Short-Wavelength Absorbing Complexes of Chlorophyll a in Micellar Solution of Cationic Detergents

Micellar aggregates have been prepared from chloro­ phyll a. Whereas most detergents including non-ionic, zwitterionic and anionic ones, produce aggregates with long-wavelength shifted and enhanced Q Y absorption, the cationic detergents hexadecyl-trimethylammoniumbromide and hexadecyl-pyridiniumchloride produce complexes with opposite traits: The Q Y absorption is shifted to shorter wavelengths, and it is hypochromic. The optical activity is increased as in the long-wave­ length shifted complexes, but the cd bands are non-con­ servative and coincide with the absorption maxima. The complexes are most likely small aggregates of chloro­ phyll with a changed geometry as compared to the “standard” ones.