1
|
Carlson CD, Ma J, Al-Jabiri MH, Insausti A, Xu Y. Conformational adaptation and large amplitude motions of 1-phenyl-2,2,2-trifluoroethanol with two water molecules: a rotational spectroscopic and ab initio investigation. Phys Chem Chem Phys 2024; 26:18067-18075. [PMID: 38895791 DOI: 10.1039/d4cp01516a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The 1 : 2 adduct of 1-phenyl-2,2,2-trifluoroethanol (PhTFE), a chiral fluoroalcohol, with two water molecules (PhTFE⋯2H2O) was investigated via chirped pulse Fourier-transform microwave (CP-FTMW) spectroscopy and theoretical calculations. A systematic search of the PhTFE⋯2H2O conformational landscape identified 38 stable minima at the B3LYP-D3BJ/def2-TZVPPD level of theory, 27 of which are within an energy window of 10 kJ mol-1 after applying zero-point energy corrections. Rotational spectra of a single PhTFE⋯2H2O conformer along with eight deuterated and three oxygen-18 isotopologues were assigned. Interestingly, the observed PhTFE⋯2H2O conformer contains PhTFE II, the second most stable monomer conformer, and the most stable PhTFE I dihydrate is ca. 4 kJ mol-1 higher in energy. In contrast, PhTFE I⋯H2O was identified experimentally and theoretically as the most stable 1 : 1 conformer. Furthermore, the observed dihydrate structure experiences large amplitude motions connecting three theoretical minima which differ only in which water oxygen lone pairs are involved in the hydrogen-bonds, i.e., the free OH pointing directions. Additionally, the ortho and para-H2O tunnelling splittings were detected and attributed to the interchange water hydrogen atoms which interact with the aromatic part of PhTFE but not for the water interacting with PhTFE hydroxy group. Extensive theoretical modelling was carried out to gain insight into the associated large amplitude motions including tunnelling, supported by the experimental isotopic and tunnelling splitting data.
Collapse
Affiliation(s)
- Colton D Carlson
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
| | - Jiarui Ma
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
| | - Mohamad H Al-Jabiri
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
| | - Aran Insausti
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
- Departamento de Quimica Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV-EHU), Bilbao 48080, Spain
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country (UPV/EHU), Leioa 48940, Spain
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
| |
Collapse
|
2
|
Lang J, Foley CD, Thawoos S, Behzadfar A, Liu Y, Zádor J, Suits AG. Reaction dynamics of S( 3P) with 1,3-butadiene and isoprene: crossed-beam scattering, low-temperature flow experiments, and high-level electronic structure calculations. Faraday Discuss 2024. [PMID: 38807494 DOI: 10.1039/d4fd00009a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Sulfur atoms serve as key players in diverse chemical processes, from astrochemistry at very low temperature to combustion at high temperature. Building upon our prior findings, showing cyclization to thiophenes following the reaction of ground-state sulfur atoms with dienes, we here extend this investigation to include many additional reaction products, guided by detailed theoretical predictions. The outcomes highlight the complex formation of products during intersystem crossing (ISC) to the singlet surfaces. Here, we employed crossed-beam velocity map imaging and high-level ab initio methods to explore the reaction of S(3P) with 1,3-butadiene and isoprene under single-collision conditions and in low-temperature flows. For the butadiene reaction, our experimental results show the formation of thiophene via H2 loss, a 2H-thiophenyl radical through H loss, and thioketene through ethene loss at a slightly higher collision energy compared to previous observations. Complementary Chirped-Pulse Fourier-Transform mmWave spectroscopy (CP-FTmmW) measurements in a uniform flow confirmed the formation of thioketene in the reaction at 20 K. For the isoprene reaction, we observed analogous products along with the 2H-thiophenyl radical arising from methyl loss and C3H4S (loss of ethene or H2 + acetylene). CP-FTmmW detected the formation of thioformaldehyde via loss of 1,3-butadiene, again in the 20 K flow. Coupled-cluster calculations on the pathways found by the automated kinetic workflow code KinBot support these findings and indicate ISC to the singlet surface, leading to the generation of various long-lived intermediates, including 5-membered heterocycles.
Collapse
Affiliation(s)
- Jinxin Lang
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Casey D Foley
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Shameemah Thawoos
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Abbas Behzadfar
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Yanan Liu
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Judit Zádor
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| |
Collapse
|
3
|
Crabtree KN, Westerfield JH, Dim CA, Meyer KS, Johansen SL, Buchanan ZS, Stucky PA. Rotational spectroscopy of methyl tert-butyl ether with a new Ka band chirped-pulse Fourier transform microwave spectrometer. Phys Chem Chem Phys 2024; 26:13694-13709. [PMID: 38666410 DOI: 10.1039/d4cp00797b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
Chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy is a powerful tool for performing broadband gas-phase rotational spectroscopy, and its applications include discovery of new molecules, complex mixture analysis, and exploration of fundamental molecular physics. Here we report the development of a new Ka band (26.5-40 GHz) CP-FTMW spectrometer that is equipped with a pulsed supersonic expansion source and a heated reservoir for low-volatility samples. The spectrometer is built around a 150 W traveling wave tube amplifier and has an instantaneous bandwidth that covers the entire Ka band spectral range. To test the performance of the spectrometer, the rotational spectrum of methyl tert-butyl ether (MTBE), a former gasoline additive and environmental pollutant, has been measured for the first time in this spectral range. Over 1000 spectroscopic transitions have been measured and assigned to the vibrational ground state and a newly-identified torsionally excited state; all transitions were fit using the XIAM program to a root-mean-square deviation of 22 kHz. The spectrum displays internal rotation splitting, nominally forbidden transitions, and an intriguing axis-switching effect between the ground and torsionally excited state that is a consequence of MTBE's extreme near-prolate nature. Finally, the sensitivity of the spectrometer enabled detection of all singly-substituted 13C and 18O isotopologues in natural abundance. This set of isotopic spectra allowed for a partial r0 structure involving the heavy atoms to be derived, resolving a structural discrepancy in the literature between previous microwave and electron diffraction measurements.
Collapse
Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - J H Westerfield
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Chisom A Dim
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Kelly S Meyer
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Sommer L Johansen
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Zachary S Buchanan
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Paul A Stucky
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| |
Collapse
|
4
|
Rowell CER, Kaur J, Zhang Y, Alzarieni KZ, Anyaeche RO, Ma HM, Little AM, Sharma T, Nussbaum MD, Hershberger DA, Lee YJ, Blagojevic V, Neill JL, Kenttämaa HI. Application of Laser-Induced Acoustic Desorption for Molecular Rotational Resonance Spectroscopy. Anal Chem 2024; 96:6255-6263. [PMID: 38588398 DOI: 10.1021/acs.analchem.3c05486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Molecular Rotational Resonance (MRR) spectroscopy is a uniquely precise tool for the determination of molecular structures of volatile compounds in mixtures, as the characteristic rotational transition frequencies of a molecule are extremely sensitive to its 3D structure through the moments of inertia in a three-dimensional coordinate system. This enables identification of the compounds based on just a few parameters that can be calculated, as opposed to, for example, mass spectrometric data, which often require expert analysis of 10-20 different signals and the use of many standards/model compounds. This paper introduces a new sampling technique for MRR, laser-induced acoustic desorption (LIAD), to allow the vaporization of nonvolatile and thermally labile analytes without the need for excessive heating or derivatization. In this proof-of-concept study, LIAD was successfully coupled to an MRR instrument to conduct measurements on seven compounds with differing polarities, molecular weights, and melting and boiling points. Identification of three isomers in a mixture was also successfully performed using LIAD/MRR. Based on these results, LIAD/MRR is demonstrated to provide a powerful approach for the identification of nonvolatile and/or thermally labile analytes with molecular weights up to 600 Da in simple mixtures, which does not require the use of reference compounds. In the future, applications to more complex mixtures, such as those relevant to pharmaceutical research, and quantitative aspects of LIAD/MRR will be reported.
Collapse
Affiliation(s)
- Caroline E R Rowell
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Jaskiran Kaur
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Yuyang Zhang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Kawthar Z Alzarieni
- Jordan University of Science and Technology, Faculty of Pharmacy, Department of Medicinal Chemistry and Pharmacognosy, Irbid 22110, Jordan
| | - Ruth O Anyaeche
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Hendrik M Ma
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Annika M Little
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Tanya Sharma
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Matthan D Nussbaum
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Drake A Hershberger
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Ying-Jou Lee
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | | | - Justin L Neill
- BrightSpec Inc., Charlottesville, Virginia 22903, United States
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| |
Collapse
|
5
|
Lu T, Xie F, Seifert NA, Hamidi Mejlej R, Jäger W, Xu Y. Binary conformers of a flexible, long-chain fluoroalcohol: dispersion controlled selectivity and relative abundances in a jet. Phys Chem Chem Phys 2024; 26:10538-10545. [PMID: 38505957 DOI: 10.1039/d4cp00401a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
The complex conformational panorama of binary 4,4,4-trifluoro-1-butanol (TFB) aggregates was investigated using chirped-pulse Fourier transform microwave spectroscopy, aided by conformational searches using CREST (Conformer-Rotamer Ensemble Sampling Tool) and quantum chemistry calculations. From nearly 1500 initial dimer geometries, 16 most stable binary candidates were obtained within a relative energy window of ∼4 kJ mol-1. Rotational spectra of five binary conformers were experimentally observed in supersonic expansion and assigned. Interestingly, three out of the five observed binary conformers are composed solely of monomer conformers, which were not observed in their isolated gas phase forms in jet expansion. In addition, an observed dimer that is made exclusively of the most stable TFB monomer subunits does not correspond to the global minimum. The intricate kinetically and thermodynamically controlled dimer formation mechanisms are discussed, and a modified kinetic-thermodynamic model was developed, providing conformational abundances that are in good agreement with the experiment. Subsequent non-covalent interaction analyses reveal that the observed conformers are held together by one primary O-H⋯O hydrogen bond and secondary intermolecular C-H⋯O, C-H⋯F, and/or O-H⋯F interactions, as well as C-H⋯H-C London dispersion interactions between the methylene groups. Further symmetry-adapted perturbation theory analyses of the TFB dimer conformers and related alcohol dimers reveal a considerable rise in dispersion contributions with increasing n-alkyl carbon chain length and highlight the role of dispersion interactions in preferentially stabilizing the global minimum of the TFB dimer.
