Hydrogen bond interactions acceptor group

Structural refinement of these host molecules was later pursued by the same group on a double track. In the non-covalent direction, studies were finalized to the design of calix[5]arene pentols fitted, at the wider rim, with a molecular hook capable of facilitating Cgo and C o capsule formation via additional self-assembling interactions between the two sub-units. To this end, ureido 2a [11] and 2,2 -bipyridyl (bpy) derivative 2b [12] were endowed with a self-complementary hydrogen-bond donor/acceptor group and a metal-acceptor (Ag binding site, respectively. 

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