Structure of Langmuir-Blodgett Films of Star-Shaped Oligomeric Discogens

We have used atomic force microscopy (AFM) and X-ray diffraction (XRD) to study ultrathin films of star-shaped oligomeric molecules with mesogenic triphenylene subunits. At the air-water interface, the molecules undergo a conformational change such that the peripheral triphenylene substituents sit perpendicular to, and the central core sits parallel to, the interface. AFM measurements indicate that the conformation of the molecules is preserved upon transfer to a solid substrate and that the triphenylene subunits are organized in columns with average alignment along the direction of deposition. XRD shows that there is a 40 o distribution of column orientations, centered on the direction of deposition