Collapse
Affiliation(s)
- Tao Lu
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
- Key Laboratory of Biology and Medical Engineering, School of Biology and Engineering, Guizhou Medical University, Guiyang 550025, China
| | - Fan Xie
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
| | - Nathan A Seifert
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
- Chemistry and Chemical & Biomedical Engineering Department, University of New Haven, 300 Boston Post Rd, West Haven, CT 06516, USA
| | - Reihaneh Hamidi Mejlej
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
| | - Wolfgang Jäger
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada.
| |
Collapse
|
6
|
Thawoos S, Suas-David N, Gurusinghe RM, Edlin M, Behzadfar A, Lang J, Suits AG. Low temperature reaction kinetics inside an extended Laval nozzle: REMPI characterization and detection by broadband rotational spectroscopy. J Chem Phys 2023; 159:214201. [PMID: 38054511 DOI: 10.1063/5.0178533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
Chirped-Pulse Fourier-Transform millimeter wave (CP-FTmmW) spectroscopy is a powerful method that enables detection of quantum state specific reactants and products in mixtures. We have successfully coupled this technique with a pulsed uniform Laval flow system to study photodissociation and reactions at low temperature, which we refer to as CPUF ("Chirped-Pulse/Uniform flow"). Detection by CPUF requires monitoring the free induction decay (FID) of the rotational coherence. However, the high collision frequency in high-density uniform supersonic flows can interfere with the FID and attenuate the signal. One way to overcome this is to sample the flow, but this can cause interference from shocks in the sampling region. This led us to develop an extended Laval nozzle that creates a uniform flow within the nozzle itself, after which the gas undergoes a shock-free secondary expansion to cold, low pressure conditions ideal for CP-FTmmW detection. Impact pressure measurements, commonly used to characterize Laval flows, cannot be used to monitor the flow within the nozzle. Therefore, we implemented a REMPI (resonance-enhanced multiphoton ionization) detection scheme that allows the interrogation of the conditions of the flow directly inside the extended nozzle, confirming the fluid dynamics simulations of the flow environment. We describe the development of the new 20 K extended flow, along with its characterization using REMPI and computational fluid dynamics. Finally, we demonstrate its application to the first low temperature measurement of the reaction kinetics of HCO with O2 and obtain a rate coefficient at 20 K of 6.66 ± 0.47 × 10-11 cm3 molec-1 s-1.
Collapse
Affiliation(s)
- Shameemah Thawoos
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Nicolas Suas-David
- Univ Rennes, CNRS, Institut de Physique de Rennes - UMR 6251, F-35000 Rennes, France
| | - Ranil M Gurusinghe
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
- Department of Chemistry, Tennessee Tech University, Cookeville, Tennessee 38505, USA
| | - Matthew Edlin
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Abbas Behzadfar
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Jinxin Lang
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| |
Collapse
|
7
|
Xie F, Sun W, Hartwig B, Obenchain DA, Schnell M. Hydrogen-Atom Tunneling in a Homochiral Environment. Angew Chem Int Ed Engl 2023; 62:e202308273. [PMID: 37467465 DOI: 10.1002/anie.202308273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
The role-exchanging concerted torsional motion of two hydrogen atoms in the homochiral dimer of trans-1,2-cyclohexanediol was characterized through a combination of broadband rotational spectroscopy and theoretical modeling. The results reveal that the concerted tunneling motion of the hydrogen atoms leads to the inversion of the sign of the dipole moment components along the a and b principal axes, due to the interchange motion that cooperatively breaks and reforms one intermolecular hydrogen bond. This motion is also coupled with two acceptor switching motions. The energy difference between the two ground vibrational states arising from this tunneling motion was determined to be 29.003(2) MHz. The corresponding wavefunctions suggest that the two hydrogen atoms are evenly delocalized on two equivalent potential wells, which differs from the heterochiral case where the hydrogen atoms are confined in separate wells, as the permutation-inversion symmetry breaks down. This intriguing contrast in hydrogen-atom behavior between homochiral and heterochiral environments could further illuminate our understanding of the role of chirality in intermolecular interactions and dynamics.
Collapse
Affiliation(s)
- Fan Xie
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Wenhao Sun
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Beppo Hartwig
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, 37077, Göttingen, Germany
| | - Daniel A Obenchain
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, 37077, Göttingen, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| |
Collapse
|
8
|
Borengasser Q, Hager T, Kanaherarachchi A, Troya D, Broderick BM. Conformer-Specific Desorption in Propanol Ices Probed by Chirped-Pulse Millimeter-Wave Rotational Spectroscopy. J Phys Chem Lett 2023:6550-6555. [PMID: 37450900 DOI: 10.1021/acs.jpclett.3c01468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
We present a new technique for the detection of molecules desorbed from an ice surface using broad-band millimeter-wave rotational spectroscopy. The approach permits interrogation of molecules that have undergone the slow warmup process of temperature-programmed desorption (TPD), analogous to the warmup phase of icy grains in the interstellar medium as they approach the central protostar. The detection is conformer- and isomer-specific and quantitative, as afforded by chirped-pulse rotational spectroscopy. To achieve this, we combine ice TPD with buffer gas cooling, followed by detection in the millimeter-wave regime. In this report we examine the TPD profiles of n- and i-propanol, the former of which may be in five different conformational isomeric forms, and which display distinct desorption profiles. The limited conformational isomerization and temperature-dependent relative yields of n-propanol conformers observed show that the desorption is highly conformer-specific.
Collapse
Affiliation(s)
- Quentin Borengasser
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Travis Hager
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Anudha Kanaherarachchi
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Diego Troya
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Bernadette M Broderick
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| |
Collapse
|
9
|
Mishra P, Hull AW, Coy SL, Field RW. Signatures of Reaction Mechanisms Encoded in the Vibrational Population Distribution of Small-Molecule Products: Photodissociation of Symmetric-Triazine Using 266 nm Radiation. J Phys Chem Lett 2023; 14:3706-3711. [PMID: 37040597 DOI: 10.1021/acs.jpclett.3c00597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
We utilize rotationally resolved Chirped-Pulse Fourier Transform millimeter-wave spectroscopy to study photodissociation dynamics of 1,3,5-Triazine (symmetric-Triazine) to form 3 HCN molecules. The state-specific vibrational population distribution (VPD) of the photofragments contains mechanistic details of the reaction. This photodissociation is performed using 266 nm radiation transverse to a seeded supersonic jet. The vibrational cooling inefficiency in the jet preserves the VPD of the photofragments, while rotational cooling enhances the signal of low-J pure-rotational transitions. The multiplexed nature of the spectrometer enables simultaneous sampling of several "vibrational satellites" of the J = 1 ← 0 transition of HCN. Excited state populations along the HCN bend (v2) and CN stretch (v3) modes are observed, which show ≥3.2% vibrational excitation of the photofragments. Observation of an at least bimodal VPD, along the even-v states of v2, implies an asymmetric partitioning of vibrational energy among the HCN photofragments. This suggests a sequential dissociation mechanism of symmetric-Triazine initiated by 266 nm radiation.
Collapse
Affiliation(s)
- Piyush Mishra
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexander W Hull
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen L Coy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
10
|
Xie F, Sun W, Pinacho P, Schnell M. CO 2 Aggregation on Monoethanolamine: Observations from Rotational Spectroscopy. Angew Chem Int Ed Engl 2023; 62:e202218539. [PMID: 36719030 DOI: 10.1002/anie.202218539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/01/2023]
Abstract
The initial stages of the gas-phase nucleation between CO2 and monoethanolamine were investigated via broadband rotational spectroscopy with the aid of extensive theoretical structure sampling. Sub-nanometer-scale aggregation patterns of monoethanolamine-(CO2 )n , n=1-4, were identified. An interesting competition between the monoethanolamine intramolecular hydrogen bond and the intermolecular interactions between monoethanolamine and CO2 upon cluster growth was discovered, revealing an intriguing CO2 binding priority to the hydroxyl group over the amine group. These findings are in sharp contrast to the general results for aqueous solutions. In the quinary complex, a cap-like CO2 tetramer was observed cooperatively surrounding the monoethanolamine. As the cluster approaches the critical size of new particle formation, the contribution of CO2 self-assembly to the overall stability increases.
