A path based approach to assessing molecular complexity.

An atom environment, path based approach to calculating molecular complexity is described. Based on Shannon's equation, the method transforms the number and diversity of paths emanating from an atom to an atom-complexity from which a number of molecular complexity measures are derived. The method is independent of explicitly predefined features such as ring membership, bond types, chirality or symmetry. These path-based measures of complexity can distinguish subtle differences in molecular structure and an application to the visualization of marketed drugs, including a number of biologics, is presented.