Theoretical insights into chirality-controlled SWCNT growth from a cycloparaphenylene template

A self-assembly mechanism for low-temperature SWCNT growth from a [6]cycloparaphenylene ([6]CPP) precursor via ethynyl (C(2)H) radical addition is presented, based on non-equilibrium quantum chemical molecular dynamics (QM/MD) simulations and density functional theory (DFT) calculations. This mechanism, which maintains the (6,6) armchair chirality of a SWCNT fragment throughout the growth process, is energetically more favorable than a previously proposed Diels-Alder-based growth mechanisms [E. H. Fort, et al., J. Mater. Chem. 2011, 21, 1373]. QM/MD simulations and DFT calculations show that C(2)H radicals play dual roles during SWCNT growth, by abstracting hydrogen from the SWCNT fragment and providing the carbon source necessary for growth itself. Simulations demonstrate that chirality-controlled SWCNT growth from macrocyclic hydrocarbon seed molecules with pre-selected edge structure can be accomplished when the reaction conditions are carefully selected for hydrogen abstraction by radical species during the growth process.