Formation of mono- and multilayers of metal complexes of 4-(((10,12-pentacosadiynoyl)oxy)methyl)pyridine

Abstract

The monolayer properties of the amphiphile, 4-(((10,12-pentacosadiynoyl)oxy)methyl)pyridine have been studied by measuring the surface pressure–area isotherms. The amphiphile forms stable monolayers at the air–water interface and protonation of the monolayers occurs at pH values of 3.00 or lower. Addition of Cu(II) to the subphase (0.5–50 mM) causes an increase of the pressure ( Π c) at which the phase transition from the liquid-expanded (LE) to liquid-condensed (LC) phase appeared, suggesting that complexation in the monolayer has occurred. This complexation behaviour is strongly influenced by the Cu(II) concentration, the kind of counterion, and the ionic strength of the subphase. Multilayers of the amphiphile can only be built up when the subphase contained Cu(II) ions. The presence of Cu(II) ions is confirmed by means of X-ray photoelectron spectroscopy measurements, from which it can be concluded that indeed complexation in the monolayer has taken place. Fourier transform infrared spectroscopy and small-angle X-ray reflection measurements revealed that the multilayers have a regular layer structure with a bilayer spacing of 41.3 Å. Upon polymerisation by means of exposure to UV light, the regular layer structure of the multilayers is preserved but decreased to 40.5 Å. A maximum degree of polymerisation is reached after 30 min of UV irradiation.