Collapse
Affiliation(s)
- Fan Xie
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Wenhao Sun
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Pablo Pinacho
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.,Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| |
Collapse
|
11
|
Hermanns M, Wehres N, Heyne B, Honingh CE, Graf UU, Schlemmer S. Performance of a chirped-pulse Fourier transform millimeter wave spectrometer in the range of 75-110 GHz. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:034705. [PMID: 37012769 DOI: 10.1063/5.0141579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/21/2023] [Indexed: 06/19/2023]
Abstract
We present a home-built chirped-pulse Fourier transform millimeter wave (CP-FTMMW) spectrometer. The setup is devoted to the sensitive recording of high-resolution molecular spectroscopy in the W band between 75 and 110 GHz. We describe the experimental setup in detail, including a characterization of the chirp excitation source, the optical beam path, and the receiver. The receiver is a further development of our 100 GHz emission spectrometer. The spectrometer is equipped with a pulsed jet expansion and a DC discharge. Spectra of methyl cyanide as well as hydrogen cyanide (HCN) and hydrogen isocyanide (HNC) products from the DC discharge of this molecule are recorded to characterize the performance of the CP-FTMMW instrument. The formation of the HCN isomer is favored by a factor of 63 with respect to HNC. Hot/cold calibration measurements enable a direct comparison of the signal and noise levels of the CP-FTMMW spectra to those of the emission spectrometer. For the CP-FTMMW instrument, we find many orders of magnitude of signal enhancement and a much stronger noise reduction due to the coherent detection scheme.
Collapse
Affiliation(s)
- M Hermanns
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - N Wehres
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - B Heyne
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - C E Honingh
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - U U Graf
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| | - S Schlemmer
- I. Physikalisches Institut, Zülpicher Str. 77, 50937 Köln, Germany
| |
Collapse
|
12
|
Baweja S, Antonelli E, Hussain S, Fernández-Ramos A, Kleiner I, Nguyen HVL, Sanz ME. Revealing Internal Rotation and 14N Nuclear Quadrupole Coupling in the Atmospheric Pollutant 4-Methyl-2-nitrophenol: Interplay of Microwave Spectroscopy and Quantum Chemical Calculations. Molecules 2023; 28:molecules28052153. [PMID: 36903397 PMCID: PMC10004196 DOI: 10.3390/molecules28052153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/17/2023] [Accepted: 02/17/2023] [Indexed: 03/02/2023] Open
Abstract
The structure and interactions of oxygenated aromatic molecules are of atmospheric interest due to their toxicity and as precursors of aerosols. Here, we present the analysis of 4-methyl-2-nitrophenol (4MNP) using chirped pulse and Fabry-Pérot Fourier transform microwave spectroscopy in combination with quantum chemical calculations. The rotational, centrifugal distortion, and 14N nuclear quadrupole coupling constants of the lowest-energy conformer of 4MNP were determined as well as the barrier to methyl internal rotation. The latter has a value of 106.4456(8) cm-1, significantly larger than those from related molecules with only one hydroxyl or nitro substituent in the same para or meta positions, respectively, as 4MNP. Our results serve as a basis to understand the interactions of 4MNP with atmospheric molecules and the influence of the electronic environment on methyl internal rotation barrier heights.
Collapse
Affiliation(s)
- Shefali Baweja
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Eleonore Antonelli
- Université Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
| | - Safia Hussain
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Antonio Fernández-Ramos
- Departamento de Química Física and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Jenaro de la Fuente s/n, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Isabelle Kleiner
- Université Paris Cité and Université Paris Est Créteil, CNRS, LISA, F-75013 Paris, France
| | - Ha Vinh Lam Nguyen
- Université Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
- Institut Universitaire de France (IUF), 1 rue Descartes, F-75231 Paris, France
- Correspondence: (H.V.L.N.); (M.E.S.)
| | - M. Eugenia Sanz
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
- Correspondence: (H.V.L.N.); (M.E.S.)
| |
Collapse
|
13
|
Li W, Pérez C, Steber AL, Schnell M, Lv D, Wang G, Zeng X, Zhou M. Evolution of Solute-Water Interactions in the Benzaldehyde-(H 2O) 1-6 Clusters by Rotational Spectroscopy. J Am Chem Soc 2023; 145:4119-4128. [PMID: 36762446 DOI: 10.1021/jacs.2c11732] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The investigation on the preferred arrangement and intermolecular interactions of gas phase solute-water clusters gives insights into the intermolecular potentials that govern the structure and dynamics of the aqueous solutions. Here, we report the investigation of hydrated coordination networks of benzaldehyde-(water)n (n = 1-6) clusters in a pulsed supersonic expansion using broadband rotational spectroscopy. Benzaldehyde (PhCHO) is the simplest aromatic aldehyde that involves both hydrophilic (CHO) and hydrophobic (phenyl ring) functional groups, which can mimic molecules of biological significance. For the n = 1-3 clusters, the water molecules are connected around the hydrophilic CHO moiety of benzaldehyde through a strong CO···HO hydrogen bond and weak CH···OH hydrogen bond(s). For the larger clusters, the spectra are consistent with the structures in which the water clusters are coordinated on the surface of PhCHO with both the hydrophilic CHO and hydrophobic phenyl ring groups being involved in the bonding interactions. The presence of benzaldehyde does not strongly interfere with the cyclic water tetramer and pentamer, which retain the same structure as in the pure water cluster. The book isomer instead of cage or prism isomers of the water hexamer is incorporated into the microsolvated cluster. The PhCHO molecule deviates from the planar structure upon sequential addition of water molecules. The PhCHO-(H2O)1-6 clusters may serve as a simple model system in understanding the solute-water interactions of biologically relevant molecules in an aqueous environment.
Collapse
Affiliation(s)
- Weixing Li
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China
| | - Cristóbal Pérez
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Amanda L Steber
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Christian-Albrechts-Universität zu Kiel, Institute of Physical Chemistry, Max-Eyth-Str. 1, 24118 Kiel, Germany
| | - Dingding Lv
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China
| | - Guanjun Wang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China
| | - Xiaoqing Zeng
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China
| | - Mingfei Zhou
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China
| |
Collapse
|
14
|
Dohmen R, Fedosov D, Obenchain DA. Benchmarking the quadrupolar coupling tensor for chlorine to probe weak-bonding interactions. Phys Chem Chem Phys 2023; 25:2420-2429. [PMID: 36598167 DOI: 10.1039/d2cp04067k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rotational spectroscopy relies on quantum chemical calculations to interpret observed spectra. Among the most challenging molecules to assign are those with additional angular momenta coupling to the rotation, contributing to the complexity of the spectrum. This benchmark study of computational methods commonly used by rotational spectroscopists targets the nuclear quadrupole coupling constants of chlorine containing molecules and the geometry of its complexes and clusters. For each method, the quality of both structural and electronic parameter predictions is compared with the experimental values. Ab initio methods are found to perform best overall in predicting both the geometry of the complexes and the coupling constants of chlorine with moderate computational cost. This cost can be reduced by combining these methods with density functional theory structure optimization, which still yields adequate predictions. This work constitutes a first step in expanding Bailey's quadrupole coupling data set to encompass molecular clusters. [W. C. Bailey, Calculation of Nuclear Quadrupole Coupling Constants in Gaseous State Molecule, 2019, https://nqcc.wcbailey.net/].
Collapse
Affiliation(s)
- Robin Dohmen
- Georg-August University, Tammannstraße 6, Göttingen, Germany.
| | - Denis Fedosov
- Georg-August University, Tammannstraße 6, Göttingen, Germany.
| | | |
Collapse
|
15
|
Saragi R, Calabrese C, Juanes M, Pinacho R, Rubio JE, Pérez C, Lesarri A. π-Stacking Isomerism in Polycyclic Aromatic Hydrocarbons: The 2-Naphthalenethiol Dimer. J Phys Chem Lett 2023; 14:207-213. [PMID: 36583611 PMCID: PMC9841560 DOI: 10.1021/acs.jpclett.2c03299] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
π-Stacking is a common descriptor for face-to-face attractive forces between aromatic hydrocarbons. However, the physical origin of this interaction remains debatable. Here we examined π-stacking in a model homodimer formed by two thiol-substituted naphthalene rings. Two isomers of the 2-naphthalenethiol dimer were discovered using rotational spectroscopy, sharing a parallel-displaced crossed orientation and absence of thiol-thiol hydrogen bonds. One of the isomers presents C2 symmetry, structurally analogous to the global minimum of the naphthalene dimer. The experimental data were rationalized with molecular orbital calculations, revealing a shallow potential energy surface. Noncovalent interactions are dominated by dispersion forces according to SAPT energy decomposition. In addition, the reduced electronic density shows a diffuse and extended region of inter-ring interactions, compatible with the description of π-stacking as a competition between dispersion and Pauli repulsion forces.
