Nematic calamities

Calamities are the most common nematics, wherein molecules can be approximated as rods, which preferentially align their long axis in the same direction. 

Monosubstitution, as in the case of conventional calamities, is expected to lead to a predominance of nematic and smectic A phases, with possibly nematic phases being favored because of the repulsive steric effects of the ferrocene unit causing a reduced ability of the molecules to pack in layers. Disubstitution, on the other hand, may be expected to lead to smectic polymorphism because the overall shape of the molecule can be extended and varied from being linear to being slightly bent. For instance, let us first consider disubstitution in one of the ferrocene rings. In... 

Table A.4. Flexoelectric coefficients of nematic liquid crystals using naming convention in Eq. (A.l) other calamities. 

The nematic phase of nonlinear mesogens may be biaxial - a translationally disordered fluid phase with two directors n and o specifying the orientational order (Fig. 5.3). Biaxial order in a nematic is predicted to occur [29] if the shape anisotropy of the idealized molecule (discoid) representing the nonlinear meso-gen is appropriately intermediate between the prolate shape of calamities and the oblate shape of discotics. Discoid-shaped mesogens lend themselves to a variety of stratified phases. Ferroelectric (Sapp) and antiferroelectric (Sapa) layer motifs in the normal smectic phases of discoid-shaped mesogens are readily envisioned (Fig. 5.4), but less obvious is the possibility of generating chiral supramolecular structures from such achiral discoid-shaped mesogens (Fig. 5.5) [30]. 

E phases, calamities 12 edge disclinations, chiral nematics 354 Ehrlich magic bullet, chromonics 984 elastic constants 63, 79 ff... 

---