ORGN 240

A new route to substituted meso-tetraaryltetranaphthaloporphyrins (Ar₄TNP) and meso-tetraaryl-octamethoxy-tetranaphthaloporphyrins (Ar₄(MeO)₈TNP) is described. The route includes synthesis of the precursor octahydronaphthalene- or tetrahydronapthalene-fused porphyrins, followed by oxidative aromatization into the target Ar₄TNPs. The precursor porphyrins are produced via the sequences of standard reactions, which include modified Barton-Zard pyrrole synthesis and Lindsey condensation. Ar₄(MeO)₈TNPs exhibit more red-shifted absorption bands than Ar₄TNPs and differ dramatically in solubility. An X-ray structure of PdAr₄TNP (Ar=4-MeO₂C-C₆H₄) revealed that the degree of non-planar distortion in this macrocycle is only slightly higher than that of the homologous tetraaryltetrabenzoporphyrin (Ar₄TBP), suggesting that it is the extra p-conjugation that is responsible for the red shift of Ar₄TNP absorption. Zn and Pd complexes of Ar₄TNPs exhibit strong luminescence at room temperature, suggesting applications in PDT, optical limiting and in vivo oxygen sensing.