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Darugar V, Vakili M, Tayyari SF, Kamounah FS. Validation of potential energy distribution by VEDA in vibrational assignment some of β-diketones; comparison of theoretical predictions and experimental vibration shifts upon deutration. J Mol Graph Model 2021; 107:107976. [PMID: 34192656 DOI: 10.1016/j.jmgm.2021.107976] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 06/20/2021] [Accepted: 06/22/2021] [Indexed: 11/27/2022]
Abstract
The harmonic vibrational frequencies of the cis-enol forms of some of β-diketones with different substitution in beta position, vis. H, CH3, and Ph ring, as the symmetric and asymmetric molecules, were calculated using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level of theory. The results of DFT calculations were used to obtain the potential energy distribution (PED) by VEDA software. The PED results compared with the Gauss View animation, as our reassignments, and the experimental IR shifts upon deuteration of hydrogen in the OH and CHα. According to our study, the PED contributions, Gauss View animation and observed shifts show similar results for most of the bands which are not coupled with the OH and/or CHα bending, such as asymmetric and symmetric CH3 stretching and in-plane deformations, CH3 rocking vibrations and 8a, 19b, 9a, 15, 18a, and 12 motions of the phenyl ring. The largest discrepancies were observed in the 1700-1000 cm-1 region, likely due to the coupling with the OH and CHα in-plane bending vibrations, such as νaC = C-C = Ο, νsC = C-C = Ο and δOH. Furthermore, the calculated PED contributions by VEDA software do not well define the vibrational contributions to those groups in the molecule that are directly involved in the intramolecular hydrogen bond and the observed failure of the VEDA procedure is possibly due to inappropriateness of the default options.
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Affiliation(s)
- Vahidreza Darugar
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Iran
| | - Mohammad Vakili
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Iran.
| | | | - Fadhil S Kamounah
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen Ø, Denmark
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2
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Berenbeim JA, Wong NGK, Cockett MCR, Berden G, Oomens J, Rijs AM, Dessent CEH. Unravelling the Keto-Enol Tautomer Dependent Photochemistry and Degradation Pathways of the Protonated UVA Filter Avobenzone. J Phys Chem A 2020; 124:2919-2930. [PMID: 32208697 PMCID: PMC7168606 DOI: 10.1021/acs.jpca.0c01295] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Avobenzone (AB) is
a widely used UVA filter known to undergo irreversible
photodegradation. Here, we investigate the detailed pathways by which
AB photodegrades by applying UV laser-interfaced mass spectrometry
to protonated AB ions. Gas-phase infrared multiple-photon dissociation
(IRMPD) spectra obtained with the free electron laser for infrared
experiments, FELIX, (600–1800 cm–1) are also
presented to confirm the geometric structures. The UV gas-phase absorption
spectrum (2.5–5 eV) of protonated AB contains bands that correspond
to selective excitation of either the enol or diketo forms, allowing
us to probe the resulting, tautomer-dependent photochemistry. Numerous
photofragments (i.e., photodegradants) are directly identified for
the first time, with m/z 135 and
161 dominating, and m/z 146 and
177 also appearing prominently. Analysis of the production spectra
of these photofragments reveals that that strong enol to keto photoisomerism
is occurring, and that protonation significantly disrupts the stability
of the enol (UVA active) tautomer. Close comparison of fragment ion
yields with the TD-DFT-calculated absorption spectra give detailed
information on the location and identity of the dissociative excited
state surfaces, and thus provide new insight into the photodegradation
pathways of avobenzone, and photoisomerization of the wider class
of β-diketone containing molecules.
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Affiliation(s)
- Jacob A Berenbeim
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Natalie G K Wong
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Martin C R Cockett
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Anouk M Rijs
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
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3
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Milovanović B, Stanković IM, Petković M, Etinski M. Elucidating Solvent Effects on Strong Intramolecular Hydrogen Bond: DFT-MD Study of Dibenzoylmethane in Methanol Solution. Chemphyschem 2019; 20:2852-2859. [PMID: 31544323 DOI: 10.1002/cphc.201900704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/31/2019] [Indexed: 11/10/2022]
Abstract
The dynamic aspect of solvation plays a crucial role in determining properties of strong intramolecular hydrogen bonds since solvent fluctuations modify instantaneous hydrogen-bonded proton transfer barriers. Previous studies pointed out that solvent-solute interactions in the first solvation shell govern the position of the proton but the ability of the electric field due to other solvent molecules to localize the proton remains an important issue. In this work, we examine the structure of the O-H⋅⋅⋅O intramolecular hydrogen bond of dibenzoylmethane in methanol solution by employing density functional theory-based molecular dynamics and quantum chemical calculations. Our computations showed that homogeneous electric fields with intensities corresponding to those found in polar solvents are able to considerably alter the proton transfer barrier height in the gas phase. In methanol solution, the proton position is correlated with the difference in electrostatic potentials on the oxygen atoms of dibenzoylmethane even when dibenzoylmethane-methanol hydrogen bonding is lacking. On a timescale of our simulation, the hydrogen bonding and solvent electrostatics tend to localize the proton on different oxygen atoms. These findings provide an insight into the importance of the solvent electric field on the structure of a strong intramolecular hydrogen bond.
