Perhydroazulenes - A New Class of Liquid Crystalline Materials

Abstract

A new class of mesogenic compounds, the perhydroazulenes, carrying substituents in their para positions (HAZ derivatives), has been synthesized. The new liquid crystalline materials display a broad enantiotropic nemantic mesophase slightly above room temperature without any additional smectic phase. Their physical properties reveal that the perhydroazulene moiety can replace the currently often used cyclohexyl and biscyclohexyl units in liquid crystalline materials.

Key words

liquid crystals - perhydrogenated azulenes - nematic materials - electrooptical displays

References and Notes

• 1 Hussain Z. Hopf H. Pohl L. Oeser Th. Fischer AK. Jones PG. Eur J. Org. Chem.  2006,  5555 
• 2 Krause GA. Landgrebe K. Synthesis  1984,  885 
• 3 Nagai M. Lazor J. Wilcox CS. J. Org. Chem.  1990,  55:  3440 
• 4 Weinhardt KK. Tetrahedron Lett.  1984,  25:  1761 
• 6 White RD. Wood JL. Org. Lett.  2001,  3:  1825 
• 8a Bahadur B. Liquid Crystals Applications and Uses   Vol. 1:  World Scientific; Singapore: 1990. 
• 8b Becker W. Liquid Crystal Newsletter  2000,  15:  13 
• 8c Scheuble BS. Gehlhaar T. Liquid Crystal Newsletter  2000,  15:  39 
• 8d For an excellent recent review, see: Kirsch P. Bremer M. Angew. Chem. Int. Ed.  2000,  39:  4216 ; Angew. Chem. 2000, 112, 4384
• 8e Heckmeier M. Dunmur D. Stegemeyer H. Crystals that Flow   Taylor and Francis; London: 2004.  Sect. D.
• 9a Pauluth D. Tarumi K. J. Mater. Chem.  2004,  14:  1219 
• 9b Iwata Y. Naito H. Inoue M. Ichinose H. Klasen-Memmer M. Tarumi K. Jpn. J. Appl. Phys.  2004,  43 (12B):  L1588 
• 10a Klasen M. Götz A. Liquid Crystal Newsletter  1999,  14:  22 
• 10b Tarumi K. Heckmeier M. Liquid Crystal Newsletter  2000,  15:  30 
• 11 Goulding M. Reiffenrath V. Hirschmann H. Liquid Crystal Newsletter  2001,  16:  33 

5

Perhydroazulene-2,6-dione Ethylene Ketal 9
^¹H NMR (400.14 MHz, CDCl₃): δ = 3.86 (s, 4 H), 2.30-2.48 (m, 4 H), 1.92-2.04 (m, 2 H), 1.77-1.88 (m, 2 H), 1.51-1.69 (m, 6 H) ppm. ^¹³C NMR (100.62 MHz, CDCl₃): δ = 219.2, 111.5, 64.3 (+), 64.2 (+), 45.5 (+), 39.0 (-), 36.6 (+), 25.8 (+) ppm. MS (IE): m/z (%) = 210 (9) [M⁺], 126 (5), 99 (100), 86 (10), 55 (8); IR (diamond ATR): ν = 2990, 2931, 2880, 1731 cm^-¹. UV (MeCN): λ_max = 284 nm.

7

Liquid Crystalline Derivative 16
^¹H NMR (300.13 MHz, CDCl₃): δ = 6.86 (ddd, 1 H, J ₁  = 0.3 Hz, J ₂ = 2.4 Hz, J ₃ = 8.9 Hz), 6.47 (dd, 1 H, J ₁ = 2.0 Hz, J ₂ = 7.6 Hz), 4.08 (q, 2 H, J = 7.0 Hz), 2.96-3.12 (m, 1 H), 2.19-2.38 (m, 2 H), 1.59-1.96 (m, 12 H), 1.43 (t, 3 H, J = 7.0 Hz), 1.23-1.38 (m, 4 H), 0.81-0.99 (m, 4 H) ppm. ^¹³C NMR (75.47 MHz, CDCl₃): δ = 149.1 (dd, J ₁ = 10.3 Hz, J ₂ = 245.0 Hz), 145.9 (dd, J ₁ = 3.0 Hz, J ₂ = 8.2 Hz), 141.5 (dd, J ₁ = 15.3 Hz, J ₂ = 246.5 Hz), 129.1 (dd, J ₁ = 1.5 Hz, J ₂ = 12.3 Hz), 120.9 (+, dd, J ₁ = 4.6 Hz, J ₂ = 6.0 Hz), 109.3 (+, d, J = 2.5 Hz), 65.4 (+), 40.8 (+), 39.8 (-), 39.5 (-), 37.9 (+), 37.5 (-), 31.8 (+), 29.2 (+), 21.9 (+), 14.8 (-), 14.4 (-) ppm. MS (IE): m/z (%) = 337 (22) [M + H⁺], 336 (100) [M⁺], 198 (13), 197 (20), 184 (52), 171 (14), 169 (12), 156 (36), 143 (24), 83 (15). IR (diamond ATR): ν = 2931, 2889, 2857, 1511, 1473, 1296, 1116, 1081, 805 cm^-¹. UV (CH₂Cl₂): λ_max = 229, 268 nm. For mp see Table  [¹] .