Synthesis and Luminescence of Soluble meso-Unsubstituted Tetrabenzo- and Tetranaphtho[2,3]porphyrins
journal contributionposted on 11.11.2005, 00:00 by Olga S. Finikova, Andrei V. Cheprakov, Sergei A. Vinogradov
Syntheses of soluble tetrabenzoporphyrins (TBP) and tetranaphtho[2,3]porphyrins (TNP), with multiple substituents in the conjugated aromatic rings but bearing no substituents in the meso-positions, is reported. Both types of porphyrins were obtained by direct aromatization of precursor porphyrins, annealed with either cyclohexene or dihydronaphthalene fragments. TBPs and TNPs possess powerful absorption bands in the near-infrared (λ = 610−710 nm, ε = 100,000−300,000 M-1 cm-1) and exhibit strong luminescence. Free bases and Zn complexes fluoresce with quantum yields of up to 50%, whereas Pd and Pt complexes phosphoresce in solutions at ambient temperatures. Remarkably, the phosphorescence quantum yields of Pd and Pt TBPs reach as high as 20−50%, which places them among the brightest near-infrared phosphors known to date.