Collapse
Affiliation(s)
- Rizalina
Tama Saragi
- Departamento
de Química Física y Química Inorgánica,
Facultad de Ciencias - I.U. CINQUIMA, Universidad
de Valladolid, Paseo de Belén, 7, E-47011 Valladolid, Spain
| | - Camilla Calabrese
- Departamento
de Química Física y Química Inorgánica,
Facultad de Ciencias - I.U. CINQUIMA, Universidad
de Valladolid, Paseo de Belén, 7, E-47011 Valladolid, Spain
| | - Marcos Juanes
- Departamento
de Química Física y Química Inorgánica,
Facultad de Ciencias - I.U. CINQUIMA, Universidad
de Valladolid, Paseo de Belén, 7, E-47011 Valladolid, Spain
| | - Ruth Pinacho
- Departamento
de Electrónica, ETSIT, Universidad
de Valladolid, Paseo de Belén, 11, E-47011 Valladolid, Spain
| | - José Emiliano Rubio
- Departamento
de Electrónica, ETSIT, Universidad
de Valladolid, Paseo de Belén, 11, E-47011 Valladolid, Spain
| | - Cristóbal Pérez
- Departamento
de Química Física y Química Inorgánica,
Facultad de Ciencias - I.U. CINQUIMA, Universidad
de Valladolid, Paseo de Belén, 7, E-47011 Valladolid, Spain
| | - Alberto Lesarri
- Departamento
de Química Física y Química Inorgánica,
Facultad de Ciencias - I.U. CINQUIMA, Universidad
de Valladolid, Paseo de Belén, 7, E-47011 Valladolid, Spain
| |
Collapse
|
16
|
Wahab MF, Neill JL, Armstrong DW. Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography-Molecular Rotational Resonance Spectroscopy without Fourier Transforms. Anal Chem 2022; 94:14611-14617. [PMID: 36219766 DOI: 10.1021/acs.analchem.2c02535] [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
The concept of coupling gas chromatography with molecular rotational resonance spectroscopy (GC-MRR) was introduced in 2020, combining the separation capabilities of GC with the unparalleled specificity of MRR. In this study, we address the challenge of the high data throughput of MRR spectrometers, as GC-MRR spectrometers can generate thousands to millions of data points per second. In the previous GC-MRR studies, a free induction decay (FID) measurement was Fourier transformed to generate each point on the chromatogram. Such extensive calculations limit the performance, sensitivity, and speed of GC-MRR. A direct approach is proposed here to extract peak intensity from FID using the Gram-Schmidt vector orthogonalization method. First, analyte-free FIDs are used to construct a basis set representing the instrument's background noise, and then the remaining FIDs are orthogonalized to this fixed basis set. Each FID yields a single intensity value after Gram-Schmidt orthogonalization. The magnitude of the orthogonalized analyte FID is the signal intensity plotted in the chromatogram. This approach is computationally much faster (up to 10 times) than the conventional Fourier transform algorithm, is at least as sensitive as the FT algorithm, and maintains or improves the chromatographic peak shape. We compare the sensitivity, linearity, and chromatographic peak shapes for the Fourier transform and Gram-Schmidt approaches using both synthetically generated FIDs and instrumental data. This approach would allow the summed peak intensity to be displayed essentially in real-time, following which identified peaks can be further investigated to identify and quantify the species associated with each.
Collapse
Affiliation(s)
- M Farooq Wahab
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Arlington, Texas76019, United States
| | - Justin L Neill
- BrightSpec, Inc., 770 Harris St., Suite 104b, Charlottesville, Virginia22903, United States
| | - Daniel W Armstrong
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Arlington, Texas76019, United States
| |
Collapse
|
17
|
Carlson CD, Hazrah AS, Mason D, Yang Q, Seifert NA, Xu Y. Alternating 1-Phenyl-2,2,2-Trifluoroethanol Conformational Landscape With the Addition of One Water: Conformations and Large Amplitude Motions. J Phys Chem A 2022; 126:7250-7260. [PMID: 36191084 DOI: 10.1021/acs.jpca.2c05803] [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
The 1:1 adduct of 1-phenyl-2,2,2-trifluoroethanol (PhTFE), a chiral fluoroalcohol, with water was investigated using chirped pulse Fourier transform microwave spectroscopy and computational methods. While PhTFE itself was predicted to have three minima, I (gauche+), II (trans), and III (gauche-), only I and II were stable and only I was observed experimentally. A systematic search of the PhTFE···H2O conformational landscape identified 110 stable minima, 14 of which are within a 15 kJ mol-1 energy window. Rotational spectra of the two PhTFE···H2O conformers along with several deuterium and 18O isotopologues were assigned, and the isotopic data were used to verify the corresponding structures. In the two observed monohydrate conformers, one contains PhTFE I where the water subunit is inserted into the existing intramolecular OH···F contact of I, and the binary adduct is stabilized by two intermolecular contacts: OH···OW and HW···F, whereas the other contains PhTFE II where the water subunit interacts with both the alcohol hydrogen and phenyl ring of II, demonstrating that interaction with water sufficiently stabilizes II for its observation in a jet expansion. Interestingly, the predicted electric dipole moment components at the identified minima deviate considerably from the experimental ones. Such deviations were analyzed in terms of dynamic effects associated with the large amplitude motions of the unbound HW. In addition, tunnelling effects associated with the exchange of the bonded and nonbonded HW were also discussed.
Collapse
Affiliation(s)
- Colton D Carlson
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Arsh S Hazrah
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Daniel Mason
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Qian Yang
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Nathan A Seifert
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.,Department of Chemistry and Chemical & Biomedical Engineering, University of New Haven, 300 Boston Post Rd, West Haven, Connecticut 06516, United States
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| |
Collapse
|
18
|
A Scent of Peppermint—A Microwave Spectroscopy Analysis on the Composition of Peppermint Oil. Symmetry (Basel) 2022. [DOI: 10.3390/sym14061262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Essential oils have a vast number of applications in different areas of our daily life. Detailed chiral analysis and structural characterization of their constituents remains an important subject in analytical chemistry. Here, we report on a broadband rotational spectroscopy study of peppermint oil in the frequency range 2–8 GHz. We focus on an unambiguous determination of the excess enantiomers of the oil constituents menthone and isomenthone in the oil by applying chirality-sensitive rotational spectroscopy, the so-called microwave three-wave mixing (M3WM) technique. Additionally, a new menthol conformer, not previously characterized, was experimentally observed, and the gas-phase structures of the two conformers of menthol and menthone were determined experimentally based on the assignment of their 13C-isotopologues in natural abundance.
Collapse
|
19
|
Yang Q, Carlson CD, Jäger W, Xu Y. Conformational Landscape of the Hydrogen-Bonded 1-Phenyl-2,2,2-Trilfuoroethanol···1,4-Dioxane Complex: Dispersion Interactions and Conformational Conversion. J Phys Chem A 2022; 126:2942-2949. [PMID: 35507825 DOI: 10.1021/acs.jpca.2c01667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A rotational spectrum of the hydrogen-bonded complex between 1-phenyl-2,2,2-trilfuoroethanol (PhTFE), a chiral fluoroalcohol, and 1,4-dioxane, a common solvent for organic reactions, was measured using a chirped pulse Fourier transform microwave spectrometer. Initial theoretical conformational searches were carried out using CREST, a recently developed conformational searching tool. Subsequent geometry optimization and harmonic frequency calculations at the B3LYP-D3(BJ)/def2-TZVP level of theory yielded nearly 30 binary conformers of which 13 are within an energy window of ∼5 kJ mol-1. Interestingly, while the O-H···O hydrogen bond dominates the attractive binary interactions, the complex conformational landscape is mainly controlled by subtle dispersion interactions between the phenyl and 1,4-dioxane rings. Two sets of rotational transitions were assigned in the experimental spectrum and attributed to the two most stable conformers of PhTFE···1,4-dioxane. The quantum theory of atoms in molecules (QTAIM), noncovalent interactions (NCI), and symmetry-adapted perturbation theory (SAPT) analyses were employed in order to appreciate how the phenyl ring and O-H functional groups influence the intermolecular interaction and conformational distribution of the binary complex. The main PhTFE conformation within the complex, identified experimentally, is different from that of the isolated PhTFE monomer reported previously.
Collapse
Affiliation(s)
- Qian Yang
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Colton D Carlson
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Wolfgang Jäger
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| |
Collapse
|
20
|
Abstract
Two molecules are enantiomers if they are nonsuperimposable mirror images of each other. Electric dipole-allowed cyclic transitions |1⟩ → |2⟩ → |3⟩ → |1⟩ obey the symmetry relation OR=-OS, where OR,S = (μ21R,SE21)(μ13R,SE13)(μ32R,SE32) and R and S label the two enantiomers. Herein, we generalize the concept of topological frequency conversion to an ensemble of enantiomers. We show that, within a rotating-frame, the pumping power between fields of frequency ω1 and ω2 is sensitive to enantiomeric excess, P2→1 = ℏ[ω1ω2CLR/(2π)](NR - NS), where Ni is the number of enantiomers i and CLR is an enantiomer-dependent Chern number. Connections with chiroptical microwave spectroscopy are made. Our work provides an underexplored and fertile connection between topological physics and molecular chirality.
