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 [DPA8OS] with tetraphenylcyclopentadienone or tetra(p-tolyl)cyclopentadienone to form octa(hexaphenylbenzene)octasilsesquioxane, (Ph6C6)8OS, or octa(tetratolyldiphenylbenzene)octasilsesquioxane, (p-Tolyl4Ph2C6)8OS. Likewise, tetra(p-tolyl)cyclopentadienone reacts with octa(p-tolylethynylphenyl)OS to form octa(pentatolylphenylbenzene)octasilsesquioxane (p-Tolyl5PhC6)8OS. These compounds, with molecular weights of 4685−5245 Da, were isolated and characterized using a variety of analytical methods. The crystal structure of DPA8OS offers a 3 nm3 unit cell with Z = 1. The crystal structure of (Ph6C6)8OS was determined to have a triclinic unit cell of 11 nm3 with Z = 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.