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-butyltetrabenzotriazap orphine (TBTAPC(15), C-15 refers to a pentadecyl hydrocarbon long chai n), codeposited with stearic acid (SteA), were studied. The TBTAPC(15) molecules, forming a monolayer in a pure state, can only assemble the mselves on the water surface in an edge-touching fashion. :However, th e admixture of stearic acid substantially affects the molecular orient ation, as indicated by the consistent;increase :in the area per TBTAPC (15) molecule with increasing stearic acid concentration. The transfer ability 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 pa ttern 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.