Single Crystal to Single Crystal Polymerization of a Self-Assembled Diacetylene Macrocycle Affords Columnar Polydiacetylenes

This manuscript describes a single-crystal-to-single-crystal polymerization of the dihydrate of diacetylene 1 (1 center dot 2H(2)O) to give an unusual polydiacetylene (PDA) structure that consists of aligned nanotubes, with each covalently bonded nanotube having two parallel PDA chains that run parallel down opposite sides of a channel defined by the macrocycle. Each PDA nanotube is connected with four other columns via amide hydrogen bonds with an N-(H)center dot center dot center dot O distance of 2.888(4) angstrom. Such well-ordered polymers should display quasi-one-dimensional electronic structures and may be of interest for the formation of highly conductive organic materials. We obtained the 1 center dot 2H(2)O form in bulk, which was polymerized by heating. Powder X-ray diffraction suggests that bulk PDA powder is single phase and displays a similar structure as the PDA single crystals. Furthermore, we showed that PDA crystals absorbed I-2 vapor. We believe that this unique PDA structure, which is amenable to property control via adsorbed guests, will be an attractive one for investigating charge-transfer doping in PDA-based organic electronic materials. We also observed two additional crystal forms, including 1 center dot MeOH, which also shows a columnar assembly, and a tetrahydrate 1 center dot 4H(2)O that shows water tetramers that link four cycles into a 2D sheet structure.