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Affiliation(s)
- Branislav Milovanović
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
| | | | - Milena Petković
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Mihajlo Etinski
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
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4
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Kojić M, Lyskov I, Milovanović B, Marian CM, Etinski M. The UVA response of enolic dibenzoylmethane: beyond the static approach. Photochem Photobiol Sci 2019; 18:1324-1332. [DOI: 10.1039/c9pp00005d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nπ* and ππ* states of dibenzoylmethane are vibronically coupled and their crossing occurs during the excited-state intramolecular proton transfer.
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Affiliation(s)
- Marko Kojić
- Faculty of Physical Chemistry
- University of Belgrade
- 11000 Belgrade
- Serbia
| | - Igor Lyskov
- Chemical and Quantum Physics Group
- ARC Centre of Excellence in Exciton Science
- School of Science
- RMIT University
- Melbourne
| | | | - Christel M. Marian
- Institute of Theoretical and Computational Chemistry
- Heinrich Heine University Düsseldorf
- D-40225 Düsseldorf
- Germany
| | - Mihajlo Etinski
- Faculty of Physical Chemistry
- University of Belgrade
- 11000 Belgrade
- Serbia
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5
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Xie F, Ng X, Seifert NA, Thomas J, Jäger W, Xu Y. Rotational spectroscopy of chiral tetrahydro-2-furoic acid: Conformational landscape, conversion, and abundances. J Chem Phys 2018; 149:224306. [DOI: 10.1063/1.5063683] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Fan Xie
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Xiaoqian Ng
- 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
| | - Javix Thomas
- 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
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6
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Etinski M, Ensing B. Puzzle of the Intramolecular Hydrogen Bond of Dibenzoylmethane Resolved by Molecular Dynamics Simulations. J Phys Chem A 2018; 122:5945-5954. [DOI: 10.1021/acs.jpca.8b01930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mihajlo Etinski
- Faculty of Physical Chemistry, University of Belgrade Studentski trg 12-16 11000 Belgrade, Serbia
| | - Bernd Ensing
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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7
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Thomas J, Mariona E, Xu Y. Rotational spectra of two six-membered heterocyclic N-methyl-piperidinol compounds: Conformations by OH rotation, N-methyl inversion, and ring puckering. J Chem Phys 2017; 146:104303. [DOI: 10.1063/1.4977895] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Javix Thomas
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Eric Mariona
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
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8
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Schnitzler EG, Zenchyzen BLM, Jäger W. Rotational spectroscopy of the atmospheric photo-oxidation product o-toluic acid and its monohydrate. Phys Chem Chem Phys 2016; 18:448-57. [PMID: 26616640 DOI: 10.1039/c5cp06073g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
o-Toluic acid, a photo-oxidation product in the atmosphere, and its monohydrate were characterized in the gas phase by pure rotational spectroscopy. High-resolution spectra were measured in the range of 5-14 Hz using a cavity-based molecular beam Fourier-transform microwave spectrometer. Possible conformers were identified computationally, at the MP2/6-311++G(2df,2pd) level of theory. For both species, one conformer was identified experimentally, and no methyl internal rotation splittings were observed, indicative of relatively high barriers to rotation. In the monomer, rocking of the carboxylic acid group is a large amplitude motion, characterized by a symmetrical double-well potential. This and other low-lying out-of-plane vibrations contribute to a significant (methyl top-corrected) inertial defect (-1.09 amu Å(2)). In the monohydrate, wagging of the free hydrogen atom of water is a second large amplitude motion, so the average structure is planar. As a result, no c-type transitions were observed. Water tunneling splittings were not observed, because the water rotation coordinate is characterized by an asymmetrical double-well potential. Since the minima are not degenerate, tunneling is precluded. Furthermore, a concerted tunneling path involving simultaneous rotation of the water moiety and rocking of the carboxylic acid group is precluded, because the hilltop along this coordinate is a virtual, rather than a real, saddle-point. Inter- and intramolecular non-covalent bonding is discussed in terms of the quantum theory of atoms in molecules. The percentage of o-toluic acid hydrated in the atmosphere is estimated to be about 0.1% using statistical thermodynamics.
