Hydrogen multipoint

Figure 6.7 Illustration of multipoint hydrogen bonding based self-assembly (a) hydrogen bond formation between barbituric acid functionalized gold nanoparticles and Hamilton receptor functionalized block copolymers and (b) selective deposition of nanoparticles on a microphase-separated block copolymer film. Reprinted with permission fi om Binder et al. (2005). Copyright 2005 American Chemical Society.

Scheme 14 Presumptive multipoint hydrogen bonding between Ur6IN and DAP systems.

Several thermodynamic and kinetic behaviors of enzyme-catalyzed reactions performed in ILs, with respect to enzymatic reactions carried out in conventional solvents, could lead to an improvement in the process performance [34—37]. ILs showed an over-stabilization effect on biocatalysts [38] on the basis of the double role played by these neoteric solvents ILs could provide an adequate microenvironment for the catalytic action of the enzyme (mass transfer phenomena and active catalytic conformation) and if they act as a solvent, ILs may be regarded as liquid immobilization supports, since multipoint enzyme-1L interactions (hydrogen. Van der Waals, ionic, etc.) may occur, resulting in a flexible supramolecular not able to maintain the active protein conformation [39]. Their polar and non-coordinating properties hold considerable potential for enantioselective reactions since profound effects on reactivities and selectivities are expected [40]. In recent years attention has been focused on the appUcation of ILs as reaction media for enantioselective processes [41—43]. 

Moreland concluded with respect to the relationship between the structure and the action of Hill reaction inhibiting herbicides that they establish multipoint attachment with the active centre of chloroplasts by means of hydrogen bonds, thus... 

Protein Binding—Tannins, as the name implies, characteristically form complexes with proteins based on multipoint hydrogen bonding, and this feature can be used to detect and remove tannins from crude extracts. A visible protein-tannin precipitate should be formed on addition of the tannin-containing extract to a relatively concentrated (approx 5%) solution of bovine serum albumin (BSA). The amount of BSA either remaining in solution or in the precipitate can be analyzed by various protein determination assays. 

Adsorbent Binding—In the same way that tannins bind to proteins through multipoint hydrogen bonding, so do they also bind to a number of other polymeric materials. These include the adsorbents commonly used to remove tannins... 

---