A series of free base meso-tetraarylporphyrins functionalized with substituents containing one, two, and four cyclooctatetraene (COT) moieties have been obtained characterized by spectral photophysical studies. Three COT-free porphyrins served as reference compounds. COT is a triplet quencher, well-known to enhance the photostability several, but not all, fluorophores. In case porphyrins, subst...