Collapse
Affiliation(s)
- Kai Schwennicke
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| |
Collapse
|
21
|
Stroud JR, Plusquellic DF. Difference-frequency chirped-pulse dual-comb generation in the THz region: Temporal magnification of the quantum dynamics of water vapor lines by >60 000. J Chem Phys 2022; 156:044302. [DOI: 10.1063/5.0076506] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Jasper R. Stroud
- Applied Physics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - David F. Plusquellic
- Applied Physics Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| |
Collapse
|
22
|
Singh H, Pinacho P, Obenchain DA, Quesada-Moreno MM, Schnell M. The many forms of alpha-methoxy phenylacetic acid in the gas phase: flexibility, internal dynamics, and their intramolecular interactions. Phys Chem Chem Phys 2022; 24:27312-27320. [DOI: 10.1039/d2cp03962a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Five conformers of the flexible molecule alpha-methoxy phenylacetic acid were identified using rotational spectroscopy. The conformational landscape, internal dynamics, and intramolecular interactions were investigated.
Collapse
Affiliation(s)
- Himanshi Singh
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
- Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118 Kiel, Germany
| | - Pablo Pinacho
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Daniel A. Obenchain
- Institut fur Physikalische Chemie, Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - María Mar Quesada-Moreno
- Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada, Spain
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
- Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118 Kiel, Germany
| |
Collapse
|
23
|
Barber VP, Kroll JH. Chemistry of Functionalized Reactive Organic Intermediates in the Earth's Atmosphere: Impact, Challenges, and Progress. J Phys Chem A 2021; 125:10264-10279. [PMID: 34846877 DOI: 10.1021/acs.jpca.1c08221] [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
The gas-phase oxidation of organic compounds is an important chemical process in the Earth's atmosphere. It governs oxidant levels and controls the production of key secondary pollutants, and hence has major implications for air quality and climate. Organic oxidation is largely controlled by the chemistry of a few reactive intermediates, namely, alkyl (R) radicals, alkoxy (RO) radicals, peroxy (RO2) radicals, and carbonyl oxides (R1R2COO), which may undergo a number of unimolecular and bimolecular reactions. Our understanding of these intermediates, and the reaction pathways available to them, is based largely on studies of unfunctionalized intermediates, formed in the first steps of hydrocarbon oxidation. However, it has become increasingly clear that intermediates with functional groups, which are generally formed later in the oxidation process, can exhibit fundamentally different reactivity than unfunctionalized ones. In this Perspective, we explore the unique chemistry available to functionalized organic intermediates in the Earth's atmosphere. After a brief review of the canonical chemistry available to unfunctionalized intermediates, we discuss how the addition of functional groups can introduce new reactions, either by changing the energetics or kinetics of a given reaction or by opening up new chemical pathways. We then provide examples of atmospheric reaction classes that are available only to functionalized intermediates. Some of these, such as unimolecular H-shift reactions of RO2 radicals, have been elucidated only relatively recently, and can have important impacts on atmospheric chemistry (e.g., on radical cycling or organic aerosol formation); it seems likely that other, as-yet undiscovered reactions of (multi)functional intermediates may also exist. We discuss the challenges associated with the study of the chemistry of such intermediates and review novel experimental and theoretical approaches that have recently provided (or hold promise for providing) new insights into their atmospheric chemistry. The continued use and development of such techniques and the close collaboration between experimentalists and theoreticians are necessary for a complete, detailed understanding of the chemistry of functionalized intermediates and their impact on major atmospheric chemical processes.
Collapse
Affiliation(s)
- Victoria P Barber
- Departments of Civil and Environmental Engineering and Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jesse H Kroll
- Departments of Civil and Environmental Engineering and Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
24
|
Garrett T, Elle J, White M, Reid R, Englesbe A, Phillips R, Mardahl P, Thornton E, Wymer J, Janicek A, Sale O, Schmitt-Sody A. Generation of radio frequency radiation by femtosecond filaments. Phys Rev E 2021; 104:L063201. [PMID: 35030950 DOI: 10.1103/physreve.104.l063201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
Recent experiments have shown that femtosecond filamentation plasmas generate ultrabroadband radio frequency radiation (RF). We show that a combination of plasma dynamics is responsible for the RF: A plasma wake field develops behind the laser pulse, and this wake excites (and copropagates with) a surface wave on the plasma column. The surface wave proceeds to detach from the end of the plasma and propagates forward as the RF pulse. We have developed a four-stage model of these plasma wake surface waves and find that it accurately predicts the RF from a wide range of experiments, including both 800-nm and 3.9-μm laser systems.
Collapse
Affiliation(s)
- Travis Garrett
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Jennifer Elle
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Michael White
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Remington Reid
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Alexander Englesbe
- Naval Research Laboratory, Plasma Physics Division, Washington, DC 20375, USA
| | - Ryan Phillips
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Peter Mardahl
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Erin Thornton
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - James Wymer
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| | - Anna Janicek
- Leidos Innovations Center, Albuquerque, New Mexico 87106, USA
| | - Oliver Sale
- Leidos Innovations Center, Albuquerque, New Mexico 87106, USA
| | - Andreas Schmitt-Sody
- Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 87123, USA
| |
Collapse
|
25
|
Wahab MF, Aslani S, Mikhonin AV, Neill JL, Armstrong DW. Enhancing Sensitivity for High-Selectivity Gas Chromatography-Molecular Rotational Resonance Spectroscopy. Anal Chem 2021; 93:15525-15533. [PMID: 34748700 DOI: 10.1021/acs.analchem.1c03710] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A next-generation gas chromatograph-molecular rotational resonance (MRR) spectrometer (GC-MRR) with instrumental improvements and higher sensitivity is described. MRR serves as a structural information-rich detector for GC with extremely narrow linewidths and capabilities surpassing 1H nuclear magnetic resonance/Fourier transform infrared spectroscopy/mass spectrometry (MS) while offering unparalleled specificity in regard to a molecule's three-dimensional structure. With a Fabry-Pérot cavity and a supersonic jet incorporated into a GC-MRR, dramatic improvements in sensitivity for molecules up to 244 Da were achieved in the microwave region compared to the only prior work, which demonstrated the GC-MRR idea for the first time with millimeter waves. The supersonic jet cools the analytes to ∼2 K, resulting in a limited number of molecular rotational and vibrational levels and enabling us to obtain stronger GC-MRR signals. This has allowed the limits of detection of the GC-MRR to be comparable to a GC thermal conductivity detector with an optimized choice of gases. The performance of this GC-MRR system is reported for a range of molecules with permanent dipole moments, including alcohols, nitrogen heterocyclics, halogenated compounds, dioxins, and nitro compounds in the molecular mass range of 46-244 Da. The lowest amount of any substance yet detected by MRR in terms of mass is reported in this work. A theoretically unexpected finding is reported for the first time about the effect of the GC carrier gas (He, Ne, and N2) on the sensitivity of the analysis in the presence of the gas driving the supersonic jet (He, Ne, and N2) in the GC-MRR. Finally, the idea of total molecule monitoring in the GC-MRR analogous to selected ion monitoring in GC-MS is illustrated. Structural isomers and isotopologues of bromobutanes and bromonitrobenzenes are used to demonstrate this concept.
Collapse
Affiliation(s)
- M Farooq Wahab
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Saba Aslani
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - Alexander V Mikhonin
- BrightSpec, Inc., 770 Harris St., Suite 104b, Charlottesville, Virginia 22903, United States
| | - Justin L Neill
- BrightSpec, Inc., 770 Harris St., Suite 104b, Charlottesville, Virginia 22903, United States
| | - Daniel W Armstrong
- Department of Chemistry & Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States.,AZYP, LLC, Arlington, Texas 76012, United States
| |
Collapse
|
26
|
Sonstrom RE, Neill JL, Mikhonin AV, Doetzer R, Pate BH. Chiral analysis of pantolactone with molecular rotational resonance spectroscopy. Chirality 2021; 34:114-125. [PMID: 34698412 DOI: 10.1002/chir.23379] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/27/2021] [Accepted: 09/30/2021] [Indexed: 11/07/2022]
Abstract
A molecular rotational resonance spectroscopy method for measuring the enantiomeric excess of pantolactone, an intermediate in the synthesis of panthenol and pantothenic acid, is presented. The enantiomers are distinguished via complexation with a small chiral tag molecule, which produces diastereomeric complexes in the pulsed jet expansion used to inject the sample into the spectrometer. These complexes have distinct moments of inertia, so their spectra are resolved by MRR spectroscopy. Quantitative enantiomeric excess (EE) measurements are made by taking the ratio of normalized complex signal levels when a chiral tag sample of high, known EE is used, while the absolute configuration of the sample can be determined from electronic structure calculations of the complex geometries. These measurements can be performed without the need for reference samples with known enantiopurity. Two instruments were used in the analysis. A broadband, chirped-pulse spectrometer is used to perform structural characterization of the complexes. The broadband spectrometer is also used to determine the EE; however, this approach requires relatively long measurement times. A targeted MRR spectrometer is also used to demonstrate EE analysis with approximately 15-min sample-to-sample cycle time. The quantitative accuracy of the method is demonstrated by comparison with chiral gas chromatography and through the measurement of a series of reference samples prepared from mixtures of (R)-pantolactone and (S)-pantolactone samples of known EE.
