BACTERIOCHLOROPHYLL AGGREGATES IN POSITIVELY CHARGED MICELLES

Micellar complexes were prepared from bacteriochlorophyll alpha and bacteriopheophytin alpha with the cationic detergents, cetyltrimethyl ammonium bromide and cetylpyridinium chloride. These complexes have spectroscopic properties (absorption, circular dichroism) which are very different 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) transitions. The second one is extremely red-shifted. The unusual properties are suggested to result from interactions of the positively charged head-group of the detergent with the tetrapyrrole.