Department of Green Chemical Engineering, Sangmyung University , Chungnam 31066, Korea
| | - Nam Joon Kim
- Department of Chemistry, Chungbuk National University , Chungbuk 28644, Korea
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Miles J, Fernandes D, Young A, Bond C, Crane S, Ghafur O, Townsend D, Sá J, Greenwood J. A new technique for probing chirality via photoelectron circular dichroism. Anal Chim Acta 2017; 984:134-139. [DOI: 10.1016/j.aca.2017.06.051] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/22/2017] [Accepted: 06/23/2017] [Indexed: 10/19/2022]
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21
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Kastner A, Ring T, Krüger BC, Park GB, Schäfer T, Senftleben A, Baumert T. Intermediate state dependence of the photoelectron circular dichroism of fenchone observed via femtosecond resonance-enhanced multi-photon ionization. J Chem Phys 2017; 147:013926. [DOI: 10.1063/1.4982614] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Yu X, Yao ZP. Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review. Anal Chim Acta 2017; 968:1-20. [DOI: 10.1016/j.aca.2017.03.021] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/15/2017] [Accepted: 03/16/2017] [Indexed: 10/19/2022]
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23
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Rebrov O, Kulyk K, Ryding M, Thomas RD, Uggerud E, Larsson M. Chirally sensitive collision induced dissociation of proton-bound diastereomeric complexes of tryptophan and 2-butanol. Chirality 2017; 29:115-119. [PMID: 28332282 DOI: 10.1002/chir.22679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 10/01/2017] [Accepted: 10/02/2017] [Indexed: 02/05/2023]
Abstract
In this work we report the stereo-dependent collision-induced dissociation (CID) of proton-bound complexes of tryptophan and 2-butanol. The dissociation efficiency was measured as a function of collision energy in single collision mode. The homochiral complex was found to be less stable against CID than a heterochiral one. Additional gas dependence measurements were performed with diastereomeric complexes that confirm the findings.
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Affiliation(s)
- Oleksii Rebrov
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - Kostiantyn Kulyk
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - Mauritz Ryding
- Department of Chemistry, University of Oslo, Oslo, Norway
| | - Richard D Thomas
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - Einar Uggerud
- Department of Chemistry, University of Oslo, Oslo, Norway
| | - Mats Larsson
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
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24
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Fu JY, Htar TT, De Silva L, Tan DMY, Chuah LH. Chromatographic Separation of Vitamin E Enantiomers. Molecules 2017; 22:E233. [PMID: 28165404 PMCID: PMC6155869 DOI: 10.3390/molecules22020233] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 01/27/2023] Open
Abstract
Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.
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Affiliation(s)
- Ju-Yen Fu
- Nutrition Unit, Product Development and Advisory Services Division, Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia.
| | - Thet-Thet Htar
- School of Pharmacy, Monash University Malaysia, Bandar Sunway, 47500 Subang Jaya, Selangor, Malaysia.
| | - Leanne De Silva
- School of Pharmacy, Monash University Malaysia, Bandar Sunway, 47500 Subang Jaya, Selangor, Malaysia.
| | - Doryn Meam-Yee Tan
- Nutrition Unit, Product Development and Advisory Services Division, Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia.
| | - Lay-Hong Chuah
- School of Pharmacy, Monash University Malaysia, Bandar Sunway, 47500 Subang Jaya, Selangor, Malaysia.
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Lepelmeier J, Titze K, Kartouzian A, Boesl U, Heiz U. Mass-Selected Circular Dichroism of Supersonic-Beam-Cooled [D 4 ]-(R)-(+)-3-Methylcyclopentanone. Chemphyschem 2016; 17:4052-4058. [PMID: 27809379 DOI: 10.1002/cphc.201600811] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/05/2016] [Indexed: 11/06/2022]
Abstract
UV spectroscopy and electronic circular dichroism (ECD) experiments on supersonic-beam-cooled deuterated (R)-(+)-3-methylcyclopentanone ([D4 ]-(R)-(+)-3-MCP) have been performed by using a laser mass spectrometer. The spectral resolution not only allowed excitation and CD measurements for single vibronic transitions but also for the rotational P, Q, and R branches of these transitions. The investigated n→π*18042501 transition showed the largest anisotropy factor ever observed for chiral molecules in the gas phase, which, due to residual saturation of the excited transition, represents only a lower limit for the real anisotropy factor. Furthermore, one-color (1+1+1) and two-color (1+1') resonance-enhanced multiphoton ionization (REMPI) measurements were performed and the effusive-beam (room temperature) and supersonic-beam results for [D4 ]-(R)-(+)-3-MCP were compared. These results allowed a differentiation between single-step ECD (comparable to conventional ECD) and cumulative ECD (only possible in multiphoton excitation) under supersonic-beam conditions.
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Affiliation(s)
- Jörn Lepelmeier
- Technische Universität München, Lehrstuhl für Physikalische Chemie, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Katharina Titze
- Technische Universität München, Lehrstuhl für Physikalische Chemie, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Aras Kartouzian
- Technische Universität München, Lehrstuhl für Physikalische Chemie, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Ulrich Boesl
- Technische Universität München, Lehrstuhl für Physikalische Chemie, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Ulrich Heiz
- Technische Universität München, Lehrstuhl für Physikalische Chemie, Lichtenbergstr. 4, 85748, Garching, Germany
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