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Hartwig B, Schnell M, Suhm MA, Obenchain DA. Weak hydrogen bonding to halogens and chirality communication in propanols: Raman and microwave spectroscopy benchmark theory. Phys Chem Chem Phys 2024; 26:9432-9452. [PMID: 38446207 DOI: 10.1039/d3cp04911f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Constitutional and conformational isomers of bromopropanol are vibrationally and rotationally characterised with parallels drawn to the structural chlorine analogues. A previous microwave spectroscopic study of the chloropropanols is re-examined and all systems are explored by Raman jet spectroscopy. For bromine, the entire nuclear quadrupole coupling tensors are accurately determined and compared to their chlorine counterparts. Tensor asymmetry parameters are determined and linked with the hydrogen bond strength as indicated by the downshift of the OH-stretching frequency. The spectroscopic constants derived from the observed transitions are used as benchmarks for a large variety of electronic structure methods followed by harmonic and anharmonic rovibrational treatments. The CCSD(T) electronic structure calculations provide the best performance, in particular once anharmonic and relativistic corrections are applied or implied. Standard DFT approaches vary substantially with respect to their systematic error cancellation across the investigated species, and cost-effective compromises for the different observables are proposed.
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Affiliation(s)
- Beppo Hartwig
- Institut für Physikalische Chemie, Tammannstrasse 6, 37077 Göttingen, Germany.
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
- Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 1, 24118 Kiel, Germany
| | - Martin A Suhm
- Institut für Physikalische Chemie, Tammannstrasse 6, 37077 Göttingen, Germany.
| | - Daniel A Obenchain
- Institut für Physikalische Chemie, Tammannstrasse 6, 37077 Göttingen, Germany.
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2
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Fortenberry RC. Quantum Chemistry and Astrochemistry: A Match Made in the Heavens. J Phys Chem A 2024; 128:1555-1565. [PMID: 38381079 DOI: 10.1021/acs.jpca.3c07601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Quantum chemistry can uniquely answer astrochemical questions that no other technique can provide. Computations can be parallelized, automated, and left to run continuously providing exceptional molecular throughput that cannot be done through experimentation. Additionally, the granularity of the individual computations that are required of potential energy surfaces, reaction mechanism pathways, or other quantum chemically derived observables produces a unique mosaic that make up the larger whole. These pieces can be dissected for their individual contributions or evaluated in an ad hoc fashion for each of their roles in generating the larger whole. No other scientific approach is capable of reporting such fine-grained insights. Quantum chemistry also works from a bottom-up approach in providing properties directly from the desired molecule instead of a top-down perspective as required of experiment where molecules have to be linked to observed phenomena. Furthermore, modern quantum chemistry is well within the range of "chemical accuracy" and is approaching "spectroscopic accuracy." As such, the seemingly difficult questions asked by astrochemistry that would not be asked initially for any other application require quantum chemical reference data. While the results of quantum chemical computations are needed to interpret astrochemical observation, modeling, or laboratory experimentation, such hard questions, regardless of the original need to answer them, produce unique solutions. While questions in astrochemistry often require novel developments in and implementations of quantum chemistry as outlined herein, the applications of these solutions will stretch beyond astrochemistry and may yet impact fields much closer to Earth.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, Oxford, Mississippi 38677-1848, United States
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3
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Chen PR, Chu LK. Infrared characterization of hydrated products of glyoxal in aqueous solution. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 306:123571. [PMID: 37944380 DOI: 10.1016/j.saa.2023.123571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/19/2023] [Accepted: 10/21/2023] [Indexed: 11/12/2023]
Abstract
The simplest and most abundant dicarbonyl in the atmosphere, glyoxal ((CHO)2), and its geminal diols via stepwise hydration reactions, monohydrate (CHOCH(OH)2) and dihydrate ((HC(OH)2)2), are proposed to be responsible for the generation of atmospheric acid and the increase in aerosol viscosity. In this work, the hydrates of glyoxal were prepared by dissolving glyoxal trimer dihydrate (C6H10O8) in H2O and D2O and probed by infrared absorption spectrometry at varied temperatures. In glyoxal aqueous solution at a concentration of < 1 wt%, the monomeric dihydrate is predominant. Coupled with the predicted vibrational wavenumbers and the corresponding intensities using the B3LYP/aug-cc-pVTZ method, the intense IR bands at 1075 cm-1 and 1073 cm-1 are attributed to the C-O stretching modes of dihydrate and deuterium substituted dihydrate at the hydroxyl groups, denoted as d4-dihydrate ((HC(OD)2)2). Upon heating of the d4-dihydrate solution to cause dehydration, a new band generated at 1745 cm-1 was attributed to the C=O stretching mode of d2-monohydrate (CHOCH(OD)2). Comparing the predicted wavenumbers of glyoxal monohydrate and the observed vibrational wavenumbers of the glycolaldehyde (HCOCH2OH), the wavenumber of the C=O stretching mode of monohydrate is reasonably presumed to be 1745 ± 5 cm-1. These infrared characterizations of the glyoxal hydrates provide suitable detection windows for further investigating the roles of glyoxal and its hydrates in atmospheric and aerosol chemistry, as well as studying the relevant reaction kinetics.
