Abstract Computer deconvolution of the optical absorption spectra has been used to follow the formation and transformation of various chlorophyll species formed by lowering the temperature in solutions of toluene or methylcyclohexane containing a hydrogen-bonding nucleophile such as ethanol. At cryogenic temperatures the self-assembled chlorophyll a-ethanol species has optical properties similar to those of special pair photoreaction center chlorophyll. Analysis of the absorption and fluorescence behavior of the self-assembled species suggests that chlorophyll-chlorophyll species are also formed in the self-assembly process. Fluorescence lifetime measurements indicate that the pathways for dissipation of excitation energy in these multicomponent systems are complex. Selective optical excitation at wavelengths corresponding to absorption of monomer, oligomer, etc. chlorophyll a species has been used to demonstrate the heterogeneous nature of these self-assembled systems.