AGGREGATION OF 2,3-DIHYDROXY-ETIOCHLORIN-I - AN AMPHIPHILIC MODEL-COMPOUND FOR PHOTODYNAMIC THERAPY AND GREEN HEME-D

The crystal structure of 2,3-dihydroxy-etiochlorin I has been determin ed to obtain information on its aggregation behavior. Cis-dihydroxychl orins serve as model compounds for green heme d and show promising pho tonecrotic activity in photodynamic therapy. The compound shows strong aggregation in the solid state facilitated by intramolecular hydrogen bonding between one hydroxy group and pyrrole nitrogens of neighborin g molecules. This novel type of aggregation leads to chain-type aggreg ates in the crystal. The title compound 4 crystallized in the monoclin ic space group Ia (Z = 4) with unit cell dimensions a = 9.902(4) Angst rom, b = 26.430(9) Angstrom, c = 10.823(5), beta = 104.47(3) Angstrom, V = 2743(2) Angstrom(3). The structure was refined to an R-value of 0 .097 on the basis of 1150 reflections with F > 4.0 delta (F) (130 K).