Structural features and N-H…O and O-H…O hydrogen-bonded supramolecular frameworks in 2-methylanilinium hydrogen DL-malate hydrate, 4-methoxyanilinium and 4-methylanilinium hydrogen DL-malate salts

Abstract

In the crystal structure of 2-methylanilinium hydrogen DL-malate hydrate (I), an additional water molecule is present in asymmetric unit. In the crystal structures of 4-methoxyanilinium hydrogen DL-malate (II) and 4-methylanilinium hydrogen DL-malate (III), the hydrogen malate anions exhibit configurational disorder with major component occupy S-configuration and minor component occupy R-configuration provided both (II) and (III) are prepared from a racemic mixture of DL-malic acid. In crystal structures of compounds (I)–(III), the hydrogen malate anions and anilinium cations from O-H…O and N-H…O hydrogen bonds which exhibit interesting supramolecular frameworks. In compound (I), the N-H…O and O-H…O hydrogen-bonded anionic-cationic framework form two-dimensional hydrophilic and hydrophobic layers in which the lattice water molecules are embedded in hydrophilic layers. However, in crystal structures of (II) and (III), the hydrogen DL-malate anions form two-dimensional anionic substructure through O-H…O hydrogen bond, in which the anilinium cations are anchored through N-H…O hydrogen bonds.