Self-Assembly of Synthetic Bacteriochlorophyll-f Analogues Having C8-Formyl Group

Abstract 31-Epimerically pure C8-formyl analogues Zn–3R/S of zinc methyl bacteriopheophorbide-f (Zn–MBPhe-f) were synthesized. Their spectroscopic and self-aggregation properties were compared to those of Zn–MBPhe-f possessing the C7-formyl group (Zn–2R/S) as a model compound of bacteriochlorophyll-f. Movement of a formyl group from the 7- to 8-position as in Zn–2 → Zn–3 caused large spectral changes in both monomeric and oligomeric forms. Monomeric Zn–3R/S in THF showed a more red-shifted Qy peak (650 nm) than Zn–2R/S (628 nm), but both afforded the same Soret maximum at 448 nm. Self-aggregates of Zn–3R/S in 6% (v/v) THF–H2O gave a more red-shifted Qy peak accompanied by a large diastereomeric control in the oligomeric Qy peaks.