Synthesis and Structure of a Functionalized [9]Cycloparaphenylene Bearing Three Indeno[2,1-a]fluorene-11,12-dione-2,9-diyl Units.

A synthetic pathway to a functionalized [9]cycloparaphenylene bearing three indeno[2,1-a]fluorene-11,12-dione-2,9-diyl units in the macrocyclic ring structure ([3]CIFO) has been developed. The 1H and 13C NMR spectra show that only the anti rotamer (anti-[3]CIFO) is produced. DFT calculations indicate that the anti rotamer is thermodynamically more stable than the syn rotamer by 4.3 kcal/mol, and the rotational barrier from the anti to syn rotamer is estimated to be 23.3 kcal/mol. The UV-vis and fluorescence spectra and cyclic voltammogram of anti-[3]CIFO were investigated.