Multibridged chiral naphthalene oligomers with continuous extreme-cisoid conformation

Axially chiral 2,2′-methylenedioxy-bridged-1,1′-binaphthyls, quaternaphthalenes, and octinaphthalenes were synthesized and their optical properties researched. 2,2′-Methylenedioxy bridges led to a continuous extremely cisoid conformation and subsequent extensive conjugation in the rod direction. Therefore, the absorption and fluorescence regions were red-shifted as the number of naphthalene rings increased. These oligonaphthalenes fluoresced in both solution and the solid state. Furthermore, DFT calculations showed that the LUMO and HOMO of these bridged oligonaphthalenes were spread over a wide range.