Investigation of 2-(Docosylamino)-5-nitropyridine Monolayers and Langmuir−Blodgett Films

Abstract

The behavior of 2-(docosylamino)-5-nitropyridine (DCANP) spreading monolayers was investigated as a function of temperature, pH, and subphase composition. The interactions of DCANP monolayers with copper ions dissolved into the subphase at different concentrations were also studied. The investigations were carried out by measuring surface pressure and surface potential−area isotherms. Langmuir−Blodgett (LB) films transferred from pure water and copper aqueous subphases were also studied by Fourier transform infrared (FTIR), UV−vis, and electron paramagnetic resonance (EPR) spectroscopies, X-ray photoelectron spectroscopy (XPS), ellipsometry, and refractive index measurements. The interactions between copper ions and DCANP molecules were investigated by means of various techniques in the bulk phase, in monolayers, and in LB films. Clear evidence of interactions between DCANP and copper ions was provided only from EPR spectroscopy in the LB films, because of the very small molar ratio of bound/free DCANP in the LB films. The refractive index of Cu-doped LB films was shown to be increased by the presence of metal ions.

Complexation of Ferrous and Cupric Ions by Phenanthroline and Terpyridine Langmuir Films

“…The interaction between Langmuir films and metal ions has been of interest as a model for natural systems as well as a selectivity factor in designing sensing devices. − A variety of amphiphile monolayers based on mono- and multidentate ligands have been studied in the presence of metal ions in the subphase. − Surveying these studies reveals that most of the investigated Langmuir films do not exhibit high selectivity toward transition-metal ions as has been evidenced by the small effect of the ions on the isotherm. Not surprisingly, cupric ions usually showed the highest affinity toward Langmuir films, which could be attributed to the square-planar complex that is relatively easily formed at the water−air interface. − However, to the best of our knowledge, the formation of octahedral complexes that prevail among many first raw transition metals (e.g., Fe 2+ and Co 2+ ) has not been reported at the water−air interface.…”