Utilizing Hirshfeld surface calculations, non-covalent interaction (NCI) plots and the calculation of interaction energies in the analysis of molecular packing

The analysis of atom-to-atom and/or residue-to-residue contacts remains a favoured mode of analysing the molecular packing in crystals. In this contribution, additional tools are highlighted as methods for analysis in order to complement the `crystallographer's tool', PLATON [Spek (2009). Acta Cryst . D 65 , 148–155]. Thus, a brief outline of the procedures and what can be learned by using Crystal Explorer [Spackman & Jayatilaka (2009). CrystEngComm 11 , 19–23] is presented. Attention is then directed towards evaluating the nature, i.e . attractive/weakly attractive/repulsive, of specific contacts employing NCIPLOT [Johnson et al. (2010). J. Am. Chem. Soc . 132 , 6498–6506]. This is complemented by a discussion of the calculation of energy frameworks utilizing the latest version of Crystal Explorer . All the mentioned programs are free of charge and straightforward to use. More importantly, they complement each other to give a more complete picture of how molecules assemble in molecular crystals.