Rotation-tunneling spectra and barriers of isotopologues of 2,2,2-trifluoroethanol and 2,2,3,3,3-pentafluoropropanol

Ma, Jiarui; Insausti, Aran; Mort, Alex N.; Xu, Yunjie

doi:10.1016/j.jms.2022.111687

Cited by 3 publications

(14 citation statements)

References 35 publications

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“…TFE has three possible conformations: gauche+ , trans , and gauche – , corresponding to a dihedral angle τ(CCOH) of +60°, 180°, and −60°, respectively . While the tunnelling splitting between gauche+ and gauche – conformations of the TFE monomer was investigated experimentally, , trans TFE was shown to be either not a minimum or an extremely shallow minimum which does not support a zero-point energy (ZPE) level . Efforts to probe how intermolecular interactions with another (transient) chiral molecule or with water would influence the relative stability of the gauche versus trans TFE have been reported. − It was only in the trimer of TFE where trans -TFE was detected experimentally, making a possible link to the bulk phase properties where trans -TFE was reported to exist with an abundance of 40% .…”

Section: Introductionmentioning

confidence: 99%

Alternating 1-Phenyl-2,2,2-Trifluoroethanol Conformational Landscape With the Addition of One Water: Conformations and Large Amplitude Motions

et al. 2022

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The 1:1 adduct of 1-phenyl-2,2,2-trifluoroethanol (PhTFE), a chiral fluoroalcohol, with water was investigated using chirped pulse Fourier transform microwave spectroscopy and computational methods. While PhTFE itself was predicted to have three minima, I (gauche+), II (trans), and III (gauche−), only I and II were stable and only I was observed experimentally. A systematic search of the PhTFE···H2O conformational landscape identified 110 stable minima, 14 of which are within a 15 kJ mol–1 energy window. Rotational spectra of the two PhTFE···H2O conformers along with several deuterium and 18O isotopologues were assigned, and the isotopic data were used to verify the corresponding structures. In the two observed monohydrate conformers, one contains PhTFE I where the water subunit is inserted into the existing intramolecular OH···F contact of I, and the binary adduct is stabilized by two intermolecular contacts: OH···OW and HW···F, whereas the other contains PhTFE II where the water subunit interacts with both the alcohol hydrogen and phenyl ring of II, demonstrating that interaction with water sufficiently stabilizes II for its observation in a jet expansion. Interestingly, the predicted electric dipole moment components at the identified minima deviate considerably from the experimental ones. Such deviations were analyzed in terms of dynamic effects associated with the large amplitude motions of the unbound HW. In addition, tunnelling effects associated with the exchange of the bonded and nonbonded HW were also discussed.

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Section: Introductionmentioning

confidence: 99%

Alternating 1-Phenyl-2,2,2-Trifluoroethanol Conformational Landscape With the Addition of One Water: Conformations and Large Amplitude Motions

et al. 2022

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“…It is clear from Table S4 that fitting 𝐷 is essential to obtain not only better standard deviations for the parent species and the 34 S isotopologue fits but also a better accuracy of the rotational constants. However, the accuracy of the rotational constants for all 13 C isotopologue fits is lower than for the parent species and the 34 S isotopologue fits if 𝐷 is fitted, probably due to the smaller data sets. Therefore, 𝐷 was fixed to the value of the parent species fit in all 13 C isotopologue fits.…”

Section: Microwave Spectroscopymentioning

confidence: 95%

“…However, the accuracy of the rotational constants for all 13 C isotopologue fits is lower than for the parent species and the 34 S isotopologue fits if 𝐷 is fitted, probably due to the smaller data sets. Therefore, 𝐷 was fixed to the value of the parent species fit in all 13 C isotopologue fits.…”

Section: Microwave Spectroscopymentioning

confidence: 95%

“…To accurately determine the molecular structure and methyl internal rotation parameters of 2MTP, in the present study, we applied a state-of-the-art molecular jet Fourier-transform microwave (MJ-FTMW) spectroscopy technique combined with modern quantum chemical calculations. This theory-experiment joint-venture has become the method of choice to investigate many small molecular systems similar to 2MTP [11][12][13][14][15]. The high sensitivity and resolution of the experimental setup also enabled the observation of the 34 S and 13 C isotopologues in natural abundance, allowing the determination of the structure of 2MTP in the gas phase for the heavy atom backbone.…”

