Structure of monolayers of copper tetra-(3-nitro-5-tert-buty1)-phthalocyanine at the air-water interface

The structure of floating layers of soluble copper tetra-(3-nitro-5-tert-bu tyl)-phthalocyanine (CuPc*) is studied through surface pressure-area (pi -A ) isotherms measured at various initial surface concentrations (N-0) of CuP c*. In the gaseous layers, the CuPc* molecules are surrounded by a hydratio n sphere. Condensation of the layers under compression results in an increa se in the tilt angle of the CuPc* molecules relative to the air-water inter face. Though it is accompanied by a loss of weakly bound water, an inner pa rt of the hydration sphere sustains compression and enters the condensed la yers. Depending on the No and pi values, the molecular tilt angle ranges fr om 30 to 90 degrees indicating the phase states of the beta-, alpha-, and x -types. The different nature of the bilayers formed through compression of the rare monolayers and through spreading of large amounts of CuPc* is stat ed.