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Affiliation(s)
- Pei-Rong Chen
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd, Hsinchu 300044, Taiwan
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd, Hsinchu 300044, Taiwan.
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4
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Franke PR, Stanton JF. Rotamers of Methanediol: Composite Ab Initio Predictions of Structures, Frequencies, and Rovibrational Constants. J Phys Chem A 2023; 127:924-937. [PMID: 36657011 DOI: 10.1021/acs.jpca.2c06686] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Geminal diols are known to be important intermediates in atmospheric ozonolysis and the aerosol cycle. Recently, the simplest member of this class, methanediol, was interrogated in the gas phase with infrared spectroscopy. To aid in future spectroscopic investigations of methanediol, including in the interstellar medium, we report fundamental frequencies and rovibrational constants for the two rotamers of this molecule using ab initio composite methods along with vibrational perturbation theory. Sensitivity of the predictions to the level of theory and the treatment of anharmonic resonances are carefully assessed. The OH stretching harmonic frequencies of both rotamers are particularly sensitive to the level of theory. The CH stretches of the Cs rotamer are sensitive to the treatment of anharmonic resonances with VPT2-based effective Hamiltonian models. Equilibrium bond distances and harmonic frequencies are converged conservatively to within 0.0005 Å and 3 cm-1, respectively. The effect of tunneling on the rotational constants is investigated with a 2D variational calculation, based on a relaxed hydroxyl torsional potential energy surface. Tunneling is found to be negligible in the lower energy C2 rotamer but should modify the rotational constants of the Cs rotamer on the order of MHz, giving rise to rotational line splittings of the same order. The rovibrational constants of the Cs rotamer are dominated by hydroxyl torsional effects, and here we see evidence for the breakdown of vibrational perturbation theory.
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Affiliation(s)
- Peter R Franke
- Department of Chemistry, University of Florida, Gainesville, Florida32611, United States
| | - John F Stanton
- Department of Chemistry, University of Florida, Gainesville, Florida32611, United States
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Haney OG, Westbrook BR, Santaloci TJ, Fortenberry RC. Red-Shifting the Excitation Energy of Carbonic Acid Clusters Via Nonminimum Structures. J Phys Chem A 2023; 127:489-494. [PMID: 36622286 DOI: 10.1021/acs.jpca.2c07589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Nonminimum carbonic acid clusters provide excitation energies and oscillator strengths in line with observed ice-phase UV absorptions better than traditional optimized minima. This equation-of-motion coupled cluster quantum chemical analysis on carbonic acid monomers and dimers shows that shifts to the dihedral angle for the internal heavy atoms in the monomer produce UV electronic excitations close to 200 nm with oscillator strengths that would produce observable features. This τ(OCOO) dihedral is actually a relatively floppy motion unlike what is often expected for sp2 carbons and can be distorted by 30° away from equilibrium for an energy cost of only 11 kcal/mol. As this dihedral decreases beyond 30°, the excitation energies decrease further. The oscillator strengths do, as well, but only to a point. Hence, the lower-energy distortions of τ(OCOO) are sufficient to produce structures that exhibit excitation energies and oscillator strengths that would red-shift observed spectra of carbonic acid ices away from the highest UV absorption feature at 139 nm. Such data imply that colder temperatures (20 K) in the experimental treatment of carbonic acid ices are freezing these structures out after annealing, whereas the warmer temperature experiments (80 K) are not.
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Affiliation(s)
- Olivia G Haney
- Department of Chemistry & Biochemistry, Belhaven University, Jackson, Mississippi 39212, United States
| | - Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Taylor J Santaloci
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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Jhao YJ, Chu LK. Comparing the Reactivities of Methanol and Methanediol in the Photolysis of Aqueous Nitrite Solution. J Phys Chem A 2022; 126:8233-8239. [DOI: 10.1021/acs.jpca.2c06467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Yuan-Jyun Jhao
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu300044, Taiwan
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu300044, Taiwan
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Chen YF, Chu LK. Infrared Characterization of Isotopic Analogues of Methanediol in Aqueous Solution. J Phys Chem A 2022; 126:5302-5309. [PMID: 35930362 DOI: 10.1021/acs.jpca.2c04008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dissolved methanediol in aqueous solution has been treated as the precursor for the formation of atmospheric formic acid in multiphase environments. In this work, methanediol, CH2(OH)2, and its isotopic analogues, CH2(OD)2, CD2(OH)2, and CD2(OD)2, in aqueous solution were prepared by dissolving paraformaldehyde and deuterium-substituted paraformaldehyde powders in H2O and D2O under reflux. Their infrared absorption contours of formaldehyde solutions at concentrations of <1 wt % are not dependent on the concentration, mainly referring to the characteristics of the monomeric configuration, and can be categorized into two parts. At wavenumbers >2000 cm-1, broad bands of moderate strengths were ascribed to the stretching modes of two OH or OD groups, observed at 3000-3700 and 2050-2750 cm-1, respectively. At wavenumbers of 950-1200 cm-1, the isotopic analogues of methanediols composed of CH2 moieties are featured with a singlet strong band at ca. 1030 cm-1, mainly attributed to the O-C-O stretching modes; the isotopic methanediols containing CD2 moieties manifested two intense bands at ca. 1100 and 980 cm-1, majorly enveloping the CD2 deformation and O-C-O stretching modes. The aforementioned spectral features were assigned on the basis of density functional theory, ωB97XD, with the basis set aug-cc-pVTZ and the solvent effect using the conductor-like polarizable continuum model. In addition, the predicted energetics suggested that the trans-methanediol is more stable than the cis- conformer by ca. 0.62 kcal mol-1 and majorly contributes to the infrared features. At higher concentrations of CH2(OH)2, extra bands at 920 and 1104 cm-1 appeared and were attributed to the C-O-C stretching modes of the dimeric/polymeric methanediol; that is, HO(CH2O)nH, n ≥ 2. These infrared characterizations of the isotopic analogues of methanediols provided suitable detection windows in the relevant atmospheric and aerosol reactions in the laboratory studies.
