Polyyne [3]rotaxanes: Synthesis via dicobalt carbonyl complexes and enhanced stability.

New strategies for synthesizing polyyne polyrotaxanes are being developed as an approach to stable carbyne 'insulated molecular wires'. Here we report an active metal template route to polyyne [3]rotaxanes, using dicobalt carbonyl masked alkyne equivalents. We synthesized two [3]rotaxanes, both with the same C28  polyyne dumbbell component, one with a phenanthroline-based macrocycle and one using a 2,6-pyridyl cycloparaphenylene nanohoop. The thermal stabilities of the two rotaxanes were compared with that of the naked polyyne dumbbell in decalin at 80 °C, and the nanohoop rotaxane was found to be 4.5 times more stable.