3.10. Hirshfeld surface investigation
The Hirshfeld surfaces analysis (3D) and fingerprint plots (2D) are two
necessary approaches to evaluate and complete the structural
description, both were carried out with Crystal Explorer 3.1 software
[67] imported on CIF files. 3D graphics provide a three-dimensional
image of intermolecular and intramolecular interactions in crystals,
while two-dimensional plots obtained by Hirshfeld surface analysis can
identify each type of intermolecular interaction, they are based on thede and di distances to
identify the nature of contacts where the term decorresponds to the distance separating the Hirshfeld surface and the
nearest atomic nucleus located outside on this surface. As for the termdi , it corresponds to the distance separating the
Hirshfeld surface from the nearest atomic nucleus located inside the
surface. These two terms are connected with the van der Waals rays by
the normalized distance (dnorm ) according to the
following equation:
\(d_{\text{norm}}\) =\(\frac{d_{i}-r_{i}^{\text{vdW}}}{r_{i}^{\text{vdW}}}\) +\(\frac{d_{e}-r_{e}^{\text{vdW}}}{r_{e}^{\text{vdW}}}\)
Chloroquin molecular Hirshfeld surfaces were generated using standard
high resolution. The dnorm surface (Fig. 10a) is
mapped on a color scale varying from -0.388 to 1.402, the ShapeIndex graph (Fig. 10b) located in the color range of -1.0 - 1.0
and Curvedness in the range of -4.0 to 4.0 (Fig. 10c).