Synthesis of unsymmetrical liquid crystalline compounds
Table 1. Elemental analysis for chalcone (series I) and isoxazoles (series II) derivatives.
Molecular
Formula
Elements
C
% Found
H
(% Calculated)
O
Sl. no
N
3e
3i
4e
4h
C30H42O4
C38H58O4
C30H41NO4
C36H53NO4
77.23 (77.21)
78.84 (78.85)
75.10 (75.12)
76.70 (76.69)
9.06 (9.07)
10.08 (10.10)
8.63 (8.62)
9.49 (9.47)
13.70 (13.71)
11.09 (11.06)
13.35 (13.34)
11.34 (11.35)
–
–
2.94 (2.92)
2.46 (2.48)
prepared as thin films between a glass slide and a glass cover (s, −OCH3, 3H), 4.04 (t, 2 × −OCH2, 4H), 6.87 (d, ArH,
slip. X-Ray data were collected on a Bruker diffractome- 1H), 6.94 (d, ArH, 2H), 7.15 (d, ArH, 2H), 7.42 (d, α-H,
ter. The UV–Visible absorption spectra for the mesomorphic chalcone), 7.73 (d, β-H, chalcone), 8.01 (d, ArH, 2H).
compounds were recorded in chloroform using Shimadzu 13C NMR (CDCl3, 400 MHz) δ: 14.1, 22.72, 22.80, 25.92,
UV/PC 160-A spectrophotometer in the spectral range 200– 25.97, 29.30, 29.40, 29.62, 29.72, 31.82, 31.96, 56.12,
800 nm. Transition temperatures and associated enthalpies 65.70, 68.76, 69.02, 112.12, 114.85, 114.95, 121.34, 122.12,
were determined by differential scanning calorimetry (DSC), 122.30, 126.60, 129.50, 130.50, 145.60, 149.82, 149.88,
using DSC Mettler TA 4000 at a scanning rate of 10◦C 165.20. Yield: 83%.
min−1 with controlled cooling accessory. The purity of the
compounds was checked by TLC and further confirmed
by elemental analysis (Table 1) using Perkin CHN ana-
lyzer; their results agreed favourably with the calculated
values.
2.5d 3-(4-(dodecyloxy)-3-methoxyphenyl)-1-(4-(octyloxy)
phenyl)prop-2-en-1-one (3h): FT-IR (cm−1): 2914, 1656,
1368, 1339, 1257. H NMR (CDCl3, 100 MHz) δ: 0.85 (t,
1
-CH3, 6H), 1.27 (m, −CH2, 25H), 1.41 (m, −CH2, 4H),
1.85 (m, −CH2, 4H), 3.78 (s, −OCH3, 3H), 4.02 (t,
2 × −OCH2, 4H), 6.85 (d, ArH, 1H), 6.95 (d, ArH, 2H),
7.18 (d, ArH, 2H), 7.42 (d, α-H, chalcone), 7.75 (d, β-H,
chalcone), 8.05 (d, ArH, 2H). 13C NMR (CDCl3, 400 MHz)
δ: 14.00, 14.12, 22.62, 22.65, 25.91, 25.97, 29.03, 29.11,
29.18, 29.51, 29.52, 29.60, 31.76, 31.89, 56.04, 56.21,
68.12, 68.27, 68.43, 69.21, 110.64, 112.45, 114.27, 122.87,
123.03, 127.88, 130.76, 144.05, 149.53, 150.97, 162.92.
Yield: 80%.
2.5 Selected data
2.5a 3-(4-butoxy-3-methoxyphenyl)-1-(4-(octyloxy)phenyl)
prop-2-en-1-one (3c): FT-IR (cm−1): 2917, 1738, 1646,
1
1365, 1311, 1261. H NMR (CDCl3, 100 MHz) δ: 0.89 (t,
−CH3, 3H), 1.04 (t, −CH2, 3H), 1.29 (m, −CH2, 10H), 1.39
(m, −CH2, 2H), 1.88 (m, −CH2, 4H), 3.92 (s, −OCH3, 3H),
4.06 (t, 2 × −OCH2, 4H), 6.87 (d, ArH, 1H), 6.95 (d, ArH,
2H), 7.18 (d, ArH, 2H), 7.38 (d, α-H, chalcone), 7.73 (d, β-H,
chalcone), 8.01 (d, ArH, 2H). 13C NMR (CDCl3, 100 MHz)
δ: 10.32, 10.42, 14.00, 22.37, 22.41, 25.96, 29.10, 29.18,
29.29, 31.76, 56.03, 56.20, 68.17, 68.27, 70.47, 110.67,
110.80, 112.49, 114.20, 114.25, 119.68, 119.82, 122.82,
122.96, 127.90, 130.62, 130.72, 131.11, 144.01, 144.16,
149.52, 150.93, 162.90, 188.70. Yield: 88%.