Collapse
Affiliation(s)
- Reilly E Sonstrom
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
- BrightSpec, Inc., Charlottesville, Virginia, USA
| | | | | | | | - Brooks H Pate
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| |
Collapse
|
27
|
Barone V, Puzzarini C, Mancini G. Integration of theory, simulation, artificial intelligence and virtual reality: a four-pillar approach for reconciling accuracy and interpretability in computational spectroscopy. Phys Chem Chem Phys 2021; 23:17079-17096. [PMID: 34346437 DOI: 10.1039/d1cp02507d] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The established pillars of computational spectroscopy are theory and computer based simulations. Recently, artificial intelligence and virtual reality are becoming the third and fourth pillars of an integrated strategy for the investigation of complex phenomena. The main goal of the present contribution is the description of some new perspectives for computational spectroscopy, in the framework of a strategy in which computational methodologies at the state of the art, high-performance computing, artificial intelligence and virtual reality tools are integrated with the aim of improving research throughput and achieving goals otherwise not possible. Some of the key tools (e.g., continuous molecular perception model and virtual multifrequency spectrometer) and theoretical developments (e.g., non-periodic boundaries, joint variational-perturbative models) are shortly sketched and their application illustrated by means of representative case studies taken from recent work by the authors. Some of the results presented are already well beyond the state of the art in the field of computational spectroscopy, thereby also providing a proof of concept for other research fields.
Collapse
Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.
| | | | | |
Collapse
|
28
|
Barone V, Alessandrini S, Biczysko M, Cheeseman JR, Clary DC, McCoy AB, DiRisio RJ, Neese F, Melosso M, Puzzarini C. Computational molecular spectroscopy. ACTA ACUST UNITED AC 2021. [DOI: 10.1038/s43586-021-00034-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
29
|
Mishra P, Fritz SM, Herbers S, Mebel AM, Zwier TS. Gas-phase pyrolysis of trans 3-pentenenitrile: competition between direct and isomerization-mediated dissociation. Phys Chem Chem Phys 2021; 23:6462-6471. [PMID: 33729262 DOI: 10.1039/d1cp00104c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The flash pyrolysis of trans 3-pentenenitrile (3-PN, CH3-CH[double bond, length as m-dash]CH-CH2-CN) was studied by combining the results of VUV photoionization mass spectra with broadband microwave spectra recorded as a function of the temperature of the pyrolysis tube. The two separated functional groups (vinyl and nitrile) open up isomerization as an initial step in competition with unimolecular dissociation. Primary products were detected by keeping the 3-PN concentration low and limiting reaction times to the traversal time of the gas in the pyrolysis tube (∼100 μs). The reaction is quenched and products are cooled by expansion into vacuum before interrogation over the 8-18 GHz region using chirped-pulse broadband methods. 118 nm VUV photoionization of the same reaction mixture provides a means of detecting all products with ionization potentials below 10.5 eV with minimal fragmentation. These results are combined with a detailed computational investigation of the C5H7N and related potential energy surfaces, leading to a consistent picture of the unimolecular decomposition of 3-PN. Loss of two H-atoms to form a 79 amu product is proven from its microwave transitions to contain trans-Z-2,4-pentadienenitrile, while no pyridine is observed. Methyl loss, HCN loss, and breaking the central C(2)-C(3) bond all occur following isomerization of the position of the double bond, thereby opening up low-energy pathways to these decomposition channels.
Collapse
Affiliation(s)
- Piyush Mishra
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA
| | | | | | | | | |
Collapse
|
30
|
Zaleski DP, Sivaramakrishnan R, Weller HR, Seifert NA, Bross DH, Ruscic B, Moore KB, Elliott SN, Copan AV, Harding LB, Klippenstein SJ, Field RW, Prozument K. Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm. J Am Chem Soc 2021; 143:3124-3142. [PMID: 33615780 DOI: 10.1021/jacs.0c11677] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom.
Collapse
Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemistry, Colgate University, Hamilton, New York 13346, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hailey R Weller
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Nathan A Seifert
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David H Bross
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andreas V Copan
- Emmanuel College, Natural Sciences Department, Franklin Springs, Georgia 30639, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| |
Collapse
|
31
|
Li W, Quesada-Moreno MM, Pinacho P, Schnell M. Unlocking the Water Trimer Loop: Isotopic Study of Benzophenone-(H 2 O) 1-3 Clusters with Rotational Spectroscopy. Angew Chem Int Ed Engl 2021; 60:5323-5330. [PMID: 33289239 PMCID: PMC7986920 DOI: 10.1002/anie.202013899] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Indexed: 12/16/2022]
Abstract
Examined here are the structures of complexes of benzophenone microsolvated with up to three water molecules by using broadband rotational spectroscopy and the cold conditions of a molecular jet. The analysis shows that the water molecules dock sideways on benzophenone for the water monomer and dimer moieties, and they move above one of the aromatic rings when the water cluster grows to the trimer. The rotational spectra shows that the water trimer moiety in the complex adopts an open‐loop arrangement. Ab initio calculations face a dilemma of identifying the global minimum between the open loop and the closed loop, which is only solved when zero‐point vibrational energy correction is applied. An OH⋅⋅⋅π bond and a Bürgi‐Dunitz interaction between benzophenone and the water trimer are present in the cluster. This work shows the subtle balance between water–water and water–solute interactions when the solute molecule offers several different anchor sites for water molecules.
Collapse
Affiliation(s)
- Weixing Li
- Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607, Hamburg, Germany
| | | | - Pablo Pinacho
- Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607, Hamburg, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607, Hamburg, Germany.,Christian-Albrechts-Universität zu Kiel, Institute of Physical Chemistry, Max-Eyth-Str. 1, 24118, Kiel, Germany
| |
Collapse
|
32
|
Li W, Quesada‐Moreno MM, Pinacho P, Schnell M. Unlocking the Water Trimer Loop: Isotopic Study of Benzophenone‐(H
2
O)
1–3
Clusters with Rotational Spectroscopy. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Weixing Li
- Deutsches Elektronen-Synchrotron Notkestrasse 85 22607 Hamburg Germany
| | | | - Pablo Pinacho
- Deutsches Elektronen-Synchrotron Notkestrasse 85 22607 Hamburg Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron Notkestrasse 85 22607 Hamburg Germany
- Christian-Albrechts-Universität zu Kiel Institute of Physical Chemistry Max-Eyth-Str. 1 24118 Kiel Germany
| |
Collapse
|
33
|
Juanes M, Saragi RT, Enríquez L, Jaraíz M, Lesarri A. Molecular Rotation Spectrum of Tetracyclic Quinolizidines: Observation of trans-Matrine and the Elusive cis-Matrine. J Org Chem 2021; 86:1861-1867. [PMID: 33405924 DOI: 10.1021/acs.joc.0c02689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We characterized the bis-quinolizidine tetracyclic alkaloid (5S, 6S, 7R, 11R)-matrine in a supersonic jet expansion, using chirped-pulsed broadband microwave spectroscopy. Previous crystal diffraction analyses suggested 16 diastereoisomers associated with matrine's four carbon stereocenters but were inconclusive whether the lactamic nitrogen atom would additionally produce separated trans-/cis- diastereoisomers or if both species may interconvert through low potential barriers. Our experiment simultaneously detected trans- and cis-matrine through their rotational spectrum, confirming the possibility of conformational rearrangement in matrine alkaloids. The two matrine conformers mainly differ in the envelope or half-chair lactamic ring, as evidenced by the experimental rotational and nuclear quadrupole coupling parameters. Molecular orbital calculations with ab initio (MP2) and density functional methods (B3LYP-D3(BJ) and MN15) were tested against the experiment, additionally offering an estimation of the cis-/trans- barrier of 24.9-26.9 kJ mol-1. The experiment illustrates the structural potential of chirped-pulsed broadband microwave spectroscopy for high-resolution rotational studies of biomolecules in the range of 20-40 atoms.
Collapse
Affiliation(s)
- Marcos Juanes
- Departamento de Química Física y Química Inorgánica, Facultad de Ciencias-I.U. CINQUIMA, Universidad de Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain
| | - Rizalina Tama Saragi
- Departamento de Química Física y Química Inorgánica, Facultad de Ciencias-I.U. CINQUIMA, Universidad de Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain
| | - Lourdes Enríquez
- Departamento de Electrónica, ETSIT, Universidad de Valladolid, Paseo de Belén, 11, 47011 Valladolid, Spain
| | - Martín Jaraíz
- Departamento de Electrónica, ETSIT, Universidad de Valladolid, Paseo de Belén, 11, 47011 Valladolid, Spain
| | - Alberto Lesarri
- Departamento de Química Física y Química Inorgánica, Facultad de Ciencias-I.U. CINQUIMA, Universidad de Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain
| |
Collapse
|
34
|
Durif O, Capron M, Messinger JP, Benidar A, Biennier L, Bourgalais J, Canosa A, Courbe J, Garcia GA, Gil JF, Nahon L, Okumura M, Rutkowski L, Sims IR, Thiévin J, Le Picard SD. A new instrument for kinetics and branching ratio studies of gas phase collisional processes at very low temperatures. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:014102. [PMID: 33514236 DOI: 10.1063/5.0029991] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
A new instrument dedicated to the kinetic study of low-temperature gas phase neutral-neutral reactions, including clustering processes, is presented. It combines a supersonic flow reactor with vacuum ultra-violet synchrotron photoionization time-of-flight mass spectrometry. A photoion-photoelectron coincidence detection scheme has been adopted to optimize the particle counting efficiency. The characteristics of the instrument are detailed along with its capabilities illustrated through a few results obtained at low temperatures (<100 K) including a photoionization spectrum of n-butane, the detection of formic acid dimer formation, and the observation of diacetylene molecules formed by the reaction between the C2H radical and C2H2.
