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Synthesis and Mesogenic Properties of New Schiff Bases Comprising Benzothiazole Moiety
1 , 2 , 3 , 4 , * 3
1  Department of Materials Science & Engineering, National Chiao Tung University, 1001 Ta- Hsueh Road, Hsinchu 300, Taiwan
2  Liquid Crystal Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
3  Department of Chemical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jln Universiti, Bandar Barat, Kampar, 31900 Perak, Malaysia
4  Department of Science, Faculty of Engineering & Science, Universiti Tunku Abdul Rahman, Jalan Genting Klang, Setapak, 53300 Kuala Lumpur, Malaysia

Abstract: A new homologous series of mesogen, 6-ethoxy-2-(4- alkanoyloxybenzylideneamino)benzothiazoles with even number of carbons (n = 6, 8, 10, 12, 14, 16, 18) at terminal ester chain have been successfully synthesized and isolated. The structure of the title compound was confirmed using elemental analysis and various spectroscopic techniques including FT-IR, 1H NMR and 13C NMR and EI-MS. Phase transition temperatures and thermal data were determined using differential scanning calorimetry. The textures of mesophases were observed under optical polarizing microscope attached with a Linkam hotstage. All the compounds are enantiotropic liquid crystals. While n-hexanoyloxy and n-octanoyloxy derivatives exhibited nematic, ndecanoyloxy to n-octadecanoyloxy derivatives showed smectic C and nematic phases.
Keywords: Liquid crystal, Benzothiazole, Schiff bases, Nematic, Smectic C