Investigation into the Mechanism for Generation of the Helical Axis in Cholesteric Lyotropic Liquid Crystals

Article abstract of DOI:10.1021/j100188a058

The molecular based process responsible for the generation of the helical axis in the cholesteric mesophase of potassium N-dodecanoyl-L-alaninate, decanol, electrolyte, and water has been investigated.The headgroup dipolar couplings have been correlated with deuterium quadrupole splittings from the aliphatic chain as a function of amphiphile concentration.The results show that the change in the pitch of the helical axis with concentration is reflected by a change in preferred conformation of the amphiphile.This change in conformation is centered about the amide bonds where the aliphatic chain is joined to the alaninate headgroups.The effect presumably results from destabilization of the normally preferred rotamer in favor to others and will have its source in selective interactions between the chiral centers of adjacent amphiphiles.Studies similar to those discussed show that the variation in pitch caused by temperature changes is not correlated with similar selective changes in headgroup orientation.