On the Importance of the Molecular Core Interactions on the Induction of the High Optical Tilt Angle

Abstract

Two smectogens being structural analogs with the opposite space orientation of the COO ester group in the molecular core exhibit extremely different tilt angles. A molecular mechanism of the induction of the high optical tilt angle is searched on the basis of extensive investigations of those compounds.

Computer modeling of molecules and investigations of physical parameters of smectic phases were done. Different molecular aggregates forming smectic phases were observed. The size and shape of those aggregates are estimated on the basis of measurements and calculations. The different values of the tilt angles in studied compounds were discussed.

Keywords:

• de Vries SmA*
• phase
• dimmerisation
• orthoconic smectic phases
• smectic liquid crystals
• tilt angle

Notes

μ – the magnitude of the molecular dipole moment ,

μ_x, μ_y, μ_z-the x, y, z components of the molecular dipole moment ,

μ_⊥ – the perpendicular component of the dipole moment

ϕ – the angle between the dipole moment and short Oz molecular axis,

γ – the angle between the dipole moment and long Ox molecular axis,

β – the angle between rigid molecular core and the chiral part.

Spacing d¹ and d², the tilt angle θ^E are taken out of the experiment.

The dimmer length of L₂₀ in SmA* was estimated as .

The dimmer length of L₂₀ in SmC* was estimated as .

The dimmer length of L₂₀ in SmH* was estimated as .

The angle of θ^T in tilted SmH* phase of CO-20 was estimated as θ^T = .

The spacing of was estimated as .

The spacing of was estimated as .