TY - JOUR
T1 - Synthesis and mesomorphic properties of 6-methoxy- and 6-ethoxy-2-(2- hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles
AU - Ha, Sie Tiong
AU - Koh, Teck Ming
AU - Yeap, Guan Yeow
AU - Lin, Hong-Cheu
AU - Lee, Siew Ling
AU - Win, Yip Foo
AU - Ong, Siew Teng
PY - 2010/11/1
Y1 - 2010/11/1
N2 - Two new series of Schiff base thermotropic liquid crystals, 6-methoxy-2-(2-hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles and 6-ethoxy-2-(2-hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles, comprising different terminal groups, a methoxyl and ethoxyl group, respectively, were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as Fourier transform infrared (FTIR), 1H and 13C nuclear magnetic resources (NMR), and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry, optical polarizing microscopy, and thermogravimetric analysis. No liquid-crystal phases were observed for the short-chain members (n=2 and 3) in both series, and the remaining members all exhibited nematic phase with Schlieren or marble-like textures. Effects of the lateral hydroxyl group, terminal group, and the length of the terminal alkanoyloxy chain on the mesomorphic properties are discussed. Structure-property relationships were established upon comparison with other structurally related compounds.
AB - Two new series of Schiff base thermotropic liquid crystals, 6-methoxy-2-(2-hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles and 6-ethoxy-2-(2-hydroxy-4-alkanoyloxybenzylidenamino)benzothiazoles, comprising different terminal groups, a methoxyl and ethoxyl group, respectively, were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as Fourier transform infrared (FTIR), 1H and 13C nuclear magnetic resources (NMR), and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry, optical polarizing microscopy, and thermogravimetric analysis. No liquid-crystal phases were observed for the short-chain members (n=2 and 3) in both series, and the remaining members all exhibited nematic phase with Schlieren or marble-like textures. Effects of the lateral hydroxyl group, terminal group, and the length of the terminal alkanoyloxy chain on the mesomorphic properties are discussed. Structure-property relationships were established upon comparison with other structurally related compounds.
KW - Benzothiazole liquid crystals
KW - lateral hydroxyl group
KW - nematic
KW - structure-property relationship
KW - terminal group
UR - http://www.scopus.com/inward/record.url?scp=77958527603&partnerID=8YFLogxK
U2 - 10.1080/15421406.2010.504510
DO - 10.1080/15421406.2010.504510
M3 - Article
AN - SCOPUS:77958527603
VL - 528
SP - 10
EP - 22
JO - Molecular Crystals and Liquid Crystals
JF - Molecular Crystals and Liquid Crystals
SN - 1542-1406
ER -