Microstructure of monolayered aggregate of 5-(4-carboxyphenyl)-10,15,20-triphenylporphine self-assembled at the toluene/water interface

Abstract 5-(4-Carboxyphenyl)-10,15,20-triphenylporphine (TPPCOOH) was acid-dissociated and its salt with alkali metal ions (TPPCOO−M+, M+=Li+, Na+, and K+) formed ordered needlelike monolayered aggregates at the toluene/water interface under alkaline conditions. The light absorption of the aggregates at 451 nm depended on the polarization direction. The dependence revealed 2 types of TPPCOO−M+ aggregates with different growth direction, but their microstructure and interfacial concentration were almost the same. The height of the aggregates measured by atomic force microscopy was approximately equivalent to that of titled TPPCOO−.