Cooperative hydrogen bond

Vicente, V. Martin, J. Jimenez-Barbero, J. Chiara, J. L. Vicent, C., Hydrogenbonding cooperativity Using an intramolecular hydrogen bond to design a carbohydrate derivative with a cooperative hydrogen-bond donor centre. Chem. Eur. J. 2004,10, 4240-4251. 

As a third example for an organocatalytic reaction, based on multiple hydrogen bonding and mechanistically investigated by DFT, we selected olefin epoxidation with hydrogen peroxide in fluorinated alcohol solvents, such as 1,1,1,3,3,3-hex-afluoro-2-propanol (HFIP) (Scheme 8). Here we encounter a new type of catalytic hydrogen bond the cooperative hydrogen bond. 

Reaction of Danishefsky s Diene with Benzaldehyde Another Example for Catalysis by Cooperative Hydrogen Bonding... 

Kriz J, Dybal J, Brus J. Cooperative hydrogen bonds of macromolecules. 2. Two-dimensional cooperativity in the binding of poly(4-vinylpyridine) to poly(4-vinylphenol). J Phys Chem B 2006 110 18338-18346. 

Hilger C, Stadler R. New multiphase architecture from statistical copolymers by cooperative hydrogen bond formation. Macromolecules 1990 23 2095-2097. 

The thermodynamics of the complexation of a typical polymer pair consisting of proton-donating polyacid and proton-accepting poly(ethylene oxide) (PEO) has been studied since the late 1970s [9,10]. For complexes formed by cooperative hydrogen bonding between a pair of polyacid and polybase with stoichio-... 

Steiner, Th. and Saenger, W. (1992). Covalent bond lengthening in hydroxyl groups involved in three-center and in cooperative hydrogen bonds. Analysis of low-temperature neutron diffraction data. J. Amer. Chem. Soc. 114, 7123-6. 

A highly enantioselective direct Mannich reaction of simple /V-Boc-aryl and alkyl- imines with malonates and /1-kclo esters has been reported.27 Catalysed by cinchona alkaloids with a pendant urea moiety, bifunctional catalysis is achieved, with the urea providing cooperative hydrogen bonding, and the alkaloid giving chiral induction. With yields and ees up to 99% in dichloromethane (DCM) solvent, the mild air- and moisture-tolerant method opens up a convenient route to jV-Boc-amino acids. 

Welhouse, G. J., and Bleam, W. F. (1993b). Cooperative hydrogen bonding of atrazine. Environ. Sci. Technol. 27, 500-505. 

The lastest development is the completely reversible formation of the nanostructures comprising 8 different rosette layers (27 different components) that are held together by 144 cooperative hydrogen bonds. Regarding their size (—5.5 x 3.1 x 2.7 nm) and their molecular weight ( 20 kDa), these nanostructures are comparable to small proteins (Figure 4.4).14... 

Figure 3. Views perpendicular to the faces of the ice (lh) crystal showing the next layer attached (with O-atoms black), (a) Basal face where only isolated water molecules attach, (b) Prism face, where pairs of newly-attached water molecules may hydrogen bond to each other one hydrogen bond/two water molecules. The distance between equivalent water molecules are 0.452 nm (marked ) and 0.738 nm (marked ). (c) 11-20 face, where chains of newly-attached water molecules may cooperatively hydrogen bond to each other one hydrogen bond/water molecule. These form ridges which divide and encourage conversion into two prism faces.

Table 2.9. Cooperative hydrogen-bond configurations observed in crystal structures Finite or infinite chains in carbohydrates and some hydrated nucleosides ...

The same reversal of the cooperative hydrogen bonding as in 6 and 7 will occur when an anion is incorporated in the hydrogen-bonding sequence, as in 8, or a cation, as in 9. 

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