Section: Introductionmentioning

confidence: 99%

“…This theory-experiment joint-venture has become the method of choice to investigate many small molecular systems similar to 2MTP [11][12][13][14][15]. The high sensitivity and resolution of the experimental setup also enabled the observation of the 34 S and 13 C isotopologues in natural abundance, allowing the determination of the structure of 2MTP in the gas phase for the heavy atom backbone.…”

Section: Introductionmentioning

confidence: 99%

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Barrier to Methyl Internal Rotation and Equilibrium Structure of 2-Methylthiophene Determined by Microwave Spectroscopy

Koziol

Hadki

Lüchow

et al. 2023

Spectroscopy Journal

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The microwave spectrum of 2-methylthiophene was recorded in a frequency range from 2 to 26.5 GHz using a molecular-jet Fourier transform microwave spectrometer with a Fabry–Pérot type resonator chamber and coaxial arrangement of the resonator and the molecular beam. Measuring and assigning spectra of the 34S and 13C isotopologues allowed the determination of the semiexperimental equilibrium structure (reSE). Comparing the structure to that of thiophene revealed a decrease in the ∠(S−C2−C3) angle from 111.595(6)° to 111.37(1)° by addition of the methyl group to the C(2) position, as well as an increase in the S−C2 bond length from 1.7102(1) Å to 1.7219(2) Å. A–E splittings from internal rotation of the methyl group were observed, and the V3 potential in the vibrational ground state was determined to be 197.7324(18) cm−1. The V3 value and the rotational constants A, B, C were calculated with a large number of different methods and basis sets for benchmarking purposes by comparing them to the fitted parameters. The V3 value was also compared to those of other thiophene and furan derivatives to gain a better understanding of the steric and electrostatic effects in these classes of compounds.

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GaMD simulations as an alternative in the TFE-water mixture description

Pérez-Trejo,

Dominguez

2023

J Mol Model

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Context: 2,2,2-Trifluoroethanol has been widely used to study the structure and dynamic properties of intrinsically disordered proteins. Experimentally, it is known that TFE-water mixtures stabilize secondary structures of IDPs, and therefore, it allows the studying of conformational ensembles of these proteins. In the last decades, molecular dynamic simulations have helped study the IDPs’ conformational ensemble. Unfortunately, conventional MD requires very long simulation times to describe the properties of IDPs. Therefore, a variety of accelerated sampling techniques have been developed and employed. The TFE-water mixture arrangement description through MD has faced substantial difficulties since emulating the TFE nanocrowding at certain TFE:H$$_2$$ 2 O ratios (around 15–40% of TFE). In this work, we determine the most suitable conditions that reproduce experimentally reported properties of TFE-water mixtures. We compared the employment of conventional MD and GaMD simulations and various water parameters. Our results show that the combination of parameters that better reproduce the experimental information is the combination of the TIP4PD water model and GaMD simulations. Therefore, these conditions help accurately describe the structural ensemble of IDPs in TFE-water mixtures. Methods: Conventional MD and GaMD simulations were performed under AMBER 18 software. The TFE and water molecules were described using GAFF2 and a variety of water models, such as TIP3P, TIP4P2005, TIP4PD, and TIP5P, respectively. The systems were simulated a 100 ns at 298 K. Graphical abstract

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Rotation-tunneling spectra and barriers of isotopologues of 2,2,2-trifluoroethanol and 2,2,3,3,3-pentafluoropropanol

Cited by 3 publications

References 35 publications

Alternating 1-Phenyl-2,2,2-Trifluoroethanol Conformational Landscape With the Addition of One Water: Conformations and Large Amplitude Motions

Alternating 1-Phenyl-2,2,2-Trifluoroethanol Conformational Landscape With the Addition of One Water: Conformations and Large Amplitude Motions

Barrier to Methyl Internal Rotation and Equilibrium Structure of 2-Methylthiophene Determined by Microwave Spectroscopy

GaMD simulations as an alternative in the TFE-water mixture description

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