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Styers WH, Zdanovskaia MA, Esselman BJ, Owen AN, Kougias SM, Billinghurst BE, Zhao J, McMahon RJ, Woods RC. Millimeter-Wave and High-Resolution Infrared Spectroscopy of 3-Furonitrile. J Phys Chem A 2024; 128:6084-6097. [PMID: 38916202 DOI: 10.1021/acs.jpca.4c03093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
The rotational spectrum of 3-furonitrile has been collected from 85 to 500 GHz, spanning the most intense rotational transitions observable at room temperature. The large dipole moment imparted by the nitrile substituent confers substantial intensity to the rotational spectrum, enabling the observation of over 5600 new rotational transitions. Combined with previously published transitions, the available data set was least-squares fit to partial-octic, distorted-rotor A- and S-reduced Hamiltonian models with low statistical uncertainty (σfit < 0.031 MHz) for the ground vibrational state. Similar to its isomer 2-furonitrile, the two lowest-energy vibrationally excited states of 3-furonitrile (ν17, ν24), which correspond to the in-plane and out-of-plane nitrile bending vibrations, form an a- and b-axis Coriolis-coupled dyad. Rotationally resolved infrared transitions (30-600 cm-1) and over 4200 pure rotational transitions for both ν17 and ν24 were fit to a partial-octic, Coriolis-coupled, two-state Hamiltonian with low statistical uncertainty (σfit rot < 0.045 MHz, σfit IR < 6.1 MHz). The least-squares fitting of these vibrationally excited states provides their accurate and precise vibrational frequencies (ν17 = 168.193 164 8 (67) cm-1 and ν24 = 169.635 831 5 (77) cm-1) and seven Coriolis-coupling terms (Ga, GaJ, GaK, Fbc, FbcK, Gb, and Fac). The two fundamental states exhibit a notably small energy gap (1.442 667 (10) cm-1) and an inversion of the relative energies of ν17 and ν24 compared to those of the isomer 2-furonitrile. The rotational frequencies and spectroscopic constants of 3-furonitrile that we present herein provide a sufficient basis for conducting radioastronomical searches for this molecule across the majority of the frequency range available to current radiotelescopes.
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Affiliation(s)
- William H Styers
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Maria A Zdanovskaia
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Brian J Esselman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Andrew N Owen
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Samuel M Kougias
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Brant E Billinghurst
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Jianbao Zhao
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Robert J McMahon
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - R Claude Woods
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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2
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Alessandrini S, Melosso M, Bizzocchi L, Barone V, Puzzarini C. The Semiexperimental Approach at Work: Equilibrium Structure of Radical Species. J Phys Chem A 2024; 128:5833-5855. [PMID: 38991181 DOI: 10.1021/acs.jpca.4c01758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The so-called semiexperimental (SE) approach is a powerful technique for obtaining highly accurate equilibrium structures for isolated systems. This Featured Article describes its extension to open-shell species, thus providing the first systematic investigation on radical equilibrium geometries to be used for benchmarking purposes. The small yet significant database obtained demonstrates that there is no reduction in accuracy when moving from closed-shell species to radicals. We also provide an extension of the applicability of the SE approach to medium-/large-sized radicals by exploiting the so-called "Lego-brick" approach, which is based on the assumption that a molecular system can be seen as formed by smaller fragments for which the SE equilibrium structure is available. In this Featured Article we show that this model can be successfully applied also to open-shell species.
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Affiliation(s)
- Silvia Alessandrini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Mattia Melosso
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Luca Bizzocchi
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | | | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
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Lv D, Sundelin D, Maris A, Evangelisti L, Geppert WD, Melandri S. Intermolecular Interactions between Aldehydes and Alcohols: Conformational Equilibrium and Rotational Spectra of Acrolein-Methanol Complex. Molecules 2024; 29:3444. [PMID: 39124850 PMCID: PMC11313379 DOI: 10.3390/molecules29153444] [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: 06/07/2024] [Revised: 07/19/2024] [Accepted: 07/19/2024] [Indexed: 08/12/2024] Open
Abstract
The rotational spectra of the 1:1 complex formed by acrolein and methanol and its deuterated isotopologues have been analyzed. Two stable conformations in which two hydrogen bonds between the two moieties are formed were detected. The rotational lines show a hyperfine structure due to the methyl group internal rotation in the complex and the V3 barriers hindering the motion were determined as 2.629(5) kJ mol-1 and 2.722(5) kJ mol-1 for the two conformations, respectively. Quantum mechanical calculations at the MP2/aug-cc-pVTZ level and comprehensive analysis of the intermolecular interactions, utilizing NCI and SAPT approaches, highlight the driving forces of the interactions and allow the determination of the binding energies of complex formation.