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Affiliation(s)
- Elijah G Schnitzler
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
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Kojić M, Petković M, Etinski M. A new insight into the photochemistry of avobenzone in gas phase and acetonitrile from ab initio calculations. Phys Chem Chem Phys 2016; 18:22168-78. [DOI: 10.1039/c6cp03533g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Coupled cluster based calculations on the ground and excited states of avobenzone provide mechanistic understanding of formation of transient tautomers upon photoexcitation of the chelated enol form.
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Affiliation(s)
- Marko Kojić
- Faculty of Physical Chemistry
- University of Belgrade
- 11000 Belgrade
- Serbia
| | - Milena Petković
- Faculty of Physical Chemistry
- University of Belgrade
- 11000 Belgrade
- Serbia
| | - Mihajlo Etinski
- Faculty of Physical Chemistry
- University of Belgrade
- 11000 Belgrade
- Serbia
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10
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Schnitzler EG, Poopari MR, Xu Y, Jäger W. Rotational spectroscopy of methyl benzoylformate and methyl mandelate: structure and internal dynamics of a model reactant and product of enantioselective reduction. Phys Chem Chem Phys 2015; 17:21942-9. [PMID: 26234934 DOI: 10.1039/c5cp03114a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pure rotational spectra of a prototypical prochiral ester, methyl benzoylformate (MBF), and the product of its enantioselective reduction, (R)-(-)-methyl mandelate (MM), were measured in the range of 5-16 GHz, using a cavity-based molecular beam Fourier-transform microwave spectrometer. Potential conformers were located using density functional theory calculations, and one conformer of each species was identified experimentally. The minimum energy conformer of MBF, in which the ester group is in a Z orientation, was observed for the first time. Based on an atoms-in-molecules analysis, MBF contains a weak CH···O=C hydrogen bond between the carbonyl oxygen atom of the ester group and the nearest hydrogen atom of the aromatic ring. In the minimum energy conformer of MM, the ester group is oriented to accommodate a hydrogen bond between the hydrogen atom of the hydroxyl group and the carbonyl oxygen atom (OH···O=C), rather than the sp(3) oxygen atom (OH···O-C). For both species, splittings of the rotational transitions were observed, which are attributed to methyl internal rotation, and the orientations and barrier heights of the methyl tops were determined precisely. The barrier heights for MBF and MM are 4.60(2) and 4.54(3) kJ mol(-1), respectively, which are consistent with values predicted by high-level wavefunction-based calculations. On the basis of an atoms-in-molecules analysis, we propose that destabilization of the sp(3) oxygen atom of the ester group most directly dictates the barrier height.
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Affiliation(s)
- Elijah G Schnitzler
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
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11
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Thomas J, Liu X, Jäger W, Xu Y. Unusual H-Bond Topology and Bifurcated H-bonds in the 2-Fluoroethanol Trimer. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201505934] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Thomas J, Liu X, Jäger W, Xu Y. Unusual H-Bond Topology and Bifurcated H-bonds in the 2-Fluoroethanol Trimer. Angew Chem Int Ed Engl 2015; 54:11711-5. [PMID: 26276699 DOI: 10.1002/anie.201505934] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Indexed: 11/06/2022]
Abstract
By using a combination of rotational spectroscopy and ab initio calculations, an unusual H-bond topology was revealed for the 2-fluoroethanol trimer. The trimer exhibits a strong heterochiral preference and adopts an open OH⋅⋅⋅OH H-bond topology while utilizing two types of bifurcated H-bonds involving organic fluorine. This is in stark contrast to the cyclic OH⋅⋅⋅OH H-bond topology adopted by trimers of water and other simple alcohols. The strengths of different H-bonds in the trimer were analyzed by using the quantum theory of atoms in molecules. The study showcases a remarkable example of a chirality-induced switch in H-bond topology in a simple transient chiral fluoroalcohol. It provides important insight into the H-bond topologies of small fluoroalcohol aggregates, which are proposed to play a key role in protein folding and in enantioselective reactions and separations where fluoroalcohols serve as a (co)solvent.
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Affiliation(s)
- Javix Thomas
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada)
| | - Xunchen Liu
- School of Mechanical Engineering, Shanghai Jiao Tong University, No.800 Dong Chuan Road, Shanghai, 200240 (P.R. China)
| | - 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).
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