What do imf's (intermolecular forces) have to do with the idea that structure effects function?

The intermolecular forces present determine the shape of a molecule. This is extremely important in the case of protein molecules which have a very specific shape, especially enzymes. This shape is a direct result of intermolecular forces, and the intermolecular interactions are classified within the primary, secondary and tertiary structure of the protein. This is also why proteins denature when heated, because these intermolecular interactions are broken or disrupted.

Intermolecular forces affect several measurable properties of substance , such as :
- Melting and boiling points
- Viscosity
- Surface Tension
- Vapour pressure

hope this helps