Synthesis, structure and properties of polysubstituted benzo[g]chrysene by FeCl3-promoted from diphenylacetypene and phenylacetaldehyde derivatives

A new and straightforward method has been developed to synthesize polysubstituted benzo[g]chrysene (BgCh) according to controlling the exact stoichiometry of FeCl3 from diphenylacetypene and phenylacetaldehyde derivatives under mild conditions. The BgCh derivatives can also be functionalized by halogenation with Cl, Br and I on the newly built aromatic ring. All the compounds have been fully characterized as well as their photophysical properties, and some of them demonstrated extraordinary liquid crystallinity. The compounds 4e, 4h, 5e and 5h exhibited hexagonal columnar mesophases (Col(h)). In particular, 5h showed a rectangular columnar plastic phase (Col(rp)) under 35 degrees C on cooling. The fluorescence spectra of BgCh revealed a strong emission peak at 405 nm and a shoulder peak near 424 nm in DCM in the range of blue light.