Unusual dynamic behavior in the isotropic phase of banana mesogens detected by 2H NMR line width and T2 measurements

Valentina Domenici; Marco Geppi; Carlo Alberto Veracini; Robert Blinc; Andrija Lebar; Bostjan Zalar

doi:10.1021/jp046278l

Unusual dynamic behavior in the isotropic phase of banana mesogens detected by 2H NMR line width and T2 measurements

J Phys Chem B. 2005 Jan 20;109(2):769-74. doi: 10.1021/jp046278l.

Authors

Valentina Domenici¹, Marco Geppi, Carlo Alberto Veracini, Robert Blinc, Andrija Lebar, Bostjan Zalar

Affiliation

¹ Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy.

PMID: 16866440
DOI: 10.1021/jp046278l

Abstract

In this work the first experimental observation of a peculiar behavior in the isotropic phase of liquid crystals by means of 2H NMR is reported. In particular, two five-ring banana-shaped mesogens, the 1,3-phenylenebis{4,4'-(11-undecenyloxy)benzoyloxy}benzoate (Pbis11BB) and its 4-chloro homologue (ClPbis11BB), selectively deuterium labeled on their central rings, are the subject of our investigation. The dynamic behavior of the two liquid crystals was studied in their isotropic phases and in the nematic phase of ClPbis11BB by means of 2H NMR line width and spin-spin relaxation time (T2) analysis. The results obtained reveal that the unusual line broadening observed in the 2H NMR spectra in the isotropic phase, even far above the isotropic phase-mesophase transition, has a homogeneous nature, thus indicating the presence of reorientational motions much slower than in conventional isotropic liquid-crystalline phases.