Interplay Between Cone and Partial-Cone Geometry in Doubly-Bridged Calix[8]arenes Investigated by X-ray and 2D NMR

X-Ray crystallography proves the occurrence in 1,5:3,7-doubly-bridged calix[8]arenes of a 3/4-cone geometry which can be transformed, in analogy to calix[4]arenes, to an unprecedented 3/4-partial-cone arrangement by proper alkylation of the free OH groups.