Synthesis and characterization of β-fused porphyrin-BODIPY® dyads

Novel dyads in which a porphyrin ring is directly fused through two β-pyrrolic carbons to a BODIPY® moiety have been prepared using a stepwise approach starting from the copper(II) complex of pyrrolo[2,3-c]-5,10,15,20-tetraphenylporphyrin. Formylation and reaction with 3,5-dimethylpyrrole afforded ; subsequent BF2 complexation gave the TPP-BODIPY® dyad in reasonable yields. Demetalation in TFA/H2SO4 led to the corresponding free base , opening the way to the subsequent preparation of the Zn complex . Both and exhibited complex optical spectra with an intensely red-shifted Q-band. Luminescence spectra displayed a very intense band around 700 nm making these species suitable as near-IR dyes and sensors in biological media. Optical analyses of , using the INDO/SCI technique, were performed to obtain information to establish the origin of the novel optical properties. These studies showed that the optical properties of cannot be attributed to deformation of the molecular skeleton, but derive from the increased extension of the conjugation between the TPP and BODIPY® π-systems.