Thin Film Phase and Local Chirality of Surface-Bound MOP4 Nanofibers
F Balzer and C Rothel and HG Rubahn and A Lutzen and J Parisi and R Resel and M Schiek, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 7653-7661 (2016).
Vacuum deposition of the methoxy-functionalized p-quaterphenylene MOP4 on muscovite mica at elevated temperatures led to the formation of several ten micrometer long nanofibers. As shown by X-ray diffraction and polarized optical microscopy, the fibers are formed by lying molecules which grow epitaxially (point-on-line coincidence) along two directions on a single muscovite domain. The crystal structure of the fibers was induced by the substrate. Molecular packing was calculated by molecular dynamics simulations. A wetting layer from the lying molecules was observed using low-energy electron diffraction (LEED) that had a crystal structure different from that of the fibers. Transfer of the sample from a vacuum to ambient conditions led to dewetting and the formation of clusters from the lying molecules. The samples aged via Ostwald ripening due to the presence of water vapor, which was monitored by atomic force microscopy (AFM). The fibers represent chiral organization into single-handed aggregates of both handednesses, which is not affected by aging. On a global level, the sample remained achiral.
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