New architectures arising from complementary quadruple hydrogen bonding motifs

There has been a growing interest in the field of supramol. chem. based on self-complementary multiple hydrogen-bonding motifs. Much of the chem. has centered around ureido-pyrimidinone (UPy) due to its relatively straight-forward synthesis and very high assocn. const., Kassoc, on the order of 107 to 108 M-1. Self-assembly of new architectures and materials with directionality, however, is limited with the UPy functionality alone, and requires complementary hydrogen binding motifs. Fortunately, bis-amido-naphthyridines (Napy) have demonstrated selective hetero-complexation with UPy moieties with dimerization consts., Kdim, ranging from 105 to 106 M-1. This work describes recent advances in the synthesis and supramol. chem. of several multi-functional mols. contg. both UPy and Napy groups. Coupling of the highly functional, UPy and Napy supramol. synthons is facilitated by the robust second-generation Grubbs ruthenium olefin metathesis catalyst. These bi-functional mols. enable the self-assembly of a variety of materials such as macrocycles and alternating co-polymers, as well as hyperbranched and star-shaped structures, all of which are highly concn. dependent.