Ionic hydrogen bonding

Ayotte P, Bailey C G, Weddle G FI and Johnson M A 1998 Vibrational spectroscopy of small Br (Fl20) and I Fl20) clusters infrared characterization of the ionic hydrogen bond J. Phys. Chem. A 102 3067-71... 

Meot-Ner M 1984 Ionic hydrogen bond and ion solvation 2. Solvation of onium ions by 1-7 water molecules. Relations between monomolecular, specific and bulk hydration J. Am. Chem. Soc. 106 1265-72... 

The location of the hydrogen atoms in hydrogen bonded systems is often difficult to ascertain. When X-ray diffraction is used there is an experimental limitation to face, as it is usually difficult to locate the very light H-atom in Fourier maps and, even when this is possible, the technique can provide information on electron density centroids rather than on the position of the light nucleus. Neutron diffraction is required for an unambiguous location of the H-atom. In ionic hydrogen bonds the situation may occur where a knowledge of the proton position in a donor-acceptor system is necessary to know whether proton transfer, i.e. protonation of a suitable base, has occurred or not. 

Numerous examples of ionic hydrogen bonds (e.g., in ref. 14) are addressed complexes that are formed as... 

Sallenave X, Bazuin CG. Interplay of ionic, hydrogen-bonding, and polar interactions in liquid crystalline complexes of a pyridylpyridinium polyamphiphile with (azo)phenol-functionalized molecules. Macromolecules 2007 40 5326-5336. 

The X-ray crystal structure determination of a number of simple guanidinium salts " (e.g., methylguanidinium dihydrogenphosphate) clearly demonstrates the existence of bidentate ionic hydrogen bonds as shown in Figure 10, with N(H)—0 contacts in the region of 2.9... 

In the case of intercalates we have seen how the inclusion of guests swells the layers, such that the materials respond dynamically to the intercalation process. We now turn to a different approach in which a crystal engineering based design strategy has created rigid, well-defined materials based on ionic hydrogen-bonded solids in which polar guanidinium disulfonate layers - (C(NH2)3+)2... 

Having introduced the major principles of complexation, association, and organization, it is important to review the physicochemical forces that lead to supramolecular ensemble formation. As mentioned above, supramolecular interactions are by definition noncovalent. In the order of the polarity of the partners involved, they comprise ionic or electrostatic interactions,17 18 ion-dipole interactions,19 dipole-dipole interactions, (ionic) hydrogen bonding, cation-tt and anion-tt interactions,... 

Scheme 6.10 Aza-Henry reactions catalyzed by polar ionic hydrogen-bonding.

Aza-Henry Reaction Catalyzed by Polar Ionic Hydrogen Bonding [15] (p. 221)... 

Fig. 2.1.2. Chiral artificial receptors for the recognition of carbohydrates via ionic hydrogen bonds involving anionic acceptors [1].

Noncovalent interactions are weak inter- or intramolecular interactions that result from a combination of electrostatic interactions (ionic), hydrogen bonding, hydrophobic interactions (stacking or intercalation), and van der Waals interactions (dipole-dipole or induced dipole-induced dipole). Complexes formed by these types of interactions are usually fragile. This property is often essential to their biological function, which depends on the equilibria between the associated and free forms of these molecules. 

Interdigitation of the organic substituent of the sulfonate ions on adjacent layers and ionic hydrogen bonding predictably leads to a broad series of laminar architectures. It should be noted that there are several key differences between guanadinium sulfonates and alkylammonium trimesates ... 

In this case, the solvent-induced H chemical shift of ca. 1 ppm is best explained by assuming a double-minimum potential model of the hydrogen-bond, ie. the existence of a rapid solvent-dependent proton-transfer equilibrium between (a) the covalent and (b) the ionic hydrogen-bonded complex. With increasing solvent polarity, the proton-transfer equilibrium is shifted in favour of the ionic complex (b). 

This concept has been extended using a poly(aniline) as the main conductive polymer (Fig. 61) [215]. Again, a main chain polymer poly(acrylnitrile) able to form ionic hydrogen-bonded complexes (2-acrylamido-2-methyl-... 

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