Abstract
A temperature dependent conformational change in the aliphatic chain of 3,6-diketo[8]naphthalenophane is observed by variable temperature nuclear magnetic resonance spectroscopy; the energy of activation for the process is 9.4±0.2 Kcal/mole. For 3,6-diketo[8](2,5)furanophane the conformational change of the chain is more facile than that of the ring with a conservative upper limit for ring rotation of about 9.1 Kcal/mole.