Collapse
Affiliation(s)
- O Durif
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - M Capron
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - J P Messinger
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - A Benidar
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - L Biennier
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - J Bourgalais
- LATMOS/IPSL, UVSQ, Université Paris-Saclay, UPMC, Univ Paris 06, CNRS, 78280 Guyancourt, France
| | - A Canosa
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - J Courbe
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - G A Garcia
- Synchrotron SOLEIL, L'orme des Merisiers, BP48 St Aubin, 91192 Gif Sur Yvette Cedex, France
| | - J F Gil
- Synchrotron SOLEIL, L'orme des Merisiers, BP48 St Aubin, 91192 Gif Sur Yvette Cedex, France
| | - L Nahon
- Synchrotron SOLEIL, L'orme des Merisiers, BP48 St Aubin, 91192 Gif Sur Yvette Cedex, France
| | - M Okumura
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - L Rutkowski
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - I R Sims
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - J Thiévin
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - S D Le Picard
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| |
Collapse
|
35
|
Lu T, Xie F, Seifert NA, Jäger W, Xu Y. Conformational landscape and intricate conformational relaxation paths of 4,4,4-trifluoro-1-butanol: Rotational spectroscopy and quantum chemical calculations. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
36
|
Domingos SR, Pérez C, Marshall MD, Leung HO, Schnell M. Assessing the performance of rotational spectroscopy in chiral analysis. Chem Sci 2020; 11:10863-10870. [PMID: 34123188 PMCID: PMC8162261 DOI: 10.1039/d0sc03752d] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023] Open
Abstract
The capabilities of rotational spectroscopy-based methods as tools to deliver accurate and precise chirality-sensitive information are still breaking ground, but their applicability in the challenging field of analytical chemistry is already clear. In this mini review, we explore the current abilities and challenges of two emergent techniques for chiral analysis based on rotational spectroscopy. For that, we will showcase the two methods (microwave 3-wave mixing and chiral tag rotational spectroscopy) while testing their performance to solve the absolute configuration and the enantiomeric excess of a blind sample containing a mixture of enantiomers of styrene oxide.
Collapse
Affiliation(s)
- Sérgio R Domingos
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
| | - Cristóbal Pérez
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
| | - Mark D Marshall
- Department of Chemistry, Amherst College P.O. Box 5000 Amherst Massachusetts 01002-5000 USA
| | - Helen O Leung
- Department of Chemistry, Amherst College P.O. Box 5000 Amherst Massachusetts 01002-5000 USA
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel Max-Eyth-Str.1 24118 Kiel Germany
| |
Collapse
|
37
|
Hearne TS, Abdelkader Khedaoui O, Hays BM, Guillaume T, Sims IR. A novel Ka-band chirped-pulse spectrometer used in the determination of pressure broadening coefficients of astrochemical molecules. J Chem Phys 2020; 153:084201. [PMID: 32872880 DOI: 10.1063/5.0017978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A novel chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer has been constructed to cover the Ka-band (26.5 GHz-40 GHz) for use in the CRESUCHIRP project, which aims to study the branching ratios of reactions at low temperatures using the chirped-pulse in uniform flow technique. The design takes advantage of recent developments in radio-frequency components, notably, high-frequency, high-power solid-state amplifiers. The spectrometer had a flatness of 5.5 dB across the spectral range, produced harmonic signals below -20 dBc, and the recorded signal scaled well to 6 × 106 averages. The new spectrometer was used to determine pressure broadening coefficients with a helium collider at room temperature for three molecules relevant to astrochemistry, applying the Voigt function to fit the magnitude of the Fourier-transformed data in the frequency domain. The pressure broadening coefficient for carbonyl sulfide was determined to be (2.45 ± 0.02) MHz mbar-1 at room temperature, which agreed well with previous measurements. Pressure broadening coefficients were also determined for multiple transitions of vinyl cyanide and benzonitrile. Additionally, the spectrometer was coupled with a cold, uniform flow from a Laval nozzle. The spectrum of vinyl cyanide was recorded in the flow, and its rotational temperature was determined to be (24 ± 11) K. This temperature agreed with a prediction of the composite temperature of the system through simulations of the experimental environment coupled with calculations of the solution to the optical Bloch equations. These results pave the way for future quantitative studies in low-temperature and high-pressure environments using CP-FTMW spectroscopy.
Collapse
Affiliation(s)
- Thomas S Hearne
- Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | | | - Brian M Hays
- Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - Théo Guillaume
- Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| | - Ian R Sims
- Univ. Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
| |
Collapse
|
38
|
Xie F, Seifert NA, Jäger W, Xu Y. Conformational Panorama and Chirality Controlled Structure–Energy Relationship in a Chiral Carboxylic Acid Dimer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Fan Xie
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| | - Nathan A. Seifert
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
- Chemical Sciences and Engineering Division Argonne National Laboratory Argonne IL 60439 USA
| | - Wolfgang Jäger
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| | - Yunjie Xu
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| |
Collapse
|
39
|
Xie F, Seifert NA, Jäger W, Xu Y. Conformational Panorama and Chirality Controlled Structure–Energy Relationship in a Chiral Carboxylic Acid Dimer. Angew Chem Int Ed Engl 2020; 59:15703-15710. [DOI: 10.1002/anie.202005685] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/27/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Fan Xie
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| | - Nathan A. Seifert
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
- Chemical Sciences and Engineering Division Argonne National Laboratory Argonne IL 60439 USA
| | - Wolfgang Jäger
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| | - Yunjie Xu
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| |
Collapse
|
40
|
Dhont G, Fontanari D, Bray C, Mouret G, Cuisset A, Hindle F, Hickson KM, Bocquet R. Characterization of the Observed Electric Field and Molecular Relaxation Times for Millimeter-Wave Chirped Pulse Instrumentation. JOURNAL OF INFRARED, MILLIMETER AND TERAHERTZ WAVES 2020; 41:1009-1021. [PMID: 32837589 PMCID: PMC7327489 DOI: 10.1007/s10762-020-00716-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
In a chirped pulse experiment, the strength of the signal level is proportional to the amplitude of the electric field, which is weaker in the millimeter-wave or submillimeter-wave region than in the microwave region. Experiments in the millimeter region thus require an optimization of the coupling between the source and the molecular system and a method to estimate the amplitude of the electric field as seen by the molecular system. We have developed an analytical model capable of reproducing the coherent transient signals obtained with a millimeter-wave chirped pulse setup operated in a monochromatic pulse mode. The fit of the model against the experimental data allowed access to the amplitude of the electric field and, as a byproduct, to the molecular relaxation times T 1 and T 2.
Collapse
Affiliation(s)
- G. Dhont
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - D. Fontanari
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - C. Bray
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - G. Mouret
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - A. Cuisset
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - F. Hindle
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| | - K. M. Hickson
- ISM, Université de Bordeaux, 351 cours de la libération, 33405 Talence cedex, France
| | - R. Bocquet
- LPCA, Université du Littoral Côte d’Opale, 189A avenue Maurice Schumann, 59140 Dunkerque, France
| |
Collapse
|
41
|
Joyce LA, Schultz DM, Sherer EC, Neill JL, Sonstrom RE, Pate BH. Direct regioisomer analysis of crude reaction mixtures via molecular rotational resonance (MRR) spectroscopy. Chem Sci 2020; 11:6332-6338. [PMID: 32953028 PMCID: PMC7472927 DOI: 10.1039/d0sc01853h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/30/2020] [Indexed: 01/05/2023] Open
Abstract
Direct analyses of crude reaction mixtures have been carried out using molecular rotational resonance (MRR) spectroscopy. Two examples are presented, a demonstration application in photocatalytic CH-arylation as well as generation of an intermediate in a natural product synthesis. In both cases, the reaction can proceed at more than one site, leading to a mixture of regioisomers that can be challenging to distinguish. MRR structural parameters were calculated for the low lying conformers for the desired compounds, and then compared to the experimental spectra of the crude mixtures to confirm the presence of these species. Next, quantitation was performed by comparing experimentally measured line intensities with simulations based on computed values for the magnitude and direction of the molecular dipole moment of each species. This identification and quantification was performed without sample purification and without isolated standards of the compounds of interest. The values obtained for MRR quantitation were in good agreement with the chromatographic values. Finally, previously unknown impurities were discovered within the photocatalytic CH-arylation work. This paper demonstrates the utility of MRR as a reaction characterization tool to simplify analytical workflows.
