Langmuir-Blodgett films of long-chain derivatives of amino acid containing aromatic rings

Abstract

For long-chain derivatives of amino acid containing naphthalene, the arrangement of the chromophore in Langmuir-Blodgett (LB) films was examined by circular dichroism (CD) together with UV absorption and fluorescence spectroscopies. The monolayer of ϵ N-stearoyl- L-lysyl- L-1-naphthylalanine methylester exhibits a region of transition from expanded to condensed states. The absorption spectra of the LB films show a slight red shift of 1B b and 1L a bands for naphthalene in comparison with the solution spectrum. The CD spectra of the LB films vary significantly with surface pressure and type of deposition. In particular, the Y-type LB films prepared at high pressure beyond the transition region show a strong Cotton effect due to the interaction of the chromophore. The multilayers prepared using the horizontal lifting method show a weaker Cotton effect than conventional LB films. Therefore the Cotton effect is ascribed to the strong interlayer interaction of the chromophore together with intralayer interaction.