BACTERIOCHLOROPHYLL AGGREGATES IN POSITIVELY CHARGED MICELLES

Micellar complexes were prepared from bacteriochlorophyll alpha and ba cteriopheophytin alpha with the cationic detergents, cetyltrimethyl am monium bromide and cetylpyridinium chloride. These complexes have spec troscopic properties (absorption, circular dichroism) which are very d ifferent from the ones formed with non-ionic detergents like Triton X- 100, and also with anionic detergents. Bacteriochlorophyll a forms two complexes: One is blue-shifted and has excitonically coupled Q(y) tra nsitions. The second one is extremely red-shifted. The unusual propert ies are suggested to result from interactions of the positively charge d head-group of the detergent with the tetrapyrrole.