Synthesis and Studies of Strained Fluorenophyrins

New examples of polyaromatic hydrocarbons embedded porphyrinoids named fluorenophyrins, which are fluorene-embedded porphyrins, have been readily synthesized starting with commercially available fluorene as a key precursor over a sequence of four simple synthetic steps. These new fluorenophyrin macrocycles were characterized and studied by high-resolution mass spectrometry, one-dimensional and two-dimensional nuclear magnetic resonance and absorption spectroscopies, electrochemical techniques, and density functional theory calculations. The studies indicated that the fluorenophyrins are nonaromatic, and π-conjugation in macrocycles was limited due to nonplanar arrangement of a fluorene moiety with the rest of the macrocycle.