Strong Orientational Effects Hydrogen Bond

One can roughly classify hydrogen bonds according to the nature of the two atoms to which the hydrogen is linked. The corresponding energies are given in Table 15.1.1. 

ENERGIES OF HCyDROGEN BOND (DAVIES [1946], alSO CODLSON [1952] p. 301) 

Another classification is based on the nature of the molecular aggregate formed by the hydrogen-bonds. Hydrogen bonds can form bimolecular complexes. This is exemplified by the association in acids which produces dimers of the form 

Another example, corresponding to hydrogen bonds between unlike molecules, is 

Sometimes the association leads to the formation of chain-like or closed ring ag egates as in fluorhydric acid 

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Scatena, L. F., Brown, M. G. and Richmond, G. L. (2001) Water at hydrophobic surfaces weak hydrogen bonding and strong orientation effects. Science, 292, 908-912. 

L. F. Scatena, M. G. Brown, and G. L. Richmond, Science, 292, 908 (2001). Water at Hydrophobic Surfaces Weak Hydrogen Bonding and Strong Orientation Effects. 

To measure the effect of the presence of ions on the hydrogen-bond structure of bulk water, we studied the concentration dependence of the orientational relaxation of bulk water in aqueous solutions of Mg(C104)2. We chose Mg(C104)2 because Mg2+ is considered to be a strong structure-making ion the viscosity of 1 M Mg(C104)2 is about 30 %... 

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