Neutral porphyrin J-aggregates in premicellar SDS solution

In aqueous neutral sodium dodecyl sulfate (SDS) solution, as meso-tetra(4-hydroxyphenyl)porphyrin (THPP) monomers insert SDS aggregation, a strong porphyrin-porphyrin interaction is observed, and then the porphyrin J-aggregates form slowly. The concentration of SDS necessary to give the maximum amount of J-aggregates is 5.0 mM. The J-aggregates have been studied by optical absorption, fluorescence, and resonance light scattering spectroscopies. The J-aggregates have two strong exciton bands corresponding to the B-band and Q-bands of THPP monomers. The total fluorescence of THPP is quenched due to the aggregate formation. A strong and sharply peaked resonance light scattering signal (at 490 nm) which suggests a delocalized excitonic state is observed just slightly to the red of the J-aggregates absorption maximum. The J-aggregates are still very steady even if the solutions were stored in the dark for more than a year.