Low frequency internal modes of 1,2,4,5-tetramethylbenzene, tetramethylpyrazine and tetramethyl-1,4-benzoquinone

Pawlukojć, A.; Natkaniec, I.; Bator, G.; Sobczyk, L.; Grech, E.; Nowicka‐Scheibe, J.

doi:10.1016/j.saa.2005.06.030

Cited by 25 publications

(15 citation statements)

References 13 publications

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“…In the case of infra-red and Raman spectra the selection rules apply and moreover the intensities of respective bands can be very low. In contrast, such modes in INS spectra are characterized by the high intensities [29][30][31].…”

Section: Introductionmentioning

confidence: 93%

INS, DFT and temperature dependent IR investigations of dynamical properties of low temperature phase of choline chloride

Pawlukojć

Hetmańczyk

2014

Chemical Physics

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Section: Introductionmentioning

confidence: 93%

INS, DFT and temperature dependent IR investigations of dynamical properties of low temperature phase of choline chloride

Pawlukojć

Hetmańczyk

2014

Chemical Physics

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“…The IINS technique is a powerful method for analyzing modes with participation of H-atoms due to the large neutron scattering cross-section of hydrogens as well as of carbon atoms. 36 The most intense band at 258 cm 1 in the IINS spectrum measured at 20 K is supposed to originate from the torsion of the methyl substituent (Table 2) in which there is the largest concentration of hydrogen atoms in the MNA molecule. This band is neither observed in the IR spectrum of MNA suspension in nujol nor in the Raman spectrum of powdered MNA (Figs 6 and 7, respectively).…”

Section: Lattice and Low Wavenumber Vibrationsmentioning

confidence: 99%

Spectroscopic, structural and theoretical studies of 2‐methyl‐4‐nitroaniline (MNA) crystal. Electronic transitions in IR

Okwieka

Szóstak

Misiaszek

et al. 2008

J Raman Spectroscopy

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Polarized FT-IR, Raman, neutron scattering (IINS), and UV-Vis-NIR spectra of 2-methyl-4-nitroaniline (MNA) crystal plates, powder, and solutions were measured in the 10-50 000 cm −1 range. The FT-IR spectrum of deuterated MNA (DMNA) in KBr pellet, the Raman spectrum of the DMNA powder as well as the EPR spectrum of the MNA powder were also recorded. Complete assignments of bands to normal vibrations have been proposed. Density functional theory (DFT) calculations of wavenumbers and potential energy distribution (PED) have been performed to strengthen the assignments. The analysis of vibrational and electronic spectra has revealed vibronic couplings in MNA molecules in solutions and in crystals. In the polarized FT-IR spectra of the crystal five unusually large bands are observed in MIR and NIR regions. Their origin is discussed in terms of N-H· · ·O, C-H· · ·O, C-H· · ·H-N hydrogen bonds, intermolecular charge transfers, electrostatic interactions, and ion radicals formation in the crystal. The role of a methyl group introduction to 4-nitroaniline is analyzed. The crystal structure of MNA at the room temperature was re-investigated.

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“…The surrounding of the CH 3 groups is more important, as was shown in several papers. [12][13][14][15][16][17] This effect causes a change in the rotational potential. However, we also have to take into account another source affecting the dynamics of the CH 3 groups, namely, the charge distribution in the pyridyl rings.…”

Section: Introductionmentioning

confidence: 99%

4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls: The structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid

Bator

Sawka‐Dobrowolska

Sobczyk

et al. 2011

The Journal of Chemical Physics

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The crystal and molecular structures of 4,4(')- and 6,6(')-dimethyl-2,2(')-bipyridyl complexes with 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (chloranilic acid, CLA) have been determined and compared with those of the complex with the 5,5(')-derivative, which is known to possess interesting antiferroelectric properties. In the crystalline state, all three compounds form hydrogen bonded chains with N(+)-H···O(-) and O-H···N bridges on both sides of the bipyridyl constituent. The comparison of three derivatives indicates that the N(+)-H···O(-) hydrogen bonds are shortest for the 5,5(')-dimethyl complex. The 4,4(')- and 6,6(')-derivatives do not show any ferroelectric feature. The 6,6(')-one is, however, characterized by a continuous phase transition, revealed in the differential scanning calorimetry, dilatometric, and dielectric characteristics. The tunneling splitting measured by neutron backscattering in the energy range ±30 μeV for the neat dimethyl bipyridyls and their complexes with CLA indicates that the different splittings are primarily due to the crystal packing effect and that charge transfer between interacting compounds plays only a minor role.

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Low frequency internal modes of 1,2,4,5-tetramethylbenzene, tetramethylpyrazine and tetramethyl-1,4-benzoquinone

Cited by 25 publications

References 13 publications

INS, DFT and temperature dependent IR investigations of dynamical properties of low temperature phase of choline chloride

INS, DFT and temperature dependent IR investigations of dynamical properties of low temperature phase of choline chloride

Spectroscopic, structural and theoretical studies of 2‐methyl‐4‐nitroaniline (MNA) crystal. Electronic transitions in IR

4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls: The structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid

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