Effect of Molecular Structure on Mesomorphism. Two Series of Novel Methylene-Bridged Liquid Crystals

Azoester-based H-shaped symmetrical mesogenic dimers containing – CH3/–OCH3terminal substituent

“…A literature survey reveals that the H-shaped dimesogenic compounds are scanty. Griffin et al [6,7] reported the first compounds of ligated twins in which two mesogenic units are connected by methylene spacer exhibiting monotropic smectic C and nematic phases. Weissflog et al [8] have synthesized new sulphur-containing twins.…”

“…Elemental analysis: found(%): C 72.71, H 7.99 and N 4.54; calculated for C 78 H 102 N 4 O 12 (%): C 72.78, H 7.93 and N 4.35. , cm À1 (KBr): 2940, 2830 (-CH 2 -COOAr), 1740, 1707 (Ar-COO-Ar), 1622 (-N¼N-), 1583, 1502, 1471, 1421, 1315, 1251 (Ar-O-C), 1166, 1140, 1109, 1024, 893, 840. H 0.86 (t, 6H, 2 X -CH 3 ), 1.26-1.55 (m, 56H, 2 X Ar-O-C-C-(CH 2 -) 13 at C-4 0 and Ar-OCO-C-(CH 2 -) 2 at C-1), 1.82-2.01 (m, 4H, 2 X Ar-O-C-CH 2 -at C-4 0 ), 2.33 (t, 6H, 2 X Ar-OCO-CH 2 -at C-1), 3.80-3.90 (s, 6H, 2 X Ar-O-CH 3 ), 4.03 (t, 4H, 2 X Ar-O-CH 2 -at C-4 0 ),6.87 (d, J ¼ 9.0 Hz, 4H, 2 X ArH at C-3 0 and C-5 0 ), 6.96-7.00 (m, 4H, 2 X ArH at C-3 00 and C-5 00 ), 7.70 (d, J ¼ 9.0 Hz, 4H, 2 X ArH at C-4 and C-6), 7.92 (d, J ¼ 8.8 Hz, 4H, 2 X ArH at C-2 00 and C-6 00 ), 8.14 (d, J ¼ 8.9 Hz, 2H, 2 X ArH at C-3), 8.17 (d, J ¼ 8.8 Hz, 4H, 2 X ArH at C-2 0 and C-6 0 ).…”