Infrared-Induced Rotamerization of Oxalic Acid Monomer in Argon Matrix

Maçôas, Ermelinda; Fausto, Rui; Pettersson, Mika; Khriachtchev, Leonid; Räsänen, Markku

doi:10.1021/jp000634s

Cited by 70 publications

(69 citation statements)

References 20 publications

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“…The fast dark decay of both C t and C g ( conformers is due to a phononassisted tunneling process, which has been shown to be common for internal rotation around the C-O bond in simple carboxylic acids such as formic and acetic acids. 3,7 For the deuterated isotopologue (PA-OD), the C t and T g ( conformers produced by excitation of the T t form are quite stable at 8 K. In fact, when compared to PA-OH, the C t to T t conversion by tunneling slows down by ca. 4 orders of magnitude.…”

Section: Computational Resultsmentioning

confidence: 99%

“…The proposed stepwise mechanism is consistent with the model for the dark C f T tunneling decay in formic and acetic acids from the torsional ground state of the cis conformer to a vibrationally excited state of the trans form. 3,7 …”

Section: Computational Resultsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] These studies have been mainly motivated by our interest in the conformational dynamics of the carboxylic group as a way to understand the process of intramolecular vibrational energy relaxation, which plays an important role in molecular reactivity. Interestingly, the photolysis of formic acid was shown to be conformationally dependent, being acknowledged as one of the first clear cases of optical control of chemical reactivity.…”

Section: Introductionmentioning

confidence: 99%

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Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

et al. 2005

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The conformational system of propionic acid (CH 3 CH 2 COOH) is studied in solid argon. It is predicted by the ab initio calculations that this molecule has four stable conformers. These four structures are denoted T t , T g ( , C t , and C g ( , and they differ by the arrangement around the C-O and C R -C bonds. The ground-state T t conformer is the only form present at 8 K after deposition of an argon matrix containing propionic acid. For the CH 3 CH 2 COOH and CH 3 CH 2 COOD isotopologues, narrow-band excitation of the first hydroxyl stretching overtone of the conformational ground state promotes the C R -C and C-O internal rotations producing the T g ( and C t conformers, respectively. A subsequent vibrational excitation of the produced T g ( form induces its conversion to the C g ( conformer by rotation around the C-O bond. In the dark, all of the produced conformers decay to the conformational ground state at different rates. The decay kinetics and its temperature dependence allow the identification of the conformers by IR absorption spectroscopy, which is supported by ab initio calculations of their vibrational spectra. For the CH 3 CH 2 COOD isotopologue, the excitation of molecules isolated in different matrix sites results in site-dependent photoisomerization rates for the C R -C and C-O internal rotations, which also confirm the identification of the photoproducts.

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Section: Computational Resultsmentioning

confidence: 99%

Section: Computational Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

et al. 2005

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“…These calculations are relatively inexpensive in computational terms and have been proven to yield reasonable structural data for similar compounds. 8,18 We then used the HF/6-31G(d) calculations as a first estimate to the higher-level MP2 and DFT calculations.…”

Section: Resultsmentioning

confidence: 99%

“…17 The calculated frequencies (B3LYP) were then scaled with the use of a single scale factor (0.9614). 18 …”

Section: Experimental and Computational Detailsmentioning

confidence: 99%

Conformational Analysis and Near-Infrared-Induced Rotamerization of Malonic Acid in an Argon Matrix

Maçôas¹,

Fausto²,

Lundell³

et al. 2000

J. Phys. Chem. A

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Relative energies and vibrational spectra of the conformational states of a malonic acid monomer (HOOCCH 2 -COOH) were calculated using various levels of approximation [Hartree-Fock (HF), Møller-Plesset to second order (MP2), and B3LYP density functional theory (DFT)]. The calculations predict the existence of six different conformers according to skeletal C-C bond and O-H bond rotation. Three conformers are found with energies close enough to enable their spectroscopic observation. The lowest-energy conformer (I) shows a nearly planar structure with an OH‚‚‚OdC intramolecular hydrogen bond closing a six-member OdC-CH 2 -C-O-H ring. The second-and third-lower energy conformers (II and III) differ from the conformational ground state by less than 5 kJ mol -1 . Conformers II and III adopt a cis arrangement around the C-O bonds: conformer II exhibits the two carbonyl bonds in a nearly orthogonal arrangement, with one carboxylic group in the plane containing the carbon atoms, whereas in conformer III (C 2 symmetry), the carbonyl bonds make a dihedral angle of ca. 120°, and both carboxylic groups are placed out of the plane containing the skeletal carbons. Their relative energy is predicted by the highest-level calculations to be ca. 1 kJ mol -1 . The theoretical predictions agree with the analysis of the infrared spectra of monomeric malonic acid isolated in a solid argon matrix, where the presence of the three above-mentioned conformers was unequivocally identified. Narrowband tunable irradiation in the near-infrared region was found to promote efficiently the interconversion between the experimentally observed conformers.

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Intramolecular Hydrogen Bonding: Shaping Conformers' Structure and Stability

Ildız¹,

Fausto²

2022

Spectroscopy and Computation of Hydrogen‐Bonded Systems

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Infrared-Induced Rotamerization of Oxalic Acid Monomer in Argon Matrix

Cited by 70 publications

References 20 publications

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon

Conformational Analysis and Near-Infrared-Induced Rotamerization of Malonic Acid in an Argon Matrix

Intramolecular Hydrogen Bonding: Shaping Conformers' Structure and Stability

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