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Affiliation(s)
- Yi-Fang Chen
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300044, Taiwan
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300044, Taiwan
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Davis MC, Garrett NR, Fortenberry RC. Confirmation of gaseous methanediol from state-of-the-art theoretical rovibrational characterization. Phys Chem Chem Phys 2022; 24:18552-18558. [PMID: 35904881 DOI: 10.1039/d2cp02076a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-level rovibrational characterization of methanediol, the simplest geminal diol, using state-of-the-art, purely ab initio techniques unequivocally confirms previously reported gas phase preparation of this simplest geminal diol in its C2 conformation. The F12-TZ-cCR and F12-DZ-cCR quartic force fields (QFFs) utilized in this work are among the largest coupled cluster-based anharmonic frequencies computed to date, and they match the experimental band origins of the spectral features in the 980-1100 cm-1 range to within 3 cm-1, representing a significant improvement over previous studies. The simulated spectrum also matches the experimental spectrum in the strong Q branch feature and qualitative shape of the 980-1100 cm-1 region. Additionally, the full set of rotational constants, anharmonic vibrational frequencies, and quartic and sextic distortion constants are provided for both the lowest energy C2 conformer as well as the slightly higher Cs conformer. Several vibrational modes have intensities of 60 km mol-1 or higher, facilitating potential astronomical or atmospheric detection of methanediol or further identification in laboratory work especially now that gas phase synthesis of this molecule has been established.
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Affiliation(s)
- Megan C Davis
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS, 38677-1848, USA.
| | - Noah R Garrett
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS, 38677-1848, USA.
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, MS, 38677-1848, USA.
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Abstract
The simplest geminal diol CH2(OH)2 serves as an important precursor to form atmospheric formic acid. CH2(OH)2 vapour can be generated by the evaporation of an aqueous formaldehyde solution, prepared by dissolving paraformaldehyde under reflux. Its rovibrational feature at 980-1100 cm-1 is consistent with the simulation and free of the intense interferences of H2O and CH2O.
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Affiliation(s)
- Yi-Fang Chen
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd, Hsinchu 300044, Taiwan.
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd, Hsinchu 300044, Taiwan.
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Fischer TLL, Bödecker MADI, Zehnacker A, Mata RA, Suhm MA. Setting up the HyDRA blind challenge for the microhydration of organic molecules. Phys Chem Chem Phys 2022; 24:11442-11454. [DOI: 10.1039/d2cp01119k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The procedure leading to the first HyDRA blind challenge for the prediction of water donor stretching vibrations in monohydrates of organic molecules is described. A training set of 10 monohydrates...
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Burevschi E, Peña I, Sanz ME. Geminal Diol Formation from the Interaction of a Ketone with Water in the Gas Phase: Structure and Reactivity of Cyclooctanone-(H 2O) 1,2 Clusters. J Phys Chem Lett 2021; 12:12419-12425. [PMID: 34939809 DOI: 10.1021/acs.jpclett.1c03493] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The hydration of ketones is known to occur in condensed phases, but it is not considered to be favorable in the gas phase due to restricted water content. We report the first evidence of geminal diol formation upon ketone hydration in the gas phase, obtained through the investigation of the interactions of cyclooctanone with water using broadband rotational spectroscopy. Oxygen-atom exchange between water and cyclooctanone was observed for two isomers of cyclooctanone-H2O and two isomers of cyclooctanone-(H2O)2. All complexes were unambiguously identified from the analysis of the rotational spectrum of the parent species and all their 13C and 18O isotopologues, and their heavy-atom substitution and effective structures were determined as well as their binding interactions. The production of gem-diols from gas-phase hydration of ketones has implications for atmospheric chemistry and opens a new channel for secondary aerosol formation.
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Affiliation(s)
| | - Isabel Peña
- Department of Chemistry, King's College London, London SE1 1DB, U.K
| | - M Eugenia Sanz
- Department of Chemistry, King's College London, London SE1 1DB, U.K
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