The (1) H NMR spectrum of pyrazole in a nematic phase

Patricio Provasi; María Luisa Jimeno; Ibon Alkorta; Felipe Reviriego; José Elguero; Jukka Jokisaari

doi:10.1002/mrc.4422

The (1) H NMR spectrum of pyrazole in a nematic phase

Magn Reson Chem. 2016 Aug;54(8):637-40. doi: 10.1002/mrc.4422. Epub 2016 Mar 6.

Authors

Patricio Provasi¹, María Luisa Jimeno², Ibon Alkorta³, Felipe Reviriego³, José Elguero³, Jukka Jokisaari⁴

Affiliations

¹ Physics Department, University of Northeast, Av. Libertad 5500, W 3404 AAS, Corrientes, Argentina.
² CENQUIOR (CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain.
³ Instituto de Química Médica (CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain.
⁴ NMR Research Group, University of Oulu, 90014, Oulu, Finland.

PMID: 26947581
DOI: 10.1002/mrc.4422

Abstract

The experimental (1) H nuclear magnetic resonance (NMR) spectrum of 1H-pyrazole was recorded in thermotropic nematic liquid crystal N-(p-ethoxybenzylidene)-p-butylaniline (EBBA) within the temperature range of 299-308 K. Two of three observable dipolar DHH -couplings appeared to be equal at each temperature because of fast prototropic tautomerism. Analysis of the Saupe orientational order parameters using fixed geometry determined by computations and experimental dipolar couplings results in a situation in which the molecular orientation relative to the magnetic field (and the liquid crystal director) can be described exceptionally by a single parameter. Copyright © 2016 John Wiley & Sons, Ltd.

Keywords: 1H-pyrazole; D couplings; DFT calculations; orientational order; tautomerism.