Quadruple Hydrogen Bonding

2-Ureido-l,8-naphthyridine derivatives generate another kind of self-complementary AADD hydrogen bonding motifs (HB-195) [88]. However, the is quite low, which may be attributed to the competition of the strong intramolecular hydrogen bonding (HB-195 ). 

Several DDAD-AADA binding motifs are also available [93,94]. HB-204 and HB-205 are two examples. In this kind of binding motifs, two attractive and four repulsive secondary interactions are genaated. Because the urea monomers can also from strong intramolecular hydrogen bonding (HB-206), these motifs have a mixlerate stability. 

It is also reported that aromatic amide oligomers can also afford stable homodimers that are stabilized by multiple intermolecular hydrogen bonds. HB-222 and HB-223 are two representative examples [101, 102]. In contrast, shorter analogues only form dimers with low stability. It is also revealed that the stacking of the aromatic rings also contributes to the dimerization. 

Acknowledgments We thank The Ministry of Science and Technology and Ministry of Education of China, The Science and Technology Commission of Shanghai Municipality, and The National Natural Science Foundation of China for financial suppoit. 

Pauling L (1939) The nature of the ehemical bond. Cornell University Press, Ithaca 

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J. H. K. K. Hirschbeig, F. H. Beijer, H. A. van Aert, P. C. M. M. Magusin, R. P. Sijbesma, E. W. Meijer, Supramolecular polymers from linear telechelic siloxanes with quadruple hydrogen bonded units , Macromolecules 1999, 32, 2696-2705. 

Hofmeier H, El-ghayoury A, Schenning APH, Schubert US (2004) New supramolecular polymers containing both terpyiidine metal complexes and quadruple hydrogen bonding units. Chem Commun 318-319... 

Sijbesma RP, Beijer FH, Brunsveld L, Folmer BJB, Hirschberg JHKK, Lange RFM, Lowe JKL, Meijer EW. Reversible polymers formed from self-complementary monomers using quadruple hydrogen bonding. Science 1997 278 1601-1604. 

Figure 3.1 Quadruple hydrogen-bonded 2-ureido-4-pyrimidinone units attached to the ends of a polydimethylsiloxane chain assemble to create materials with viscoelastic properties.

Scherman OA, Ligthart GBWL, Ohkawa H, Sijbesma RP, Meijer EW. Olefin metathesis and quadruple hydrogen bonding a powerful combination in multistep supramolecular synthesis. Proc Natl Acad Sci USA 2006 103 11850-11855. 

Beijer FH, Kooijman H, Spek AL, Sijbesma RP, Meijer EW. Self-complementarity achieved through quadruple hydrogen bonding. Angew Chem Int Ed 1998 37 75-78. 

Polymers Connected with Quadruple Hydrogen Bonds... 

Fig. 27 Quadruple hydrogen bonds with binding constants of 6 x 10 M left) and 2 X 10 right)...

Fig.31 Self association of a oligo(p-phenylenevinylenes) and perylenes as well as b olig(p-phenylenevinylenes) via quadruple hydrogen bonds...

The quadruple hydrogen bonding motif of UPy (Fig. 2a) has been designed to form very strong dimers (K im = 2 x 10 L mol in chloroform at 25 °C) [23-25]. Consequently, difunctional monomer 1 (Fig. 2b) forms long chains even in dilute solutions from the value of the equilibrium constant, a degree... 

Fig. 4 Supramolecular polymers due to quadruple hydrogen bonding between bifunctional ureidopyrimidinone derivatives [74]... 

There has been much interest, particularly in recent years, in the design and construction of molecules that self-assemble via quadruple hydrogen bonding.14 19 Such bonding may be used to construct molecular assemblies of high stability. In... 

Gong has recently described a class of oligoamides that employ quadruple hydrogen bonding to form solid-state homodimers (Fig. 7).18 The monomers were derived from 3-aminobenzoic acid, 1,3-benzenedicarboxylic acid, and 1,3-diamino-benzene and, similar to Meijer s group, formed via DADA and DDAA sequences. In contrast to Meijer and colleagues, however, the donor and acceptor units were separated within the monomers such that secondary interactions were less prevalent... 

Figure 4. Hydrogen-bonding unit 7 that dimerizes via quadruple hydrogen bonding without regard to tautomeric form.

Figure 27. (a) Monofunctional ureidotriazines 49 and 51 and the mode of association of 49 via quadruple hydrogen bonding in a disk and stacking of the disks in columns lacking positional order (b) bifunctional ureidotriazines 50 and 52 and the helical columns formed by these molecules in which the disks are positionally ordered. 

Purines, pyrimidines, triazines as components of quadruple hydrogen-bonded systems 03CC5. 

It is clear that cocrystallization of 2 with pyridine and its derivatives in the presence of a suitable guest results in the extension of the cavity of 2 in which four pyridine units assemble along the upper rim of 2, as two stacked dimers, to yield a multicomponent complex 4 in which 2 serves as a quadruple hydrogen bond donor. During studies aimed at cocrystallizing 2 with pyridines from aromatic... 

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