IsoStar - a knowledge-based library of intermolecular interactions
IsoStar is a web application that provides thousands of interactive 3D scatterplots that show the probability of occurrence and spatial characteristics of interactions between pairs of chemical functional groups. Accessed using just a few intuitive button clicks these scatterplots facilitate the rapid exploration and assessment of intermolecular interactions without the need to construct complex search queries, or carry out detailed data analyses.
IsoStar contains information on intermolecular interactions derived from both small-molecule crystal structures in the Cambridge Structural Database (CSD) and from protein-ligand interactions observed in the Protein Data Bank (PDB). Interaction energies, computed using intermolecular perturbation theory (IMPT), are also included for many important systems.
IsoStar information on the frequencies and directionalities of intermolecular contacts is particularly relevant to medicinal chemists interested in identifying bioisosteric replacements and to molecular modellers engaged in structure-based drug design.
H-bonded O-H contacts around aliphatic
ester groups: the majority of these bonds
form to the terminal –C=O rather than the
Contoured interaction-density plot for the
distribution of carbonyl contact groups
around a phenyl central group. Red
denotes regions most preferred by
the carbonyl O atoms.
Each scatterplot in IsoStar has been pre-calculated by searching the CSD or PDB for nonbonded interactions between a pair of functional groups A and B. The A...B contacts are transformed so that the A groups are least-squared superimposed. The resulting scatterplot shows the experimentally observed distribution of B (the contact group) around A (the central group).