Coplanar Oligo(<i>p</i>-phenylenedisilenylene)s Based on the Octaethyl-Substituted <i>s</i>-Hydrindacenyl Groups

The silicon analogues of the oligo(p-phenylenevinylene)s (Si-OPVs) with highly planar structures have been synthesized using a newly developed ligand, the 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) group. Their X-ray crystal structures and spectroscopic data demonstrate that the π-conjugation effectively extends over the Si-OPV framework. Notably, tetrasiladistyrylbenzene exhibits an orange fluorescence even at room temperature both in solution and in the solid state, which is attributable to the effective extension of conjugation. To the best of our knowledge, the tetrasiladistyrylbenzene is the first emissive SiSi derivative even at room temperature.