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Arrays of Aligned Supramolecular Wires by Macroscopic Orientation of Columnar Discotic Mesophases

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journal contribution
posted on 2012-11-27, 00:00 authored by Hatice Duran, Brigitte Hartmann-Azanza, Martin Steinhart, Dominik Gehrig, Frédéric Laquai, Xinliang Feng, Klaus Müllen, Hans-Jürgen Butt, George Floudas
Structure formation, phase behavior, and dynamics of mono-bromo hexa-peri-hexabenzocoronene (HBC-Br) are strongly affected by the confinement of cylindrical nanopores with rigid walls. Using self-ordered nanoporous anodic aluminum oxide (AAO)-containing arrays of aligned nanopores with narrow size distribution as a confining matrix, pronounced alignment of the HBC-Br columns along the nanopore axes was found to be independent of the pore diameter. Hence, arrays of one-dimensional supramolecular HBC-Br wires with the columns uniformly oriented along the wire axes on a macroscopic scale were obtained, unlike with discotics bearing smaller cores. The formation of the crystalline herringbone structure is shifted to lower temperatures in nanopores with diameters of a few hundred nanometers, whereas the formation of this low-temperature phase is completely suppressed when the pore diameter is below 20 lattice parameters. Moreover, the cylindrical confinement affects the disk axial dynamics as well as the distribution of relaxation times.