| Abstract
| - Zinc 3-hydroxymethyl-13-formyl-chlorin, 1, and its 3,13-inverted (3-formyl-13-hydroxymethyl) regioisomer, 2, and their corresponding 17,18-dehydrogenated porphyrins, 3 and 4, were synthesized for modelsof natural bacteriochlorophylls-c/d/e possessing 31-OH and 13-CO groups which self-aggregate in mainlight-harvesting antenna systems of green photosynthetic bacteria. Zinc chlorins 1 and 2 were monomersin neat THF and gave an obvious difference in their visible absorption spectra, indicating that sole inversionof the 3- and 13-substituents in a chlorin chromophore controlled their optical properties. In an aqueousTriton X-100 solution (a nonionic surfactant), zinc 31-OH-13-CHO-chlorin 1 and porphyrin 3self-aggregated as do natural bacteriochlorophylls, while zinc 3-CHO-131-OH chlorin 2 and porphyrin 4(the 3,13-inverted regioisomers of 1 and 3) hardly formed such large oligomers, showing that the inversionof the peripheral 3,13-substituents made their oligomerization unfavorable. FT-IR spectra of aggregated1−4 in the solid film and their molecular modeling calculations suggested that the 172-CO moiety ininverted 2/4 interacted with its own 131-OH group to disturb further aggregation.
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