Synthesis, structures and properties of benzoporphycenes and naphthoporphycenes

A series of benzoporphycenes and naphthoporphycenes and their zinc complexes were prepared from bicyclo[2.2.2]octadiene fused porphycenes by a retro-Diels-Alder reaction and their photophysical properties were studied. Free-base tetranaphthoporphycene was not soluble in common organic solvents, but zinc tetranaphthoporphycene was slightly soluble in pyridine and showed B- and Q-bands at 507 and 690 nm, respectively. Dinaphthoporphycene showed broad B- and Q-bands due to its lower symmetry. Tetrabenzo-, dibenzo-, and dinaphthoporphycenes showed fluorescence at 673, 654, and 670 nm with quantum yields of 0.32, 0.42, and 0.31, respectively, although their precursors were non-fluorescent. Zinc complexes of tetrabenzo-, dibenzo-, tetranaphtho-, dinaphthoporphycenes and their bicyclo[2.2.2]octadiene-fused precursors revealed moderate fluorescence with quantum yields of 0.15-0.37. The crystal structures of tetrabenzo- and dibenzoporphycenes showed herringbone structures, while the zinc tetrabenzoporphycene showed a hexagonal box-structure with six pyridine ligands inside.
journal article