EFFECT OF STEARIC-ACID ON MOLECULAR-ORIENTATION IN METAL-FREE 2,9,16,23-TETRA-TERT-BUTYLTETRABENZOTRIAZAPORPHINE LANGMUIR-BLODGETT-FILMS

Langmuir-Blodgett films of 2,9,16,23-tetra-tert-butyltetrabenzotriazaporphine (TBTAPC(15), C-15 refers to a pentadecyl hydrocarbon long chain), codeposited with stearic acid (SteA), were studied. The TBTAPC(15) molecules, forming a monolayer in a pure state, can only assemble themselves on the water surface in an edge-touching fashion. :However, the admixture of stearic acid substantially affects the molecular orientation, as indicated by the consistent;increase :in the area per TBTAPC(15) molecule with increasing stearic acid concentration. The transferability and dichroic behavior of the films with different orientations were investigated. The data are interpreted in terms of the TBTAPC(15) molecules changing their orientation from an essentially vertical pattern to a horizontal pattern when a sufficient amount of stearic acid was present. A cyclic voltammogram of the pure TBTAPC(15) LB film was obtained with an indium-doped SnO2 (ITO) electrode.