Topochemical strategies and experimental results for the rational synthesis of carbon nanotubes of one specified type

A generic topochemical route for the rational synthesis of carbon single walled nanotubes (SWNTs) of one specified type is proposed and analyzed using theoretical and experimental results. This route uses crystal-controlled 1,4-addition polymerization of diacetylene groups in cyclic monomer molecules to make organic nanotubes, whose three-dimensional covalent network combines carbon-carbon bonds of the cyclic monomer and four parallel polydiacetylene chains formed by solid-state reaction. Up to 75% of the carbon-carbon bonds of the target carbon nanotube are correctly connected in the organic nanotube, and none are incorrectly connected. Target monomers are down selected by using molecular mechanics calculations to predict the allowable crystal packing parameters, from which topochemical reactivity is predicted using a well-established reactivity diagram. This approach correctly predicts the solid-state polymerizability of a cyclic diacetylene that we experimentally demonstrated forms a targeted hydrocarbon nanotube. Substituent extrusion is the final step in forming the carbon nanotube from the organic nanotube, which should occur cleanly because the covalent connectivity of the organic nanotube holds the structure in place. Using this two-step topochemical control of reaction and structure, during formation of the organic nanotube and during substituent extrusion, routes to armchair and zigzag SWNTs having different ring diameters are proposed. (C) 2003 Elsevier B.V All rights reserved.