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Issue 7, 2000
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Extended triphenylenes: synthesis, mesomorphic properties and molecularly resolved scanning tunneling microscopy images of hexakis(dialkoxyphenyl)triphenylenes and dodeca(alkoxy)tris(triphenylenylene)s

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Abstract

Palladium-catalyzed cross-coupling between 3,4-dialkoxyphenylboronic acids (1ad) and 2,3,6,7,10,11-hexabromotriphenylene (2) provided 2,3,6,7,10,11-hexakis[3,4-bis(alkoxy)phenyl]triphenylenes, C18H6[C6H3(OCnH2n + 1)2]6 where n = 6, 8, 10, and 12 (3ad). Cyclodehydrogenation of the aryl-substituted triphenylenes 3ad using ferric chloride oxidation followed by methanol reduction produced 6,6′,6″,7,7′,7″,10,10′,10″,11,11′,11″-dodecaalkoxy-2,3′:3,2″:2′,3″-tris(triphenylenylene)s, C54H18(OCnH2n + 1)12 where n = 6, 8, 10, and 12 (4ad). The mesomorphic properties of the compounds 3ad and 4ad were investigated by differential scanning calorimetry (DSC) measurements, polarizing microscopy, and wide angle X-ray diffraction (WAXD). The triphenylenes 3ad exhibited a columnar mesophase in the range of 111–126, 85–104, 74–103, and 47–101 °C, respectively. Upon oxidation of the moiety, the columnar mesophases shift to higher temperatures and exist in a much broader range of temperatures: for the tris(triphenylenylene)s 4ad, they have been observed in the range of 180–430, 150–370, 120–322, and 104–306 °C, respectively. Finally, the self-assembly at the interface between a solution of 4c and a graphite substrate has been studied by scanning tunneling microscopy. Molecularly resolved imaging revealed a highly ordered monolayer exhibiting a two-dimensional hexagonal lattice.

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Publication details

The article was received on 11 Feb 2000, accepted on 17 Apr 2000 and first published on 13 Jun 2000


Article type: Paper
DOI: 10.1039/B001162M
Citation: J. Mater. Chem., 2000,10, 1519-1525
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    Extended triphenylenes: synthesis, mesomorphic properties and molecularly resolved scanning tunneling microscopy images of hexakis(dialkoxyphenyl)triphenylenes and dodeca(alkoxy)tris(triphenylenylene)s

    T. Yatabe, M. A. Harbison, J. D. Brand, M. Wagner, K. Müllen, P. Samorí and J. P. Rabe, J. Mater. Chem., 2000, 10, 1519
    DOI: 10.1039/B001162M

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