Structure and dynamics of methacrylamide, a computational and free-jet rotational spectroscopic study

Maris, Assimo; Melandri, Sonia; Evangelisti, Luca; Vigorito, Annalisa; Sigismondi, Silvia; Calabrese, Camilla; Usabiaga, Imanol

doi:10.1016/j.molstruc.2021.131391

Cited by 3 publications

(2 citation statements)

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“…The rotational spectra of many molecules undergoing LAMs were studied in the micron region [48], the millimeter-wave and THz ranges throughout the infrared ranges [49][50][51][52][53], and up to visible/UV [54]. Especially, far-infrared spectroscopy has significantly contributed to the understanding of LAMs [55][56][57][58][59][60][61].…”

Section: Introductionmentioning

confidence: 99%

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

2022

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Large amplitude motions (LAMs) form a fundamental phenomenon that demands the development of specific theoretical and Hamiltonian models. In recent years, along with the strong progress in instrumental techniques on high-resolution microwave spectroscopy and computational capacity in quantum chemistry, studies on LAMs have become very diverse. Larger and more complex molecular systems have been taken under investigation, ranging from series of heteroaromatic molecules from five- and six-membered rings to polycyclic-aromatic-hydrocarbon derivatives. Such systems are ideally suited to create families of molecules in which the positions and the number of LAMs can be varied, while the heteroatoms often provide a sufficient dipole moment to the systems to warrant the observation of their rotational spectra. This review will summarize three types of LAMs: internal rotation, inversion tunneling, and ring puckering, which are frequently observed in aromatic five-membered rings such as furan, thiophene, pyrrole, thiazole, and oxazole derivatives, in aromatic six-membered rings such as benzene, pyridine, and pyrimidine derivatives, and larger combined rings such as naphthalene, indole, and indan derivatives. For each molecular class, we will present the representatives and summarize the recent insights on the molecular structure and internal dynamics and how they help to advance the field of quantum mechanics.

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Section: Introductionmentioning

confidence: 99%

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

2022

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“…In this respect, rotational and ro-vibrational spectroscopies, which also allow molecular structure characterization, have been proven to be valuable tools. For instance, from the free-jet millimetre-wave spectrum of methacrylamide, 4 which is a small organic molecule with two C-C rotatable bonds (CH 3 -C(CH 2 )-CONH 2 ), two conformers (one planar and the other with non-planar doubly degenerate skeletal arrangement) were detected and their energy difference was determined (4 kJ mol À1 ). Moreover, splittings due to the torsion around both the C-C bonds were observed and analyzed with appropriate Hamiltonian models 5,6 achieving the barrier for the methyl internal rotation of both planar and non-planar conformers (10.2 and 7.4 kJ mol À1 , respectively) as well as the interconversion barrier between the two equivalent non-planar forms (3.6 kJ mol À1 ).…”

Section: Introductionmentioning

confidence: 99%

Structure and dynamics of 3′-aminoacetophenone and 4′-aminoacetophenone from rotational spectroscopy

Salvitti,

Sigismondi,

Melandri

et al. 2024

Phys. Chem. Chem. Phys.

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Skeletal Torsion Tunneling and Methyl Internal Rotation: The Coupled Large Amplitude Motions in Phenyl Acetate

et al. 2022

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The rotational spectrum of phenyl acetate, CH3COOC6H5, is measured using a free jet absorption millimeter-wave spectrometer in the range from 60 to 78 GHz and two pulsed jet Fourier transform microwave spectrometers covering a total frequency range from 2 to 26.5 GHz. The features of two large amplitude motions, the methyl group internal rotation and the skeletal torsion of the CH3COO group with respect to the phenyl ring C6H5 (tilted at about 70°), characterize the spectrum. The vibrational ground state is split into four widely spaced sublevels, labeled as A0, E0, A1, and E1, each of them with its set of rotational transitions and with additional interstate transitions. A global fit of the line frequencies of the four sublevels leads to the determination of 51 spectroscopic parameters, including the ΔEA0/A1 and ΔEE0/E1 vibrational splittings of ~36.4 and ~33.5 GHz, respectively. The V3 barrier to methyl internal rotation (~136 cm−1) and the skeletal torsion B2 barrier to the orthogonality of the two planes (~68 cm−1) are deduced.

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Structure and dynamics of methacrylamide, a computational and free-jet rotational spectroscopic study

Cited by 3 publications

References 50 publications

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

Structure and dynamics of 3′-aminoacetophenone and 4′-aminoacetophenone from rotational spectroscopy

Skeletal Torsion Tunneling and Methyl Internal Rotation: The Coupled Large Amplitude Motions in Phenyl Acetate

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