Organized Molecular Films from New Ferrocene-Containing Molecular Units

The design and synthesis of new amphiphilic ferrocene derivatives and their capability for forming Langmuir and Langmuir−Blodgett films are reported. The film formation at the air−water interface was followed by surface pressure−molecular area isotherm, surface potential−molecular area isotherm, and Brewster angle microscopy. The stability and structure of the transferred films were investigated by UV−vis spectroscopy and small angle X-ray experiments. Transfer ratios near unity were obtained. Two hydrophobic alkyl chains combined with either one or two hydrophilic functions gave stable and ordered films. One hydrophobic alkyl chain associated to one hydrophilic headgroup required the presence of an intercalant for obtaining organized molecular films. This behavior clearly illustrated the key role played by the three-dimensional structure of the ferrocene unit which tends to decrease the intermolecular interactions because of its bulkiness; this is in agreement with results reported for ferrocene-containing thermotropic liquid crystals (Deschenaux, R.; Goodby, J. W. In <i>Ferrocenes:  Homogeneous Catalysis, Organic Synthesis, Materials Science</i>; Togni, A., Hayashi, T. Eds.; VCH Verlagsgesellschaft:  Weinheim, 1995; pp 471−495).