Synthesis and Characterization of Nonsymmetric Liquid Crystal Dimer Containing Biphenyl and Azobenzene Moiety

Abstract

Calamitic liquid crystalline dimer containing azobenzene moiety and a decyloxy biphenyl linked by flexible spacers {4-[7-(4′-decyloxy-biphenyl-4-yloxy)-alkyloxy]-phenyl}-(4-decyl-phenyl)-diazene has been synthesized and characterized by spectroscopic methods. The transition temperatures and phase behaviours were studied by Differential Scanning Calorimeter (DSC) and Polarizing Optical Microscope (POM). The synthesized compounds exhibited enantiotropic liquid crystal phase with higher spacer display nematic and smectic C phases while lower spacer shows nematic and smectic A phases.

Effect of exchange of terminal substituents on the mesophase behaviour of some azo/ester compounds

“…These results can be explained in terms of two competitive effects: polarisability anisotropy and repulsive forces. The polarisability anisotropy (Δα M ) of the whole molecular structure (excluding the substituent X), calculated for compounds of group I as well as those reported previously for compounds III and IV, revealed that Δα M for compounds I and III increases as the alkoxy chain is lengthened, [25] whereas for compounds IV the reverse is true. [37] In the case of phenyl benzoate molecules (compounds III), the increase in Δα M with chain length reflects the increase in the lateral aliphatic-aliphatic interactions of the rod-shaped molecules, which adds to the dipole-dipole interactions, as a result of increasing the n-alkane character.…”

“…[13][14][15][16][17] Liquid crystal materials bearing azo/ester central linkages and middle and terminal phenyl rings substituted with groups of different polarity as well as nalkoxy group on the other end of the molecule were reported. [18][19][20][21][22][23][24][25][26][27] In previous work [28] in this laboratory, the effect of compact terminal substituent (X), as well as the terminal alkoxy (RO-) group, of varying chain length, on the mesophase behaviour of compounds of the type 4-(4′-substituted phenylazo) phenyl 4″-alkoxybenzoates (IIn af ) was studied. In that work, [28] it was observed that the stability of the mesophase is augmented by an increase in the polarity and/or polarisability of the mesogenic part of the molecule, which is definitely affected by the polarity of the substituent, and its position, which would accordingly affect the polarity of the whole molecular structure by the way the polar substituents electronically interact with the remainder of the molecule.…”

Azo-Dyes-Grafted Oligosaccharides—From Synthesis to Applications

“…For the diazo coupling, several phenolic compounds can provide good electron-enriched substrates. We can cite for example the nude phenol [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ], but also natural compound such as salicylaldehyde [ 25 , 26 , 27 ], vanillin [ 28 , 29 ], or even resorcinol [ 30 , 31 ].…”

Amphiphilic azobenzenes: Antibacterial activities and biophysical investigation of their interaction with bacterial membrane lipids

“…The emergence of nosocomial multi-drug resistant (MDR) bacterial strains is a growing concern in hospitals and underlines the urgent need for the development of novel antibacterial agents [1,2]. The azo compounds are used in a wide range of applications such as surfactants [3][4][5], catalysts [6], gelators [7], and liquid crystals [8,9]. Recently, azo-amphiphiles have been shown to exhibit a high biocide potential, especially if they contain a cationic head group such as quaternary ammonium salt.…”