1429894-53-0Relevant articles and documents
Azo monomers exhibiting low layer shrinkage at the SmA-SmC transition and trans-cis light-induced isomerization
Garcia, Tonatiuh,Larios-Lopez, Leticia,Rodriguez-Gonzalez, Rosa Julia,Torres-Lubian, Jose Roman,Navarro-Rodriguez, Damaso
, p. 3937 - 3944 (2012)
Methacrylic monomers containing a (phenylene)azobenzene unit substituted with a lateral cyano group and alkyl chains of different length are synthesized and characterized by NMR techniques. Their liquid-crystalline properties are studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. All monomers exhibit a mesomorphic behavior that extends over wide temperature ranges with nematic and orthogonal or tilted smectic-type mesophases, depending on the length of the terminal chain. The smectic structures are determined to be single-layered with a low layer shrinkage (a high smectic order promoted by both π-π and bond dipole-bond dipole interactions between cyano-substituted central cores, and a low correlation between neighboring layers arising from dispersive forces between the end groups (methacrylic group and alkyl chain) of the monomer. On the other hand, the trans-cis isomerization of monomers is induced in solution by irradiating with a UV lamp. High cis-isomer contents (≥96 %) are obtained at the photostationary state, which is reached in a relatively short time (40 s). Copyright
