Fast and Robust Route to Hydroporphyrin-Chalcones with Extended Red or Near-Infrared Absorption

The reaction of an acetylchlorin or diacetylbacteriochlorin with an aldehyde under microwave conditions readily affords the corresponding hydroporphyrin-chalcone. The aldehydes include aryl aldehydes, cinnamaldehyde, and all-trans-retinal. The chalcone causes a bathochromic shift of the long-wavelength absorption band of the hydroporphyrin by up to 24 nm. The facile conjugation and wavelength tunability should make such constructs valuable for fundamental spectroscopic studies as well as diverse photochemical applications in the relatively unexplored red and near-infrared spectral regions.