Remarkable homology in the electronic spectra of the mixed-valence cation and anion radicals of a conjugated bis(porphyrinyl)butadiyne.

The pi-radical cation and anion of the dizinc complex of a bis(triarylporphyrinyl)butadiyne, 1+ and 1-, respectively, display remarkably similar near-IR signatures, with intense bands near 1000 and 2500 nm, as predicted by the appropriate frontier-orbital model for inter-porphyrin coupling across the conjugated bridge.