Naslov
Polarized Vibrational Spectra of p-Substituted Nitro and Dinitro cis- and trans-Stilbenes

Autori
Miljanić, Snežana ; Meić, Zlatko ; Keresztury, Gabor

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
EUCMOS 2008 Book of Abstracts / Musić, Svetozar ; Ristić, Mira ; Krehula, Stjepan - Zagreb, 2008

ISBN
978-953-6690-76-3

Skup
XXIX European Congress on Molecular Spectroscopy

Mjesto i datum
Opatija, Hrvatska, 31.08.2008. - 05.09.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
polarized spectrum; stilbene; vibrational spectroscopy

Sažetak
Polarized IR spectra of p-nitro and p, p’ -dinitro derivatives of stilbene were measured in anisotropic (nematic liquid crystalline) solvent. Using the Thulstrup-Eggers stepwise reduction procedure, based on the interactive subtraction of the two polarized IR spectra A(parallel) and A(perpendicular), orientational parameters of nearly planar, low symmetry stilbene molecules were determined. Dichroic ratios (subtraction factors), Ru (u = x, y, z), of observed vibrational transitions were evaluated and orientational parameters along the out-of-plane axis, Kx, the short in-plane axis, Ky, and the long in-plane axis, Kz, were calculated. Since the rotation around the double bond changes the molecular geometry, different set of orientation parameters were determined for each molecule. The Kz values indicate, as expected, that the trans-isomers are better oriented along the long in-plane axis than the cis-isomers. In addition, the Kz value for the mono substituted trans-stilbene, which is higher than the one for the disubstituted trans-stilbene, implies a possible involvement of the nitro groups in dipole-dipole interactions responsible for orientational mechanism of solute molecules in nematic solvent. Finally, polarized Raman spectra of crystalline stilbene substances were measured and depolarization ratios of selected vibration modes calculated. The values will be compared with those of the parent trans-stilbene molecule.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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