SELF-AGGREGATION OF SYNTHETIC ZINC CHLORINS WITH A CHIRAL 1-HYDROXYETHYL GROUP AS A MODEL FOR IN-VIVO EPIMERIC BACTERIOCHLOROPHYLL-C AND BACTERIOCHLOROPHYLL-D AGGREGATES

3(1)-Epimerically pure zinc 3-(1-hydroxyethyl)-13(1)-oxochlorins posse ssing several substituents at the 20-position were prepared. In non-po lar organic solvents, the synthetic zinc complexes self-aggregated to form oligomers with >700-nm absorption and giant CD peaks, which were dependent upon the 3(1)-absolute configuration as well as the 20-subst ituents. The in vitro self-aggregates of hch epimeric zinc chlorin wit h a 20-methyl group showed similar visible and CD spectra with the in vivo bacteriochlorophyll-c (3(1)RIS=2/1) aggregates in extramembranous antennae of a green photosynthetic bacterium. The spontaneous in vitr o self-aggregates of 3(1)RIS(=2/1)-epimeric mixture of the zinc 20-met hylchlorins were different from the natural supramolecules, indicating that in vivo slow oligomerization of 3(1)RIS(=2/1)-bacteriochlorophyl ls-c induced the regular supramolecular structures and/or the epimeric ally separated assemblies. (C) 1998 Elsevier Science Ltd. All rights r eserved.