2.5e 5-(4-ethoxy-3-methoxyphenyl)-3-(4-(octyloxy)phenyl)
isoxazole (4a): FT-IR (cm−1): 3454, 2917, 1613, 1583,
1304, 1251. 1H NMR (CDCl3, 400 MHz) δ: 0.88 (t, −CH3,
3H), 1.29 (m, −CH2, 8H), 1.49 (m, −CH2, 2H), 3.86 (s,
−OCH3, 3H), 3.98 (t, −OCH2, 2H), 4.14 (t, −OCH2, 2H),
6.64 (d, 1H), 6.94 (m, ArH, 3H), 7.45 (dd, J=8 Hz, ArH, 2H),
7.75 (dd, J=8.8 Hz, ArH, 2H). 13C NMR (CDCl3, 100 MHz)
δ: 14.20, 14.70, 22.70, 25.90, 29.23, 29.56, 31.87, 56.12,
64.89, 68.72, 98.36, 108.50, 111.12, 114.93, 114.98, 119.28,
119.87, 122.90, 128.20, 130. 20, 150.40, 150.67, 159.40,
162.04, 169.35. LCMS: 424.34 [M+H]+; Yield: 78%.
2.5b 3-(3-methoxy-4-(pentyloxy)phenyl)-1-(4-(octyloxy)phenyl)
prop-2-en-1-one (3d): FT-IR (cm−1): 2914, 1656, 1365,
1320, 1261. 1H NMR (CDCl3, 100 MHz) δ: 0.89 (t, −CH3,
6H), 1.37 (m, −CH2, 15H), 1.86 (m, −CH2, 4H), 3.92 (s,
−OCH3, 3H), 4.03 (t, 2 × −OCH2, 4H), 6.88 (d, ArH, 1H),
6.97 (d, ArH, 2H), 7.18 (d, ArH, 2H), 7.35 (d, α-H, chal-
cone), 7.77 (d, β-H, chalcone), 8.04 (d, ArH, 2H). 13C NMR
(CDCl3, 400 MHz) δ: 14.10, 14.03, 22.70, 22.78, 25.91,
28.14, 29.32, 29.37, 29.60, 29.64, 31.19, 56.10, 68.70, 69.00,
111.12, 114.70, 118.2, 122.30, 126.70, 129.60, 130.60,
130.71, 145.1, 149.83, 149.81, 165.22, 189.89. Yield: 82%.
2.5f 5-(4-(hexyloxy)-3-methoxyphenyl)-3-(4-(octyloxy)phenyl)
isoxazole (4e): FT-IR (cm−1): 2930, 2855, 1608, 1580, 1293,
1
1249. H NMR (CDCl3, 400 MHz) δ: 0.88 (t, −CH3, 6H),
1.35 (m, −CH2, 12H), 1.44 (m, −CH2, 4H), 1.80 (m, −CH2,
4H), 3.94 (s, −OCH3, 3H), 4.01 (t, −OCH2, 2H), 4.07 (t,
−OCH2, 2H), 6.65 (d, 1H), 6.94 (m, ArH, 3H), 7.44 (dd,
J=8 Hz, ArH, 2H), 7.77 (dd, J=8.8 Hz, ArH, 2H). 13C NMR
(CDCl3, 100 MHz) δ: 14.10, 14.23, 22.70, 22.78, 25.60,
2.5c 3-(4-(heptyloxy)-3-methoxyphenyl)-1-(4-(octyloxy)phenyl) 25.98, 29.33, 29.67, 29.72, 29.88, 31.80, 31.98, 56.12,
prop-2-en-1-one (3f): FT-IR (cm−1): 2914, 1650, 1360, 68.70, 69.10, 98.34, 108.50, 111.12, 114.80, 114.90, 119.72,
1318, 1268. 1H NMR (CDCl3, 100 MHz) δ: 0.88 (t, −CH3, 119.82, 122.91, 128.10, 128.23, 150.40, 150.62, 159.48.
6H), 1.34 (m, −CH2, 10H), 1.82 (m, −CH2, 4H), 3.92 LCMS: 480.12 [M+H]+; Yield: 75%.