期刊
JOURNAL OF PORPHYRINS AND PHTHALOCYANINES
卷 22, 期 8, 页码 693-715出版社
WORLD SCI PUBL CO INC
DOI: 10.1142/S108842461850092X
关键词
phthalocyanine; fullerene; columnar mesophase; homeotropic alignment; helical supramolecular structure; substitution position effect
We have synthesized twelve novel discotic columnar liquid crystals based on a phenoxy-group-substituted phthalocyaninato copper(II) complex having the same alkoxy chain of C16H33O at different positions in the phenoxy group: the parent compounds {0a similar to 0c-16} and the OH-substituted compounds {3a similar to 3c-16}, the OFBA-substituted compounds {2a similar to 2c-16} and the C-60-substituted dyads {1a similar to 1c-16}. The letters of a, b and c mean substitution positions of C16H33O group at m-, p-and m, p-, respectively. We have investigated the influence of both substitution position of the alkoxy chains and the kind of terminal groups (OH, OFBA and C-60) on the mesomorphism and the helical supramolecular structure, by using DSC, POM and temperature-variable small angle X-ray diffraction measurements. As a result, an additional big peak (Peak H) tends to appear at around 2 theta = 1.1 degrees in the X-ray diffraction patterns only for the dyads {1a similar to 1c-16} but not for the other compounds, {0a similar to 0c-16}, {3a similar to 3c-16} and {2a similar to 2c-16}, regardless of the substitution positions of the alkoxy group. Moreover, we revealed that both the m-substituted derivative 1a-16 and the m, p-substituted derivative 1c-16 gave Peak H, but that only the p-substituted derivative 1b-16 did not give Peak H among these three dyads {1a similar to 1c-16}. From the temperature-variable small angle X-ray diffraction measurements for the m, p-substituted derivative 1c-16 using two different sample preparation methods, we proved that the Peak H originates from a helical pitch of fullerenes. We also pointed out that the m-substituted long alkoxy chains are at least needed to form the helical supramolecular structure in the present (PhO)(6)PcM-C-60-based dyads.
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