The detection of chiral perturbations in ferroelectric liquid crystals induced by dopants with axially chiral 2,2′-spirobiindan-1,1′-dione cores

Abstract

Chiral perturbations exerted by the dopants 6,6′-diheptyloxy-2,2′-spirobiindan-1,1′-dione (2) and 6,6′-diheptoyloxy-2,2′-spirobiindan-1,1′-dione (4) in the SmC phase of the liquid crystal host 4-(4′-heptyl[1,1′-biphen]-4-yl)-1-hexylcyclohexanecarbonitrile (NCB76) are investigated via (i) probe experiments using the structural analogue 5,5′-diheptyloxy-2,2′-spirobiindan-1,1′-dione (1) as chiral probe, and (ii) ²H NMR experiments using deuterated forms of 2 and NCB76. The results suggest that a probe experiment is more effective than ²H NMR in detecting chiral perturbations provided that the structure of the probe is similar to that of the chiral dopant, and that the chiral perturbations exerted by the dopant may be modeled as a ‘chiral field’ which is conceptually similar to the electric field exerted by a point charge that decays with increasing distance from the latter.