Trimorphism of an asymmetric disulfonamide Schiff base

Abstract

An asymmetric Schiff base, H2L, has been prepared by condensation of the selectively functionalised 2-(tosylaminomethyl)aniline (A) with 2-tosylaminobenzaldehyde (B). H2L has been characterised by elemental analysis, FAB-MS, NMR and FTIR techniques. The molecular structure of A has been elucidated by X-ray diffraction methods, as well as four different conformational isomers of H2L, which are present in the three polymorphic forms solved (T_a, T_c and M). Two of these polymorphs (T_c and M) are based on similar dimeric units, which are connected via two intermolecular N–H⋯O bonds, along with some edge-to-face and face-to-face interactions. Molecules corresponding to T_a are differently conformed, and display two intramolecular N–H⋯O and N–H⋯N bonds. In this crystal structure, pairs of neighbouring molecules are connected through simultaneous face-to-face interactions between their two tosyl groups.