How to define hydrogen bonds

Hydrogen bonds play a crucial role in the interactions in proteins and are among the main forces to build up tertiary and quaternary structures. During the PPS-course, the term hydrogen bond was widely used but not well defined.

The following chapters should solve this problem to some extend. They should outline some problems in the 'traditional' way to define hydrogen bonds and will show, how arbitrary they are. Three different models will be introduced, which are all capable to give an unequivocal answer to the question, if a hydrogen bond between two atoms exists or not.

In addition, a simple model to quantify the strength of hydrogen bonds is presented.

The goal of the text is, to give a better understanding, what the problems are, to define weak interactions. It offers no 'real' solution as there doesn't exist the ultimate answer to the question, what a hydrogen bond is.

But allowing us to quantify hydrogen bonds it should give us a better decision, in which cases interactions of hydrogens may be important or not.

• Introduction
• Some coordinations around hydrogen
• How to define hydrogen bonds
  • A geometric model
  • An electrostatic model
  • A quantum chemical model
• Coordination in Brucite
  • The geometric coordination in Brucite
  • The elektrostatic coordination in Brucite
  • A quantum chemical coordination in Brucite
• How to quantify hydrogen bonds
  • The bond valence model
  • Describing O-H bonds using bond valences
  • Some coordinations around hydrogen II
• Summary
• Literature

These pages were created by Jens Lösel. If there are any questions, please mail me