It is shown that trifluoroacetic acid (TFA) can form 1:1 molar complex
es with alkyloxy discotic compounds, thereby enhancing their mesomorph
ic properties. In particular, when hexa-alkyloxytriphenylenes (THEn) (
n being the number of carbons per side chain) are crystallized from, o
r mixed with, TFA, complexes are formed which exhibit the D-ho(Col(ho)
) mesophase, as do the neat THEn's, but with a broader range of therma
l stability and a higher degree of order. The mesophases of these comp
lexes are completely miscible with those of the neat compounds. Likewi
se, 1:1 mixtures of hexa-alkyloxytribenzocyclononene (TBCEn) and TFA y
ield complexes showing enhanced mesomorphic properties for the mesogen
ic homologues of this series and induced mesomorphism for the lower ho
mologues, which in the neat form are not mesogenic. The mesomorphic pr
operties of these TFA complexes with THEn (n=3-6) and with TBCEn (n=4-
6) are investigated by means of optical microscopy, differential scann
ing calorimetry, X-ray diffraction and NMR spectroscopy. It is suggest
ed that the enhancement of the mesomorphic properties is due to format
ion of oxonium ion complexes.