EFFECTS OF CHAIN-LENGTH AND POLYMER COMPLEXATION ON THE AGGREGATION AND ORIENTATION OF HEMICYANINE MONOLAYERS

The effect of complexation by a polyanion on the structure of air-wate r monolayers of 4-[4-(didecylamino)styryl]-N-methylpyridinium iodide ( 10ASP) and 4-[4-(dihexadecylamino)styryl]-N-methylpyridinium iodide (1 6ASP) was studied by recording reflection spectra as a function of com pression. In the case of water subphases, 16ASP displayed a coexistenc e of monomer and aggregate at all surface pressures while 10ASP showed no aggregation. For both 10ASP and 16ASP on dextran sulfate solution subphases, only monomer was observed. In addition to preventing the fo rmation of aggregates, complexation by the polyanion altered the orien tation of the long axis of the chromophore to closer to the surface no rmal, as evidenced by changes in the absorption maximum.