This link has a short paragraph on the very first page, which says: "There are two useful criteria to evaluate the presence and the strength of a H-bond. The first is to look at the distance between the H and the A atom, which should be shorter than the sum of their Van der Waals radii. A second method suggests to evaluate the angle formed by X-H∙∙∙A, centered on the H atom: the closer this angle is to 180°, the stronger the H-bond is"
I wish to understand why the part in bold is true, that is, what is the angle dependence (qualitative or quantitative) of the strength of hydrogen bonds.
To add to the above discussion, in an introductory biology course at university, we were also given the following example -
Well, once again, why is it so?
I did some research, didn't really find much, but came across an interesting paper that may be worth a read if anyone's really interested. Attaching it here!
Thanks in advance!