Polymers multiple hydrogen bonds

A solution leading to a successful algorithm was recently found for the folding of ribonucleic acid (RNA) [36], Natural RNA polymers (figure C2.14.1) are mainly made up from four different bases . A, C, G and U. As with DNA, multiple hydrogen bonding favours the fonnation of G-C and A-U pairs [16, 37, 38] which leads to the appearance of certain characteristic stmctures. Loop closure is considered to be the most important folding event. 

Addition of 81-SH to 80-SS-81 led to formation of the homodisulfide compounds and an equilibrium, with an exchange constant of 1.8, was established. The presence of the templating (D)Pro(L)Val(D)Val tri-peptide in this mixture, shifted the equilibrium dramatically and the formation of the homodisulfide 80-SS-80 was amplified with a Keq=32. Since the templating tri-peptide was supported on polymer beads, the isolation of receptor 80-SS-80 (in 97% purity) was achieved easily by extraction of the beads. The formation of multiple hydrogen bonds between the template and the components of the DCL, led to the isolation of the best possible receptor available from the building blocks present in the equilibrated mixture. 

The concept of supramolecular polymers containing multiple hydrogen bonding units was introduced over a decade ago by Jean-Marie Lehn (Lehn 1993). In this smdy, three-point hydrogen bonding between bifunctional diamidopyridine and thymine... 

Elkins C, Viswanathan K, Long TE. Synthesis and characterization of star-shaped poly(ethylene-co-propylene) polymers bearing terminal self-complementary multiple hydrogen-bonding sites. Macromolecules 2006 39 3132-3139. 

Kugimiya A, Mukawa T, Takeuchi T. Synthesis of 5-fluorouracil-imprinted polymers with multiple hydrogen bonding interactions. Analyst 2001 126 772-774. 

Viswanathan K, Ozhalici H, Elkins CL, Heisey C, Ward TC, Long TE. Multiple hydrogen bonding for reversible polymer surface adhesion. Langmuir 2006 22 1099-1105. 

Multiple Hydrogen Bonding Interactions Self-Sorting on Polymers... 

Week group also investigated the incorporation of multiple hydrogen bonding interactions along a single polymer backbone for both random and block copolymers. 

Kubo H, Nariai H, Takeuchi T. Multiple hydrogen bonding-based fluorescent imprinted polymers for cyclobarbital prepared with 2,6-bis(acrylamido)pyridine. Chem Commun 2003 2792-2793. 

There have been few studies of polymer interconnections within the primary wall of monocots. An arabinoxylan from the primary wall of cultured, barley-aleurone cells,61 and a glucuronoarabinoxylan from maize-coleoptile primary-wall,200 have been shown to bind reversibly to cellulose in vitro, Because xylans are, quantitatively, the major component of monocot primary cell-walls, this interconnection is an important finding it is very likely to occur through multiple hydrogen-bonds, analogous to the interconnection between xyloglucan and cellulose in dicot cell-walls.56,57,59 It is also possible that heteroxylans participate in binding other cell-wall polymers to cellulose. 

Polymers Connected with Multiple Hydrogen Bonds... 

Fig. 46 Combination of two immiscible polymers (PS and PEG) via multiple hydrogen bonds...

The number of supramolecular polymers based on very strong multiple hydrogen-bonded units is relatively small because of the increased synthetic efforts required for the synthesis of the monomers. Intriguing architectures such as nanotubes88 are obtained... 

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