Nematic and smectic mesophase formation by a novel triphenylene-azobenzene hybride molecule

Md Lutfor Rahman ,Mashita Yusoff ,Carsten Tschierske ,Karsten Pelz ,Ute Baumeister ,Sidik Silong 2

University Malaysia Sabah
Martin-Luther University Halle-Wittenburg
2University Putra Malaysia

A novel liquid crystal whose molecular structure consists of a disc-like triphenylene unit as central core and six rod-like azobenzenes as the peripheral units is reported. This molecule, 2,3,6,7,10,11-hexakis{[4-(4-acetylphenylazo)phenoxy]hexyloxy}triphenylene, was prepared by ferric chloride oxidative trimerisation of 1,2-bis{[4-(4-acetylphenylazo)phenoxy]hexyloxy}benzene. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. The existence of a nematic and a smectic A phase was confirmed by textures and X-ray diffraction. UV-Vis spectra show a significant absorption of the azobenzene mesogens at 392 and 460 nm, which would allow the use of this and related materials for photoinduced isomerization and reorientation of the azobenzene groups by using light sources in the visible range.

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