The FT microwave spectrum of benzo[b]thiophene: first application of a new heatable beam nozzle

Welzel, Alexandra; Stahl, Wolfgang

doi:10.1039/a906591a

Cited by 10 publications

(3 citation statements)

References 7 publications

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“…For that reason, complete series of molecules of biological interest, such as building blocks, have escaped microwave spectroscopy studies. Several laboratories have incorporated heatable nozzles [40][41][42] into their microwave spectrometers to overcome the problem, but, in many cases, thermal instability constituted an important drawback. The pioneering works of Brown [43] or Suenram [44] and co-workers on molecular building blocks were carried out using such heating methods.…”

Section: -Ch(r)-coomentioning

confidence: 99%

Microwave Spectroscopy of Biomolecular Building Blocks

Alonso

López

2014

Topics in Current Chemistry

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Microwave spectroscopy, considered as the most definitive gas phase structural probe, is able to distinguish between different conformational structures of a molecule, because they have unique spectroscopic constants and give rise to distinct individual rotational spectra.Previously, application of this technique was limited to molecular specimens possessing appreciable vapor pressures, thus discarding the possibility of studying many other molecules of biological importance, in particular those with high melting points, which had a tendency to undergo thermal reactions, and ultimately degradation, upon heating.Nowadays, the combination of laser ablation with Fourier transform microwave spectroscopy techniques, in supersonic jets, has enabled the gas-phase study of such systems. In this chapter, these techniques, including broadband spectroscopy, as well as results of their application into the study of the conformational panorama and structure of biomolecular building blocks, such as amino acids, nucleic bases, and monosaccharides, are briefly discussed, and with them, the tools for conformational assignation - rotational constants, nuclear quadrupole coupling interaction, and dipole moment.

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Section: -Ch(r)-coomentioning

confidence: 99%

Microwave Spectroscopy of Biomolecular Building Blocks

Alonso

López

2014

Topics in Current Chemistry

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“…The rotational spectra of several two-ring molecules made of condensed six-and five-membered aromatic rings, among which indene can be considered the prototype, have been investigated. [1][2][3][4][5][6][7][8][9][10] These molecules are of interest in biochemistry because some biological bases (for example purine 8 ) have such a shape. They often exist as tautomers and rotationally resolved spectroscopy is especially useful to find their relative energies 5,11,12 or, at least, to establish which is the most stable species.…”

Section: Introductionmentioning

confidence: 99%

Structure, dipole moment and large amplitude motions of 1-benzofuran

Maris

Giuliano

Melandri

et al. 2005

Phys. Chem. Chem. Phys.

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The rotational spectrum of 1-benzofuran has been investigated by three different rotational spectroscopy techniques: (i) millimeterwave absorption free jet spectroscopy, useful for a fast assignment of the spectrum; (ii) molecular beam Fourier transform microwave spectroscopy, sensitive to detect less abundant isotopic species in natural abundance; (iii) waveguide conventional microwave spectroscopy, useful for the study of intramolecular dynamics, through the rotational spectra of the vibrational satellites of low energy modes. Besides the rotational spectrum of the ground state of the normal species, the spectra of 9 singly substituted 13C and 18O isotopomers in natural abundance, and of 6 vibrational satellites, have been measured. Precise structural parameters for the molecule, as well as information on the potential energy surface of the low energy vibrations, have been obtained. The dipole moment components have been determined to be micro(a)= 0.216 (2) and micro(b)= 0.720 (3) D, respectively.

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“…BTA was purchased from Lancaster at a purity of 97% and was used as received. The sample was placed into a heated reservoir [41] at a temperature of 150 • C under helium gas stream. The total helium pressure was set to 2 bar.…”

Section: Microwave Spectroscopymentioning

confidence: 99%

The Microwave Rotational Electric Resonance (RER) Spectrum of Benzothiazole

et al. 2023

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The microwave spectra of benzothiazole were measured in the frequency range 2–26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. Hyperfine splittings arising from the quadrupole coupling of the 14N nucleus were fully resolved and analyzed simultaneously with the rotational frequencies. In total, 194 and 92 hyperfine components of the main species and the 34S isotopologue, respectively, were measured and fitted to measurement accuracy using a semi-rigid rotor model supplemented by a Hamiltonian accounting for the 14N nuclear quadrupole coupling effect. Highly accurate rotational constants, centrifugal distortion constants, and 14N nuclear quadrupole coupling constants were deduced. A large number of method and basis set combinations were used to optimize the molecular geometry of benzothiazole, and the calculated rotational constants were compared with the experimentally determined constants in the course of a benchmarking effort. The similar value of the χcc quadrupole coupling constant when compared to other thiazole derivatives indicates only very small changes of the electronic environment at the nitrogen nucleus in these compounds. The small negative inertial defect of −0.056 uÅ2 hints that low-frequency out-of-plane vibrations are present in benzothiazole, similar to the observation for some other planar aromatic molecules.

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The FT microwave spectrum of benzo[b]thiophene: first application of a new heatable beam nozzle

Cited by 10 publications

References 7 publications

Microwave Spectroscopy of Biomolecular Building Blocks

Microwave Spectroscopy of Biomolecular Building Blocks

Structure, dipole moment and large amplitude motions of 1-benzofuran

The Microwave Rotational Electric Resonance (RER) Spectrum of Benzothiazole

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