Journal of the American Chemical Society
ABSTRACT: Solid-state topochemical polymerization (SSTP) is a promising method to construct functional crystalline polymeric materials, but in contrast to various reactions that happen in solution, only very limited types of SSTP reactions are reported. Diels−Alder (DA) and dehydro-DA (DDA) reactions are textbook reactions for preparing six-membered rings insolution but are scarcely seen in solid-state synthesis. Here, using multiplecutting-edge techniques, we demonstrate that the solid 1,4-diphenylbuta-diyne (DPB) undergoes a DDA reaction under 10−20 GPa with the phenyl as the dienophile. The crystal structure at the critical pressure shows that this reaction is “distance-selected”. The distance of 3.2 Å between the phenyl and the phenylethynyl facilitate the DDA reaction, while the distances for other DDA and 1,4-addition reactions are too large to allow the bonding. The obtained products are crystalline armchair graphitic nanoribbons, and hence our studies open a new route to construct the crystalline carbonmaterials with atomic-scale control.