Interlocked structures constructed from cucurbituril

Cucurbituril is a hexameric macrocyclic compound with the formula (C6H6N402)6 shaped like a pumpkin which belongs to the botanical family Cucurbitaceae. This macrocyclic cavitand has idealized symmetry Z 6h with a hydrophobic internal cavity of about 0.55 nm. The two portals, which are each laced by six hydrophilic carbonyl groups, have a diameter of 0.4 nm [Fig. 20.4.8(a)], 

Like a molecular bead, cucurbituril can be threaded with a linear diammonium ion to form an inclusion complex [Fig. 20.4.8(b)]. This is stabilized by the fact that each protonated amino N atom forms hydrogen bonds to three of the 

Hexamethylenetetramine-like structure unit in the diamondoid network of 

The binuclear terbium centers and type I rotaxanes form a two-dimensional layer. Stacked layers are further interconnected via type II rotaxanes to form a three-dimensional polyrotaxane network, which has an inclined a-polonium topology with the binuclear terbium centers behaving as six-connected nodes (Fig. 20.4.10). The void space in the crystal packing is filled by a free rotaxane unit, NOJ and OH- counter ions, and water molecules. 

-bis(4-pyridylmethyl)-l,4-diaminobutane, and its subsequent reactions to yield linear polymers, a puckered layer, and a molecular triangle. 

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