9315341 Heiney Discotic liquid crystals are generally composed of organic molecules with a rigid disk-shaped core and 6-8 alkyl tails. Depending on the temperature and molecular geometry, these molecules can form either nematic phases or columnar structures with long-range intercolumnar order and only short- range intracolumnar order. Such columnar structures represent a new ordering of dimensionalities for a condenssd state of matter: they are ordered in two dimensions and disordered in one. Further, discotic donor-acceptor complexes formed by doping with an electron acceptor such as iodine may combine the electrical properties of semiconductors or conductors with the anisotropic mechanical, optical, and structural properties of liquid crystals. Discogenic molecules can aggregate at the air-water interface to form Langmuir films, and thence be transferred to solid substrates to form Langmuir-Blodgett films. The columnar structure of these materials is reflected in transport anisotropy. Such thin films are of interest as model low-dimensional systems and for display applications and the development of pressure sensors. In this research, studies on discotic liquid crystals are conducted to correlate the structure of bulk phases, the structure of thin films, and the conductivity of both three-dimensional and two- dimensional materials. The primary tools employed will be x-ray diffraction, atomic force microscopy, and voltammetry, in conjunction with standard characterization by optical microscopy and calorimetry. The materials studied will include triphenylene and truxene derivatives, hexacyclens, and phthalocyanine derivatives; the latter are synthetic analogs of porphyrins that are of interest because of their electrical, optical, and catalytic properties. Additionally, the properties of newly conceived heptameric "supradisks" and tubular compounds will be characterized and explored. ***
