Photochemical generation of 9-Fluorenyl radicals

A series of 9H-fluorenols and 9H, 9’H-bifluorenyls were irradiated in less polar solvents giving photoproducts derived from their corresponding 9H-fluorenyl radicals. These transient species were directly observed by laser flash photolysis and their UV/visible spectra compared to those of their corresponding cations. Theoretical calculations (DFT) of these intermediates indicate their destabilizing nature in similar fashion to the antiaromatic character of the corresponding cations.

Audience take-away:

• The concept of Photochemistry and equipment used,
• The nature of reactive intermediates and how they are useful in understanding mechanisms
• Substituent effects in predicting stabilities of intermediates.