AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For ...AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For all optimized configurations,there is no imaginary frequency in vibrational analysis.The stable configuration,electronic structure,and some molecular properties of title compounds(heat of formation,dipole moment and energy level of frontal molecule orbital,etc) are frist reported.The calculated results are fully discussed with rspect to the organic structure theory.展开更多
A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three di...A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three dimentional, tree-like, starburst structure.Its phase behavior was K64 Sx115 SA123N138I. Compared with its AZO-meso-unit, 4-nitro-4’- (llydroxyhexyl)-azobenzene, whose phase behavior was K122N132I, its phase range was enlarged about 64 ℃ and two more liquid crystalline phases SA Sx were found.展开更多
Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD....Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 ℃ and on the cooling course from 183 to 64 ℃. After cooling, the smectic E(S E) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(S A) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S A187I182S A57S E47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K·mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.展开更多
文摘AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For all optimized configurations,there is no imaginary frequency in vibrational analysis.The stable configuration,electronic structure,and some molecular properties of title compounds(heat of formation,dipole moment and energy level of frontal molecule orbital,etc) are frist reported.The calculated results are fully discussed with rspect to the organic structure theory.
文摘A liquid crystalline carbosilane dendrimer has been synthesized in successive steps, resulting in the formation of defined, unimolecular compound. 12 AZO-meso-units were attached on its periphery and it has a three dimentional, tree-like, starburst structure.Its phase behavior was K64 Sx115 SA123N138I. Compared with its AZO-meso-unit, 4-nitro-4’- (llydroxyhexyl)-azobenzene, whose phase behavior was K122N132I, its phase range was enlarged about 64 ℃ and two more liquid crystalline phases SA Sx were found.
文摘Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 ℃ and on the cooling course from 183 to 64 ℃. After cooling, the smectic E(S E) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(S A) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S A187I182S A57S E47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K·mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.
