Excited-state absorption of mono-, di- and tri-nuclear cyclometalated platinum 4,6-diphenyl-2,2′-bipyridyl complexes

The ground-state absorption cross-sections (σg), triplet excited-state absorption cross-section (σT) at 532 nm, singlet excited-state absorption cross-sections (σs) at various visible wavelengths, singlet and triplet excited-state lifetimes, and triplet quantum yields of three cyclometalated platinum(II) 4,6-diphenyl-2,2′-bipyridyl complexes, are reported. The presence of metal–metal and π–π interactions in the dinuclear and trinuclear complexes results in a significant increase in their respective σg’s in the visible spectral region. As a result, the ratio of σs/σg and σT/σg at each wavelength is significantly greater for the mononuclear complex than for the dinuclear and the trinuclear complexes.