Controlling Solvate Formation of a Schiff Base by Combining Mechano-chemistry with Solution Synthesis

Abstract

A Schiff base dicarboxylic acid (1) was prepared by condensation of 2-hydroxy-1naphthaldehyde with 5-aminoisophthalic acid. Its solvates with pyridine (2a and 2b) and dimethylformamide (3) were prepared by liquid-assisted grinding and by conventional solvent-based methods. All products were characterised by FT-IR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The structures of 1, 2b and 3 were determined by single crystal X-ray diffraction. 1 was found to be a pure Schiff base, 2b a pyridine solvate and 3 a dimethylformamide solvate monohydrate. In all three structures, the Schiff base molecule appears to be present as the ketoamine tautomer.(