Computational chemistry and molecular modelling

Approximate molecular orbital methods, such as Hückel Theory, have been useful in helping chemists develop ideas and understanding of molecules.

However, the development of computers, and sophisticated ‘ab initio’ molecular orbital methods (based on the same basic approaches such as the variational principle), mean that it is now possible to calculate molecular properties on desktop PCs. Nowadays, computers are important tools in nearly all areas of chemical research.

For example:

· Pharmaceutical industry (e.g. drug design)

· Materials science

· Biotechnology

· Catalysis (e.g modelling catalysis in zeolites and transition metal complexes)

· Spectroscopy

· Atmospheric chemistry

· Crystallography

· Reaction dynamics

as well as investigating organic reactivity problems.

Many different computational chemistry and molecular modelling methods are used - you’ll learn about some of these in the future.

To understand a chemical reaction, we need to know the transition state structure for the reaction. Transition states are difficult to study directly by experiment. Instead their structures can be calculated.

For example:

Calculated transition state structure for the reaction in the enzyme phenol hydroxylase:

Here an OH group is being transferred onto the ortho carbon of phenol.

(Phenol hydroxylase is important for biodegradation of aromatic pollutants).