Structural characterization of Langmuir-Blodgett films of nickel complexes with amphiphilic compounds

Spreading monolayers and Langmuir-Blodgett (LB) multilayers are appropriate supramolecular structures for molecular recognition. Specifically oriented ligands in the head group of the amphiphiles in the monolayer can selectively interact with the ions to be detected in solution. We investigated spreading monolayers of dioctadecyldithiocarbamate (DODTC) and nonadecylpiridyne (NDP), on subphases containing transition metal ions, by means of π- and Δ V-area isotherms. UV-Vis spectroscopy absorption and electron spectroscopy for chemical analysis measurements performed on LB films of DODTC and NDP transferred from subphases containing nickel ions indicated that the Ni ions combine with the monolayer to form stable adducts. The structure of the resulting LB films were further characterized using X-ray diffraction and atomic force microscopy. Both experiments indicated that in the presence of the transition metal ion there is a drastic variation in the structural organization of the monolayers and in the morphology of the LB films.