Effect of the Metal on the Organization of Tetraamidometallophthalocyanines in Langmuir−Blodgett Films

Metallophthalocyanines (MPc's) [M being one of the following metal ions:  Co(II), Ni(II), Cu(II), or Zn(II)], bearing amide side chains and being highly soluble in organic solvents, have been synthesized by starting from the corresponding phthalonitrile. All four compounds can form Langmuir and Langmuir−Blodgett films, but interestingly, their behavior as monolayers was shown to be very much dependent on the central metal ion. The study of Π−A isotherms, low-angle X-ray diffraction patterns, and IR dichroism allowed us to elucidate these behaviors. Cobalt and zinc phthalocyanines are coordinated with water molecules and therefore orient with an angle of around 60° with the normal to the air−water interface or to the substrate. On the other hand, nickel phthalocyanine is not coordinated with water; Π−Π interactions become possible, and the molecules can orient more vertically at the air−water interface; they form columns that orient in the transfer direction during the deposition process. Finally, the copp...