Amphiphilic Hairy Disks with Branched Hydrophilic Tails and a Hexa-peri-hexabenzocoronene Core

• Published in: Journal of the American Chemical Society Vol. 124; no. 31; pp. 9121 - 9128
• Main Authors: LEE, Myongsoo, KIM, Jung-Woo, PELESHANKO, Sergiy, LARSON, Kirsten, YOO, Yong-Sik, VAKNIN, David, MARKUTSYA, Sergei, TSUKRUK, Vladimir V.
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 07.08.2002; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Experimental determinations of smectic, nematic, cholesteric, and other structures; Liquid crystals; Physical Sciences; Physics; Science & Technology; Structure of solids and liquids; crystallography; MIXTURES; MONODENDRONS; PHASE; BEHAVIOR; SCANNING PROBE MICROSCOPY; X-RAY-DIFFRACTION; DISCOTIC LIQUID-CRYSTALS; LANGMUIR-BLODGETT-FILMS; MONOLAYERS; Molecular packing; Liquid solid interface; Spectroscopic ellipsometry; Scanning probe microscopy; Surface segregation; Coronene derivatives; Experimental study; Amphiphilic compound; Discotic liquid crystals; Molecular orientation; Supramolecular structure; Monolayers; Molecular association; Benzenic compound; Molecular aggregation
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja017553+

Amphiphilic discotic molecules with hydrophilic side branches consisting of hexaphenyl hexa-peri-hexabenzocoronene and hexabiphenyl hexa-peri-hexabiphenylcoronene as the aromatic core and hexa-substituted oligoethers as the branched peripheral chains have been synthesized, and their microstructure has been characterized. The discotic molecules based on dibranched oligoether side chains have been observed to self-organize into a well-ordered hexagonal columnar structure within liquid crystalline phases, which possessed an exceptionally high thermal stability and an unusually wide temperature range over >300 degreesC. We suggest that a combination of the large lateral dimensions of the rigid cores and disordered structure of the oxygen-containing branches tails is a driving force to the formation of a highly ordered columnar structure in the bulk state with enhanced molecular segregation. In contrast to the thermotropic phase behavior that favors the formation of highly ordered columnar aggregates through a strong stacking interaction, the hexabenzocoronene cores are packed in a face-on arrangement at the air/water interface and on solid surfaces with surface domains composed of an array of 7 x 7 molecules. We suggest a crablike molecular conformation and cluster-segregated monolayers with 6-fold symmetry and unusual face-on packing on a solid surface. Preliminary spectroscopic studies in the bulk state have shown that the molecules based on a hexaaromatic-substituted core may serve as functional supramolecular materials with high energy transfer characteristic within the columns due to near-perfect columnar ordering, which is unchanged over a wide temperature range. We believe that an absence of the crystallization phenomenon of side-branched oligoether chains is critical for the formation of long-range columnar ordering with strong intracolumnar correlation of conjugated disks important for high carrier mobility.