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Affiliation(s)
- Dingding Lv
- Dipartimento di Chimica “G. Ciamician” Università di Bologna, Via Selmi 2, I-40126 Bologna, Italy
| | - David Sundelin
- Fysikum, Stockholm University, Roslagstullsbacken 21, 106 91 Stockholm, Sweden;
| | - Assimo Maris
- Dipartimento di Chimica “G. Ciamician” Università di Bologna, Via Selmi 2, I-40126 Bologna, Italy
| | - Luca Evangelisti
- Dipartimento di Chimica “G. Ciamician” Università di Bologna, Via Selmi 2, I-40126 Bologna, Italy
| | | | - Sonia Melandri
- Dipartimento di Chimica “G. Ciamician” Università di Bologna, Via Selmi 2, I-40126 Bologna, Italy
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Di Grande S, Barone V. Toward Accurate Quantum Chemical Methods for Molecules of Increasing Dimension: The New Family of Pisa Composite Schemes. J Phys Chem A 2024; 128:4886-4900. [PMID: 38847454 DOI: 10.1021/acs.jpca.4c01673] [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 new versions of the Pisa composite scheme introduced in the present paper are based on the careful selection of different quantum chemical models for energies, geometries, and vibrational frequencies, with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, the computation of accurate electronic energies has been further improved introducing more reliable complete basis set extrapolations and estimation of core-valence correlation, together with improved basis sets for third-row atoms. Furthermore, the reduced-cost frozen natural orbital (FNO) model has been introduced and validated for large molecules. Accurate molecular structures can be obtained avoiding complete basis set extrapolation and evaluating core-valence correlation at the MP2 level. Unfortunately, analytical gradients are not available for the FNO version of the model. Therefore, for large molecules, an accurate reduced-cost alternative is offered by evaluation of valence contributions with a double-hybrid functional in conjunction with the same MP2 contribution for core-valence correlation or by means of a one-parameter approximation. The same double-hybrid functional and basis set are employed to evaluate zero-point energies and partition functions. After the validation of the new models for small systems, a panel of molecular bricks of life has been used to analyze their performances for problems of current fundamental or technological interest. The fully black-box implementation of the computational workflow paves the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by experimentally oriented researchers.
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Affiliation(s)
- Silvia Di Grande
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
- Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy
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Silva WGDP, van Wijngaarden J. Disentangling the Conformational Space and Structural Preferences of Tetrahydrofurfuryl Alcohol Using Rotational Spectroscopy and Computational Chemistry. Chemphyschem 2024; 25:e202400298. [PMID: 38637291 DOI: 10.1002/cphc.202400298] [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: 03/17/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 04/20/2024]
Abstract
The influence of the hydroxymethyl (CH2OH) group on the tetrahydrofuran (THF) ring structure was investigated by disentangling the gas phase conformational landscape of the sugar analogue tetrahydrofurfuryl alcohol (THFA). By combining rotational spectroscopy (6-20 GHz) and quantum chemical calculations, transitions corresponding to two stable conformers of THFA and their 13C isotopologues were observed and assigned in the rotational spectrum. The positions of the C atoms were precisely determined to unambiguously distinguish between nearly isoenergetic pairs of conformers that differ in their ring configurations: envelope (E) versus twist (T). The rotational spectrum confirms that the E ring geometry is favoured when the CH2OH fragment lies gauche (-) to the THF backbone (OCCO ~-60°) whereas the T form is more stable for the gauche (+) alignment of the substituent (OCCO ~+60°). The observed spectral intensities suggest that conformational relaxation of the THF geometry (E↔T) to the more stable form readily occurs within the pairs of g- and g+ conformers which is consistent with the low barriers (1.5-1.7 kJ mol-1) for conversion determined via transition state calculations. Insights into the intramolecular hydrogen bonding and other weak interactions stabilizing the lowest energy structures of THFA were derived and rationalized using non-covalent interaction analyses.
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Affiliation(s)
- Weslley G D P Silva
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937, Köln, Germany
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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.
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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.
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Barone V. Quantum chemistry meets high-resolution spectroscopy for characterizing the molecular bricks of life in the gas-phase. Phys Chem Chem Phys 2024; 26:5802-5821. [PMID: 38099409 DOI: 10.1039/d3cp05169b] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Computation of accurate geometrical structures and spectroscopic properties of large flexible molecules in the gas-phase is tackled at an affordable cost using a general exploration/exploitation strategy. The most distinctive feature of the approach is the careful selection of different quantum chemical models for energies, geometries and vibrational frequencies with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, a composite wave-function method is used for energies, whereas a double-hybrid functional (with the addition of core-valence correlation) is employed for geometries and harmonic frequencies and a cheaper hybrid functional for anharmonic contributions. A thorough benchmark based on a wide range of prototypical molecular bricks of life shows that the proposed strategy is close to the accuracy of state-of-the-art composite wave-function methods, and is applicable to much larger systems. A freely available web-utility post-processes the geometries optimized by standard electronic structure codes paving the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules by experimentally-oriented researchers.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy.
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Barone V, Lazzari F. Hunting for Complex Organic Molecules in the Interstellar Medium: The Role of Accurate Low-Cost Theoretical Geometries and Rotational Constants. J Phys Chem A 2023; 127:10517-10527. [PMID: 38033327 PMCID: PMC10726368 DOI: 10.1021/acs.jpca.3c06649] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023]
Abstract
A new approach to computation at affordable cost of accurate geometrical structures and rotational constants for medium-sized molecules in the gas phase is further improved and applied to a large panel of interstellar complex organic molecules. The most distinctive feature of the new model is the effective inclusion of core-valence correlation and vibrational averaging effects in the framework of density functional theory (DFT). In particular, a double-hybrid functional in conjunction with a quadruple-ζ valence/triple-ζ polarization basis set is employed for geometry optimizations, whereas a cheaper hybrid functional in conjunction with a split-valence basis set is used for the evaluation of vibrational corrections. A thorough benchmark based on a wide range of prototypical systems shows that the new scheme approaches the accuracy of state-of-the-art wave function methods with the computational cost of the standard methods (DFT or MP2) routinely employed in the interpretation of microwave spectra. Since the whole computational workflow involves the postprocessing of the output of standard electronic structure codes by a new freely available web utility, the way is paved for the accurate yet not prohibitively expensive study of medium- to large-sized molecules also by nonspecialists.
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Affiliation(s)
- Vincenzo Barone
- Scuola Normale Superiore, di Pisa, Piazza dei Cavalieri 7, Pisa 56125, Italy
| | - Federico Lazzari
- Scuola Normale Superiore, di Pisa, Piazza dei Cavalieri 7, Pisa 56125, Italy
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