Crystalline Hybrid Polyphenylene Macromolecules from Octaalkynylsilsesquioxanes, Crystal Structures, and a Potential Route to 3-D Graphenes

We report here the Diels−Alder reaction of octa(diphenylacetylene)silsesquioxane [DPA<sub>8</sub>OS] with tetraphenylcyclopentadienone or tetra(<i>p</i>-tolyl)cyclopentadienone to form octa(hexaphenylbenzene)octasilsesquioxane, (Ph<sub>6</sub>C<sub>6</sub>)<sub>8</sub>OS, or octa(tetratolyldiphenylbenzene)octasilsesquioxane, (<i>p</i>-Tolyl<sub>4</sub>Ph<sub>2</sub>C<sub>6</sub>)<sub>8</sub>OS. Likewise, tetra(<i>p</i>-tolyl)cyclopentadienone reacts with octa(<i>p</i>-tolylethynylphenyl)OS to form octa(pentatolylphenylbenzene)octasilsesquioxane (<i>p</i>-Tolyl<sub>5</sub>PhC<sub>6</sub>)<sub>8</sub>OS. These compounds, with molecular weights of 4685−5245 Da, were isolated and characterized using a variety of analytical methods. The crystal structure of DPA<sub>8</sub>OS offers a 3 nm<sup>3</sup> unit cell with <i>Z</i> = 1. The crystal structure of (Ph<sub>6</sub>C<sub>6</sub>)<sub>8</sub>OS was determined to have a triclinic unit cell of 11 nm<sup>3</sup> with <i>Z</i> = 1. The latter structure is believed to be the largest discrete molecular structure reported with 330 carbons. Efforts to dehydrogenatively cyclize (Scholl reaction) the hexaarylbenzene groups to form 3-D octgraphene compounds are described.