Effect of Substituent Exchange on Optical Anisotropy in Multicomponent Isostructural Materials Containing Sulfathiazole and 2-Aminopyridine Derivatives

Abstract

Four isostructural, multicomponent materials containing sulfathiazole and 2-aminopyridine substituted in the para position by H/CH3/Cl/Br have been investigated. The crystal structures of these solids were determined using data from single-crystal X-ray diffraction measurements. The similarity of the crystal packing was studied using XPac and CrystalCMP programs as well as the packing similarity tool implemented in the Mercury software. The analysis of quantitative similarity parameters showed that the least similar geometrical arrangement is observed for H → Br interchange, while Cl → CH3 exchange has the smallest influence on the molecular packing. These can be easily explained by the differences in the size and properties of the 2-aminopyridine substituent. Refractive indices of all materials were measured using the immersion oil method and calculated using the (Q)LFT approach. The observed variations in refractive indices were discussed in relation to the packing of the structural components and were correlated with the variations in polarizabilities of 2-aminopyridine derivatives.