A unique calix[4]arene lower-rim intramolecular rearrangement, resulting in molecular asymmetry arising from the upper- and lower-rim substitution pattern, produces a new class of inherently chiral calix[4]arenes in a partial cone conformation. This was aided by molecular rigidification arising from pi-pi and C-H.pi interactions between bulky lower-rim substituents, with the corresponding circular dichroism spectra exhibiting the most intense bisignate Cotton effects yet observed for calix[4]arenes not bearing a chiral center.
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