Quadruple hydrogen bonding units

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... 

Figure 3 Schematic representation of two common supramolecular motifs used in supramolecular polymerizations (a) UPy quadruple hydrogen bonding unit 1, its dimerization, tautomerization, and subsequent complexation with NaPy 2 (b) terpyridine 3 and 2 1 complexation with a low-oxidation-state metal ion M. As shown, each motif demonstrates a different binding mode.

Meijer et al. [64] described an unusual strategy to obtain metastable supramolecular polymer nanoparticles. Each nanoparticle arose from the collapse of a single polymer chain. This approach relied on a PNBE chain functionalized with a photoactivable quadruple hydrogen-bonding unit, which is able to create intramolecular cross-linking of single chains after deprotection. 

Related napthalene bisimides have been attached to a self-complementary quadruple hydrogen-bonding unit, that is a 2-ureido-4[lff]-pyrimidinone (UPy), yielding hydrogen-bonded dimers (18, Fig. 13) [45]. Selective forma-... 

Hirschberg, J.H.K.K., Beijer, F.H., van Aert, H.A. et al. (1999) Supramolecular polymers ftom linear telecheUc siloxanes with quadruple-hydrogen-bonded units. Macromolecules, 32,2696-2705. 

Itee, K.J., Kim, Y.W., Koh, J.H., and Kim, J.H. (2(X)7a) Supramolecular polymer/metal salt complexes containing quadruple hydrogen-bonding units. Journal of Polymer Science Part B-Polymer Physics, 45,3181-3188. 

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.

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.

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... 

Qu, S., Li, F., Wang, H., Bai, B., Xu, C., Zhao, L., et al, 2007. Twin-tapered molecules containing bi-dihydrazine units self-assembly through intermolecular quadruple hydrogen bonding and liquid crystalline behavior. Chem. Mater. 19, 4839—4846. 

ADMET has been used to prepare ABA triblock copolymers in conjunction with living polymerization of a-amino acid-Af-carboxyanhydrides [71]. ADMET was also used in conjunction with ATRP and chck chemistry to synthesize an amphiphilic ABCBA-type block copolymer [72]. Supramolecular graft copolymers based on 2,7-diamido- 1,8-naphthyridines have been synthesized as well [73]. These materials contained a quadruple hydrogen-bond motif in the main chain, from which a complementary hydrogen-bonding unit could be reversibly grafted. 

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