Novel spiro-fluorenes from tandem radical addition for liquid crystalline monodisperse conjugated oligomers

3'-Nonafluorobutylmethyl-4'-methyl-spiro[cyclopentyl-9,1']fluorenes were successfully synthesized via tandem radical-addition reactions between 9,9-diallylfluorenes and perfluorobutyl iodide in the presence of a radical initiator followed by reduction under mild conditions. Single crystal analysis indicates that two substituents at 3,4-positions of cyclopentane are in a maleinoid form. Accordingly, four oligo(fluorene-co-bithiophene)s with the same molecular length of similar to 10 nm (7 fluorene units and 12 thiophene units) containing one to three novel spiro-fluorene units were synthesized.