V. Prasad et al., A novel series of anthraquinone-based discotic liquid crystals with bulky substituents: synthesis and characterization, LIQ CRYST, 27(8), 2000, pp. 1075-1085
A novel series of anthraquinone-based discotic liquid crystals with bulky s
ubstituents? namely 1,5-dibenzyloxy-2,3,6,7-tetraalkyloxy-9, has been synth
esized starting from gallic acid. This is, to our knowledge, the first exam
ple of bulky substitution in a discotic C-2-symmetric molecule forming colu
mnar phases. Except for the lowest homologue, all members of this series ar
e found to exhibit columnar mesophases; the low temperature mesophase appea
rs to be three-dimensionally ordered whereas the high temperature mesophase
is hexagonal columnar (Col(h)). We find that the introduction of benzyl su
bstituents for alkyl chains (in the 1,5-positions) on the anthraquinone hex
aalkoxylates stabilizes the three-dimensionally ordered phase, whereas it d
estabilizes the Col(h) phase, compared with the anthraquinone hexaalkoxylat
es. Interestingly, the three-dimensionally ordered phase extends down to -
50 degrees C, making these new derivatives suitable for device applications
.