Molecular Balances Based on Aliphatic CH-π and Lone-Pair-π Interactions

CH center dot center dot center dot pi and lone-pair center dot center dot center dot pi interactions are estimated for a series of conformationally dynamic bicyclic N-aryliimides. On the basis of their strengths and mutual synergy/competition, the molecules prefer a folded/unfolded conformation. Calculations suggest strategies to selectively isolate the folded form by increasing the strength of the attractive CH center dot center dot center dot pi interaction or removing the lone-pair center dot center dot center dot pi repulsion. While the barrier for the folded (sic) unfolded transformation is too large to conformationally lock the molecules in either of the conformers, the dynamics for hopping of the alkyl group across rings and tumbling over the rings are found to be facile in the folded conformation.