Charge-transfer heptamethine dyes for NIR singlet oxygen generation.

A heptamethine-based charge-transfer dye was designed based on previous evidence of triplet state formation in orthogonal charge-transfer partners and calculations suggesting the formation of a charge-transfer state in heptamethine dye derivatives. An acridinium derivative of IR-1061 was subsequently synthesized and characterized, demonstrating photochemical reactivity at wavelengths over 1000 nm.