Collapse
Affiliation(s)
- Leo A Joyce
- Department of Process Research & Development , Merck & Co., Inc. , Rahway , NJ 07065 , USA .
| | - Danielle M Schultz
- Department of Process Research & Development , Merck & Co., Inc. , Rahway , NJ 07065 , USA .
| | - Edward C Sherer
- Department of Computational and Structural Chemistry , Merck & Co., Inc. , Rahway , NJ 07065 , USA
| | - Justin L Neill
- BrightSpec, Inc. , 770 Harris St., Suite 104b , Charlottesville , VA 22904 , USA .
| | - Reilly E Sonstrom
- Department of Chemistry , University of Virginia , McCormick Road , Charlottesville , VA 22904 , USA
| | - Brooks H Pate
- Department of Chemistry , University of Virginia , McCormick Road , Charlottesville , VA 22904 , USA
| |
Collapse
|
42
|
Zou L, Motiyenko RA, Margulès L, Alekseev EA. Millimeter-wave emission spectrometer based on direct digital synthesis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063104. [PMID: 32611015 DOI: 10.1063/5.0004461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
We present a millimeter-wave Fourier transform emission spectrometer whose design is based on the application of a direct digital synthesizer (DDS) up-converted into the Ku-band with subsequent frequency multiplication. The spectrometer covers the frequency range from 50 GHz to 110 GHz and from 150 GHz to 330 GHz. Owing to the fast frequency switching ability of the DDS in the spectrometer, the same radiation source is used both as a generator of short polarizing pulses and as a local oscillator for the heterodyne receiving system. Such a design provides intrinsically coherent reception that allows very long-term data averaging in the time domain, which improves considerably the maximum sensitivity of the spectrometer. The performances of the spectrometer including the data acquisition rate, the sensitivity, and the accuracy of line frequency measurements were tested on the rotational spectra of OCS, NH2CHO, and CH3CH2CN. We show that in the frequency range of 150-300 GHz, the maximum sensitivity of the spectrometer for a 10 min integration time is around 10-9 cm-1 (the minimal value of the absorption coefficient of detectable rotational transition) in the case of narrowband single frequency pulse excitation, and around 10-8 cm-1 in the case of broadband chirped-pulse excitation.
Collapse
Affiliation(s)
- Luyao Zou
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Roman A Motiyenko
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Laurent Margulès
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Eugen A Alekseev
- Institute of Radio Astronomy of the National Academy of Sciences of Ukraine (IRA NASU), 4, Mystetstv St., Kharkiv 61002, Ukraine
| |
Collapse
|
43
|
Pérez C, Steber AL, Temelso B, Kisiel Z, Schnell M. Water Triggers Hydrogen-Bond-Network Reshaping in the Glycoaldehyde Dimer. Angew Chem Int Ed Engl 2020; 59:8401-8405. [PMID: 32096889 PMCID: PMC7318665 DOI: 10.1002/anie.201914888] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/28/2020] [Indexed: 11/19/2022]
Abstract
Carbohydrates are ubiquitous biomolecules in nature. The vast majority of their biomolecular activity takes place in aqueous environments. Molecular reactivity and functionality are, therefore, often strongly influenced by not only interactions with equivalent counterparts, but also with the surrounding water molecules. Glycoaldehyde (Gly) represents a prototypical system to identify the relevant interactions and the balance that governs them. Here we present a broadband rotational‐spectroscopy study on the stepwise hydration of the Gly dimer with up to three water molecules. We reveal the preferred hydrogen‐bond networks formed when water molecules sequentially bond to the sugar dimer. We observe that the dimer structure and the hydrogen‐bond networks at play remarkably change upon the addition of just a single water molecule to the dimer. Further addition of water molecules does not significantly alter the observed hydrogen‐bond topologies.
Collapse
Affiliation(s)
- Cristóbal Pérez
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607, Hamburg, Germany.,Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| | - Amanda L Steber
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607, Hamburg, Germany.,Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| | - Berhane Temelso
- Division of Information Technology, College of Charleston, Charleston, SC, 29424, USA
| | - Zbigniew Kisiel
- Institute of Physics, Polish Academy of Sciences, 02-668, Warszawa, Poland
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607, Hamburg, Germany.,Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| |
Collapse
|
44
|
Pérez C, Steber AL, Temelso B, Kisiel Z, Schnell M. Water Triggers Hydrogen‐Bond‐Network Reshaping in the Glycoaldehyde Dimer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Cristóbal Pérez
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
- Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
| | - Amanda L. Steber
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
- Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
| | - Berhane Temelso
- Division of Information Technology College of Charleston Charleston SC 29424 USA
| | - Zbigniew Kisiel
- Institute of Physics Polish Academy of Sciences 02-668 Warszawa Poland
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY Notkestraße 85 22607 Hamburg Germany
- Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
| |
Collapse
|
45
|
McCarthy M, Lee KLK. Molecule Identification with Rotational Spectroscopy and Probabilistic Deep Learning. J Phys Chem A 2020; 124:3002-3017. [PMID: 32212702 DOI: 10.1021/acs.jpca.0c01376] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A proof-of-concept framework for identifying molecules of unknown elemental composition and structure using experimental rotational data and probabilistic deep learning is presented. Using a minimal set of input data determined experimentally, we describe four neural network architectures that yield information to assist in the identification of an unknown molecule. The first architecture translates spectroscopic parameters into Coulomb matrix eigenspectra as a method of recovering chemical and structural information encoded in the rotational spectrum. The eigenspectrum is subsequently used by three deep learning networks to constrain the range of stoichiometries, generate SMILES strings, and predict the most likely functional groups present in the molecule. In each model, we utilize dropout layers as an approximation to Bayesian sampling, which subsequently generates probabilistic predictions from otherwise deterministic models. These models are trained on a modestly sized theoretical dataset comprising ∼83 000 unique organic molecules (between 18 and 180 amu) optimized at the ωB97X-D/6-31+G(d) level of theory, where the theoretical uncertainties of the spectoscopic constants are well-understood and used to further augment training. Since chemical and structural properties depend strongly on molecular composition, we divided the dataset into four groups corresponding to pure hydrocarbons, oxygen-bearing species, nitrogen-bearing species, and both oxygen- and nitrogen-bearing species, training each type of network with one of these categories, thus creating "experts" within each domain of molecules. We demonstrate how these models can then be used for practical inference on four molecules and discuss both the strengths and shortcomings of our approach and the future directions these architectures can take.
Collapse
Affiliation(s)
- Michael McCarthy
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Kin Long Kelvin Lee
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| |
Collapse
|
46
|
Heim ZN, Amberger BK, Esselman BJ, Stanton JF, Woods RC, McMahon RJ. Molecular structure determination: Equilibrium structure of pyrimidine (m-C4H4N2) from rotational spectroscopy (reSE) and high-level ab initio calculation (re) agree within the uncertainty of experimental measurement. J Chem Phys 2020; 152:104303. [DOI: 10.1063/1.5144914] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zachary N. Heim
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - Brent K. Amberger
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - Brian J. Esselman
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - John F. Stanton
- Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, Florida 32611, USA
| | - R. Claude Woods
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| | - Robert J. McMahon
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
47
|
Photodissociation transition states characterized by chirped pulse millimeter wave spectroscopy. Proc Natl Acad Sci U S A 2020; 117:146-151. [PMID: 31852828 DOI: 10.1073/pnas.1911326116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 193-nm photolysis of CH2CHCN illustrates the capability of chirped-pulse Fourier transform millimeter-wave spectroscopy to characterize transition states. We investigate the HCN, HNC photofragments in highly excited vibrational states using both frequency and intensity information. Measured relative intensities of J = 1-0 rotational transition lines yield vibrational-level population distributions (VPD). These VPDs encode the properties of the parent molecule transition state at which the fragment molecule was born. A Poisson distribution formalism, based on the generalized Franck-Condon principle, is proposed as a framework for extracting information about the transition-state structure from the observed VPD. We employ the isotopologue CH2CDCN to disentangle the unimolecular 3-center DCN elimination mechanism from other pathways to HCN. Our experimental results reveal a previously unknown transition state that we tentatively associate with the HCN eliminated via a secondary, bimolecular reaction.
Collapse
|
48
|
Armstrong DW, Talebi M, Thakur N, Wahab MF, Mikhonin AV, Muckle MT, Neill JL. A Gas Chromatography‐Molecular Rotational Resonance Spectroscopy Based System of Singular Specificity. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910507] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daniel W. Armstrong
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
- AZYP, LLC Arlington TX 76012 USA
| | | | - Nimisha Thakur
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | - M. Farooq Wahab
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | | | | | | |
Collapse
|
49
|
Armstrong DW, Talebi M, Thakur N, Wahab MF, Mikhonin AV, Muckle MT, Neill JL. A Gas Chromatography‐Molecular Rotational Resonance Spectroscopy Based System of Singular Specificity. Angew Chem Int Ed Engl 2019; 59:192-196. [DOI: 10.1002/anie.201910507] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/04/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Daniel W. Armstrong
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
- AZYP, LLC Arlington TX 76012 USA
| | | | - Nimisha Thakur
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | - M. Farooq Wahab
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | | | | | | |
Collapse
|
50
|
Lampin JF, Pirali O, Buchanan ZS, Eliet S, Martin-Drumel MA, Turut J, Roy P, Hindle F, Mouret G. Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution. OPTICS LETTERS 2019; 44:4985-4988. [PMID: 31613245 DOI: 10.1364/ol.44.004985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/08/2019] [Indexed: 06/10/2023]
Abstract
A new spectrometer allowing both high resolution and broadband coverage in the terahertz (THz) domain is proposed. This instrument exploits the heterodyne technique between broadband synchrotron radiation and a quantum-cascade-laser-based molecular THz laser that acts as the local oscillator. Proof of principle for exploitation for spectroscopy is provided by the recording of molecular absorptions of hydrogen sulfide (H2S) and methanol (CH3OH) around 1.073 THz. Ultimately, the spectrometer will enable to cover the 1-4 THz region in 5 GHz windows at Doppler resolution.
Collapse
|