New SmCG Phases in a Hydrogen-Bonded Bent-Core Liquid Crystal Featuring a Branched Siloxane Terminal Group was written by Chen, Wei-Hong;Chuang, Wei-Tsung;Jeng, U-Ser;Sheu, Hwo-Shuenn;Lin, Hong-Cheu. And the article was included in Journal of the American Chemical Society in 2011.Recommanded Product: 35065-86-2 This article mentions the following:
The authors synthesized three analogous bent-core mols., a H-bonded complex and a covalent-bonded compound with branched siloxane units (H-SiO and C-SiO, resp.) and a H-bonded complex with an alkyl unit (H-Alk), and studied the effects of the H bonding and branched siloxane terminal units on their mesomorphic properties. The covalent-bonded compound C-SiO and the H-bonded complex H-Alk exhibited typical SmCP phases; in contrast, the H-bonded complex H-SiO exhibited general tilt smectic (SmCG) phases with highly ordered layer structures (i.e., SmCG̃2PF-USmCG2PA-SmCG2PF-SmCGPF upon cooling). During the SmCG-type phase transition process, a 2-dimensional-modulated ribbon structure transferred into highly ordered layers via undulated layers, as the H-bonding strength increased with reduced temperatures As the SmCG domains were aligned under d.c. elec. fields, a gradual decrease in the leaning angle from ∼60° to 50° (while the tilt angle kept at ∼31°) could be determined by in situ wide-angle x-ray scattering (WAXS). Combined with FTIR and Raman spectroscopic data, the authors’ results suggest that the change in the leaning angle was governed by the competition of the H bonds and microsegregation of siloxane units within the bilayer structure of the H-bonded complex H-SiO. The ferroelec.-(antiferroelec.)-ferroelec. transitions proven by the switching current responses in the SmCG-type phases of H-SiO reveal that the polar switching occurred through collective rotations around the long axis of H-SiO. Therefore, novel SmCG phases with highly ordered 2-dimensional-structures were induced by the effects of the H bonding and branched terminal siloxane unit in the bent-core H-bonded LC complex H-SiO. In the experiment, the researchers used many compounds, for example, 3-Bromophenyl acetate (cas: 35065-86-2Recommanded Product: 35065-86-2).
3-Bromophenyl acetate (cas: 35065-86-2) belongs to organobromine compounds. Many of the organo bromine compounds are relatively nonpolar. Bromine is more electronegative than carbon (2.8 vs 2.5) and hence the carbon in a carbonbromine bond is electrophilic in nature. In the pharmaceutical industry organo bromine derivatives are used as sedatives, vasodilators, antiseptic agents, and anticancer agents.Recommanded Product: 35065-86-2
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary