3.2.3. Hirshfeld Surface Analysis

The 3D Hirshfeld surface and 2D fingerprint plots of two multicomponent crystals of ARI are given in Figure 7. In their 3D Hirshfeld surface, the large and deep red spots correspond to the close-contact N-H··· O interactions. The H··· H contacts appear as scattered points in the middle region of the 2D fingerprint plots, which were the predominate type of interactions. The relative percentage contributions of H··· H contacts in theARI-SAL salt were markedly lower than that of the ARI-ADI salt acetone hemisolvate and compensated by the C··· H/H··· C contacts shown as a pair of "wings". However, these interactions displayed higher interatomic distance. Interactions with less interatomic distance are presented in fingerprint plots as pointy regions. The reciprocal O··· H contacts, corresponding to O-H··· O, N-H··· O, and C-H··· O interactions, are presented as long, sharp, symmetrical spikes. Additionally, the Cl··· H contacts, corresponding to the Cl··· H-C, Cl··· H-O and Cl··· H-N interactions, appear as a pair of "wings" and have equivalent relative percentage contributions to their own Hirshfeld surfaces.

**Figure 7.** The 3D Hirshfeld surface and 2D fingerprint plots of two multicomponent crystals of ARI.
