The use of blends in which a mesogen induces mesomorphism into a non-mesogenic compound hasma
de possible the self-organization of phthalocyanine-[60]fullerene (Pc-C
60) dyads into liquid crystals.Pc-C
60 dyads
1,
2, or
3, in which two photoactive units are brought together by a phenylenevinylenespacer, have been synthesized through a Heck reaction that links 4-vinylbenzal
dehy
de to a monoiodophthalocyanine precursor, followed by standard cycloaddition of azomethine yli
des-generated from theformylPc
derivative and
N-methylglycine-to one of the double bonds of C
60. The mesomorphic andthermal properties of different mixtures
formed by the liquid-crystalline phthalocyanine
4 and dyads
1,
2, or
3 were examined using po
larizing optical microscopy (POM), differential scanning calorimetry(DSC), and X-ray diffraction (XRD). DSC diagrams of the blends show clear transitions from the crystallinestate to a mesophase, and the measured structural parameters obtained from the pow
der diffractionexperiments are consistent with a discotic hexagonal columnar (Col
h) structure. Consi
dering that segregationin domains of separated molecules of Pc-C
60 dyad and phthalocyanine
4 would preclu
de mesomorphismdue to the mismatch in the column diameter and to the
lack of mesogenic character of the pure dyads,a predominance of alternating stacking is proposed. Additionally, the observed
decrease in the calcu
lated
density of the blend mesophases re
lative to the mesophase of pure compound
4 is important evi
dence inthis direction.