Ureido-pyrimidinone

Fig. 1 Supramolecular polymer of bifunctional ureido pyrimidinone derivative reported by Lehn...

Fig. 4 Hydrogen-bonded thermoplastic elastomer based on self-complementary interactions of ureido-pyrimidinone (UPy). (a) Poly(ethylene-co-butylene) with OH end groups, (b) Poly(ethyl-ene-co-butylene) functionalized with UPy. (c, d) Lateral intraactions through tt—tt stacking of UPy and hydrogen bonding of urethane linkers, (e) AFM image of nanofibers formed through these lateral interactions. Reprinted with permission friun [90-92]. Copyright 2000, 2006, 2008 Wiley-VCH Verlag GmbH, Wiley Periodieals, Ine., and American Chemical Society...

Figure 34.1 Ureido-pyrimidinone (UPy) unit that forms a self-complementary dimer, and supramolecular polymer formed by a bifunctional UPy derivative. (Image adapted from Ref. [5] 1998, American Chemical Society.)...

Figure 34.5 Supramolecular polymers from hydrogen-bonding r 2-ureido-pyrimidinone (UPy) motif by Meijer et al. (Reprinted wil (b) Supramolecular block copolymer based on the ureido-guano permission from Ref. [15] 2006, American Chemical Society) acid motif as reported by Lehn et al. (Reprinted with permissiot...

The diarylethene (95) with a histamine substituent exhibited the morphology of self-assembled supramolecular architecture which could be tuned from nanofiber to nanosphere upon UV/Vis irradiation. The quadruply hydrogen-bonding ureido-pyrimidinone (96) unit organized by dithienylethene afforded linear assemblies in solutions and underwent... 

Because of its relative ease of synthesis from inexpensive starting materials, the ureido pyrimidinone (UPy) supramolecular motif has been widely exploited in recent years (Figure la). Appending UPy residues at the terminal positions of telechelic polymers such as end-functional polysiloxanes and polyethylene-co-butylene (pE-co-B), transforms previously free flowing, liquid starting materials into tough, elastomeric solids (Scheme 1). 

Schnell, I., Langer, B., Sdntjens, S.H.M. et al. (2002) (Juadruple hydrogen bonds of ureido-pyrimidinone moieties investigated in the solid state by IH double-quantum MAS NMR-spectroscopy. Physical Chemistry Chemical Physics, 4,3750-3758. 

Hydrogen bonds provide probably the most important secondary interactions exploited in natural and supramolecular systems. In fact, using bifunctional monomers with two ureido-pyrimidinone moieties inspired by nucleic acids linear supramolecular polymers held together by quadmple hydrogen bonds have been synthesized. These systems are sometimes called smart materials, as the hydrogen bonds can reversibly rearrange at elevated temperatures, which... 

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.

Sbntjens SHM, Sijbesma RP, van Gendeten MHP, Meijer EW. Stability and lifetime of quad-ruply hydrogen bonded 2-ureido-4[lH]-pyrimidinone dimers. J Am Chem Soc 2000 122 7487-7493. 

The relative insensitivity of this class of Ni catalysts to polar functional groups, and especially their low oxophilicity, is another important characteristic. This property has been exploited for the development of novel polymeric materials that might find new applications. For example, 1-hexene has been copolymerized with 6-(2-ureido-4-[lH]-pyrimidinone)hex-l-ene (30) to generate a new poly(olefin) elastomer (equation 7). The dimerization (through H-bonding) of the pyrimidinone moieties forms noncovalent crosslinks that bestow unique properties to the otherwise amorphous poly(l-hexene) matrix. 

Bis-2-ureido-4[lF/]-pyrimidinones are capable of self-associating into a duplex structure stabilized by eight H-bonding interactions with 70 that are adaptive through a keto—enol tautomerization (Figure... 

Figure 1.4 Synthesis of a monofunctional 2-ureido-4[lH]-pyrimidinone (UPy) (1) and dimerization of 1 in solution forming a quadrupole hydrogen-bonded unit. (After Sijbesma et al., 1997.)...

Supramolecular polymers [2, 133] (also called reversible polymers) are comprised of bifunctimial monomeric units that are reversibly aggregated through relatively strong non-covalent interactions. For instance, the self-complementary and recognition of the quadruple H-bonded bis(2-ureido-4[l//]-pyrimidinone) (bisUPy) can... 

Synthesis of 2-ureido-4[lH]-pyrimidinone methyl methacrylate (UPyMA) monomer and poly(methyl methacrylate-co-2-ureido-4[lH]-pyrimidinone methyl methacrylate (P(MMA-co-UPyMA) copolymers. 

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