DISCOTIC TWIN AND TRIPLE MOLECULES WITH CHARGE-TRANSFER INTERACTIONS IN LANGMUIR-BLODGETT-FILMS

X-ray and atomic force microscopy observations reveal features of the surface morphology of Langmuir-Blodgett (LB) films from discotic donor -acceptor molecules with strong core-to-core interactions caused by a charge-transfer (CT) complexation. The compounds are designed to be tw in and triple molecules composed of chemically connected donor (triphe nylene) and acceptor (trinitrofluorenone) fragments which display liqu id crystalline structure in the bulk state. The LB films from these co mpounds possess edge-on orientation of molecules within monolayers wit h a smooth surface on a submicron scale but with substantial macroscop ic imperfections. These imperfections are represented by the micron si ze fractures and ruptures apparently caused by local deformations and tensions during transfer of the discotic monolayers from the air-water interface to a solid substrate. It is suggested that this is due to t he excessive rigidity of the monolayers caused by the stiffness of the columns with positional intracolumnar ordering enhanced by the strong intracolumnar CT interactions.