The conformational change of the s-cis, s-trans-9, 9′: 9′, 9 ″-terfluorenyl to the s-cis, s-cis form via the radical process was performed by means of a reaction with N-bromosuccinimide and with various oxidizing agents. A reverse change occurred on treatment with lithium aluminum hydride and with sodium bis (2-methoxyethoxy) aluminum hydride.