Side Chain Functionalization Using Hydrogen Bonding

Side Chain Functionalization Using Hydrogen Bonding 

The groups of Week (South et al. 2007) and Sleiman (Bazzi et al. 2003 Chen et al. 2005) synthesized a variety of copolymers functionalized by either thymine or 

Side Chain Functionaiization Using Metai Coordination 

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Side Chain Functionalization Using Hydrogen Bonding... 

To explore this issue, Monte Carlo computer simulations were run using the protocol outlined in the previous section. In these simulations, however, a peptide of sequence Ac-Ala-Xaa-Ala-Ala-NMe was employed (Xaa = Gin or Asn), the backbone was not constrained to the PPII conformation, and a side chain-to-backbone hydrogen bond was constrained using a potential function previously used to constrain a-helical backbone-to-backbone hydrogen bonds (Tun and Hermans, 1991 Creamer and Rose, 1994). 

Figure 5.1 Examples of hydrogen bonding motifs used in side chain functionalizations of polymers (a) one-point complementary, (b, c) two-point dimerizing, (d, e) three-point complementary, (f) four-point dimerizing, (g) four-point complementary, and (h) six-point complementary hydrogen bonding motifs.

The previous section described the supramolecular side chain functionalization of polymers based on a single recognition motif. However, biological systems use a wide variety of noncovalent interactions such as hydrogen bonding, metal coordination, and hydrophobic interactions in an orthogonal fashion to introduce function,... 

Figure 5.5 Side chain functionalization of diblock copolymers 1 and 2, using a combination of hydrogen bonding and metal coordination.

Zimmerman and coworkers made use of complementary quadruple hydrogen-bonding complexes to form networks and blend two different side-chain functionalized polymers, poly(butyl methacrylate) (PBMA, marked in light blue) and PS (marked in red. Figure 5). The polymer blends were characterized by differential scanning calorimetry (DSC),... 

Miller and coworkers have shown that short peptides containing N-alkylated histidine residues can be used as catalyst for the enantioselective acylation of secondary and some tertiary alcohols. The N-alkylated histidine residues are postulated to facilitate acylation by a nucleophilic mechanism, whereas the backbone amides and side chain functionalities are supposed to govern the selectivity through enantiomer-specific secondary contacts (hydrogen bonding, 7i-stacking, ion pairing, etc.) [28]. 

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