Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

PDF

2006

Achiral Molecules

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

Odd-Even Effects In Bent-Core Compounds Containing Terminal N-Alkyl Carboxylate Groups, S. Umadevi, Antal Jakli, B. Sadashiva Oct 2006

Odd-Even Effects In Bent-Core Compounds Containing Terminal N-Alkyl Carboxylate Groups, S. Umadevi, Antal Jakli, B. Sadashiva

Antal Jakli

A homologous series of eleven five-ring symmetrical bent-core compounds containing terminal n-alkyl carboxylate groups were synthesized, characterized and their dielectric and electro-optical properties have been investigated. The lower homologues (n = 6-11) of the series show B-2 structures with an interesting odd-even effect concerning their local director tilt and polar arrangements. This odd-even effect probably is due to steric (entropic) reasons, which are not suppressed by the relatively low polar interaction. Three of the middle homologues display a B-7' phase, which is bistable and shows linear electro-optical switching with a transition to the chiral antiferroelectric smectic phase at a lower …


Bistable Linear Electro-Optical Switching In The B-7 ' Phase Of Novel Bent-Core, S. Umadevi, Antal Jakli, B. K. Sadashiva May 2006

Bistable Linear Electro-Optical Switching In The B-7 ' Phase Of Novel Bent-Core, S. Umadevi, Antal Jakli, B. K. Sadashiva

Antal Jakli

Three novel symmetrical bent-core compounds were synthesized where the terminal alkoxy linkages of the original bent-core inesogen forming a B-2 phase was converted to n-alkyl carboxylates. It is found that instead of the B-2 phase, all three compounds exhibit a transition between B-7' and B-2 mesophases. The physical and electro-optical properties have been investigated by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and electric field experiments. The higher temperature B-7' phase has been shown to exhibit bistable but analogous linear electro-optical Switching Without,my observable polarization peak. We analyze two theoretical models and find that a local triclinic symmetry may …