1009573-83-4Relevant academic research and scientific papers
Self-organization of phthalocyanine-[60]fullerene dyads in liquid crystals
De La Escosura, Andres,Martinez-Diaz, M. Victoria,Barbera, Joaquin,Torres, Tomas
, p. 1475 - 1480 (2008)
(Chemical Equation Presented) The use of blends in which a mesogen induces mesomorphism into a non-mesogenic compound has made possible the self-organization of phthalocyanine - [60]fullerene (Pc-C60) dyads into liquid crystals. Pc-C60 dyads 1, 2, or 3, in which two photoactive units are brought together by a phenylenevinylene spacer, have been synthesized through a Heck reaction that links 4-vinylbenzaldehyde to a monoiodophthalocyanine precursor, followed by standard cycloaddition of azomethine ylides - generated from the formylPc derivative and N-methylglycine - to one of the double bonds of C60. The mesomorphic and thermal properties of different mixtures formed by the liquid-crystalline phthalocyanine 4 and dyads 1, 2, or 3 were examined using polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). DSC diagrams of the blends show clear transitions from the crystalline state to a mesophase, and the measured structural parameters obtained from the powder diffraction experiments are consistent with a discotic hexagonal columnar (Colh) structure. Considering that segregation in domains of separated molecules of Pc-C60 dyad and phthalocyanine 4 would preclude mesomorphism due 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 calculated density of the blend mesophases relative to the mesophase of pure compound 4 is important evidence in this direction.
