Spectral and thermodynamic characterization of bacteriochlorophyll c and dipalmitoylphosphatidylcholine in the binary mixed monolayers

The spectral and thermodynamic properties of bacteriochlorophyll c and dipalmitoylphosphatidylcholine in binary mixed monolayers have been investigated. The model system of biological membrane was built up of a mixture of phospholipids and pigments dissolved in chloroform, at several mole ratios. The isotherms of these samples were recorded and then the monomolecular layers on quartz plate were produced. For the Langmuir layer obtained on the air–water interface the thermodynamic parameters were calculated. Additionally, by means of the absorption spectroscopy methods in natural and polarized light, pigment–pigment and pigment–lipid interactions were studied. The information about the average surface per molecule, aggregation properties and the molecular orientation of pigments in Langmuir–Blodgett layers, was obtained.