In the present work, the quite intriguing question of the temperature dependence of the inter-ring angle of biphenyl in fluid condensed phases has been investigated by the proton liquid crystal nuclear magnetic resonance technique. The spectra of the molecule dissolved in three different thermotropic uniaxial solvents (one of which shows also a smectic A phase) at different values of temperature have been analysed by standard procedures, and the resulting temperature- dependent dipolar coupling sets have been rationalised by the additive potential for the treatment of the ordering interactions method, combined with the direct probability description of the torsional curve, in order to obtain the distribution of the twist angle j for each temperature. The results emphasise a very slight but unequivocal and systematic increase of jM (the most probable value of the dihedral angle) with temperature, so qualitatively confirming what was previously found by a cruder hybrid approach (based on experimental quadrupolar splittings of perdeuteriated biphenyl combined with computer-simulated order parameters) carried out by two of the present authors (Celebre, G.; De Luca, G.;Mazzone, G. J. Mol. Struct. (THEOCHEM) 2005, 728, 209–214).

Exploiting the information content of dipolar couplings: determination of the temperature dependence of the inter-ring twist angle of biphenyl dissolved in uniaxial mesophases

CELEBRE, Giorgio;DE LUCA, Giuseppina;
2010

Abstract

In the present work, the quite intriguing question of the temperature dependence of the inter-ring angle of biphenyl in fluid condensed phases has been investigated by the proton liquid crystal nuclear magnetic resonance technique. The spectra of the molecule dissolved in three different thermotropic uniaxial solvents (one of which shows also a smectic A phase) at different values of temperature have been analysed by standard procedures, and the resulting temperature- dependent dipolar coupling sets have been rationalised by the additive potential for the treatment of the ordering interactions method, combined with the direct probability description of the torsional curve, in order to obtain the distribution of the twist angle j for each temperature. The results emphasise a very slight but unequivocal and systematic increase of jM (the most probable value of the dihedral angle) with temperature, so qualitatively confirming what was previously found by a cruder hybrid approach (based on experimental quadrupolar splittings of perdeuteriated biphenyl combined with computer-simulated order parameters) carried out by two of the present authors (Celebre, G.; De Luca, G.;Mazzone, G. J. Mol. Struct. (THEOCHEM) 2005, 728, 209–214).
LXNMR; Dipolar Couplings; Molecular Conformations
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11770/144730
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 21
  • ???jsp.display-item.citation.isi??? 20
social impact