STRUCTURAL INVESTIGATIONS OF DONOR-ACCEPTOR-SUBSTITUTED POLYENES

In this study investigations of Langmuir-Blodgett films of donor-acceptor substituted polyenes with long aliphatic chains are carried out. Monolayer film formation of 7-N,N-dioctylaminophenyl-7,8'-diapocarotene-8'-al (DAPC) has been observed and characterized on the water surface by pressure-area isotherms. The films were transferred to a variety of substrates, To determine the thickness and dielectric constant, surface plasmon resonance measurements were applied. The theoretical fit of the SPR results yielded a thickness of 14 angstrom per monolayer. Molecular resolution of DAPC molecules has been obtained by scanning tunnelling microscope investigations for the first time. The images revealed structures with two different periodicities. These results coupled to IR analysis, show that the conjugated chains are deposited parallel while the aliphatic chains are placed perpendicular to the surface.