English abstract
This study aimed at synthesizing and studying the mesomorphic properties and the
thermal behavior of four novel calamitic fluorinated chiral organosiloxane liquid
crystals using established protocols and procedures. The four mesogenic materials
(7a, 7b, 7c& 7d), contain a chiral side chain with 7 carbons, while the other side
chain is made up of long chain hydrocarbon terminated by an organosiloxane. The
lengths of the carbon chain tail are (C-7, C-8, C-10, and C-11) respectively. The
general name of the synthesized LCs is (R)-heptan-2-yl 4'-((2-fluoro-4-((n-
(1,1,1,3,5,5,5-heptamethyltrisiloxan-3yl)alkenyl)oxy)benzoyl)oxy)-3'-nitro [1,1'biphe
-nyl]-4-carboxylate, where n= 7, 8, 10 &11 for 7a, 7b, 7c & 7d, respectively. The
yield of the four synthesized LCs was: 30.2%, 54.2%, 13.4%, and 40.7% for 7a, 7b,
7c & 7d, respectively.
The structures of all synthesized final products and intermediates were characterized
using 1
H-NMR, and 13C-NMR spectroscopy. However, phase transition behavior was
studied using polarized optical microscopy (POM). The four mesogenic materials C 7 (7a), C-8 (7b), C-10 (7c) and C-11 (7d) do exhibit biphasic SmA* and SmC*
phases upon cooling (and heating). Moreover, this study confirms that all the liquid
crystals (7a, 7b, 7c& 7d) show ferroelectric response, and so they are ferroelectric
LC (FLC).
