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A water-soluble porphyrin bearing multi-dentate ligands was prepared, and its aggregation behavior in solution under various conditions (temperature, pH, metal ion, chiral compound) was investigated using UV-vis absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy. Upon the addition of Ca 2+ , Ba 2+ , or Sr 2+ to a solution of porphyrin, the porphyrin first forms an H-aggregate and is then transformed to a J-aggregate at 25 °C in buffered aqueous solution (pH 7.4). On the other hand, the porphyrin forms a self-aggregate (H-aggregate) at 25 °C in buffered aqueous solution (pH 6.0), and the H-aggregate does not form the J-aggregate upon the addition of the group II metal ions. The measurement of CD spectra revealed that the H-aggregate that forms right after the addition of Ba 2+ to the porphyrin solution in the presence of D-or L-phenylalanine does not show an induced CD signal, while the J-aggregate formed from the H-aggregate shows induced CD signals in the Soret region.