New steroid α,β-unsaturated ketones as chiral components of induced cholesteric liquid crystal systems

Influence of the rigidity of the steroid core in the structure of chiral dopants on the temperature dependence of cholesteric short pitch

“…in some measure have similar peculiarities of the molecular structure to (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one and their acetates described by us earlier[36,37].Acetates of (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one exhibited HTP values from 45 to 61 µm -1 mol.fr.-1 in nematics E63 and LC-1289, which are close to those obtained for estrone derivatives 8a-i. The LC systems comprising acetates of (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one also showed relatively weak temperature dependence of max[37].…”

“…The molecular structures of both series of dopants are characterized by inflexible highly chiral steroid cores. The cinnamoyl group in molecules of both series of steroids has the Е-configuration confirmed by the results of nuclear Overhauser effect experiment as well as semiempirical AM1 calculations[36][37][38]. Only the presence of terminal 3-acetoxy or 3-hydroxy substituents and rotation around C(20)-Ar bond in the arylidene fragment (the torsion angle φ Ar ) impart some flexibility to the molecular structure of the dopants.The detailed AM1 calculations for (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one and their acetates revealed a set of rotamers at the arylidene group[36].…”

“…The LC systems comprising acetates of (E)-16-arylidene derivatives of 3β-hydroxyandrost-5-en-17-one also showed relatively weak temperature dependence of max[37]. The molecular structures of both series of dopants are characterized by inflexible highly chiral steroid cores.…”