A new carboxylic chelate ligand and its supramolecular complexes formed with sodium ions and alcohol molecules

The new hydrazone ligand 1, featuring a 2-carboxy group at the aromatic ring and a trifluoromethyl structural modification in the pentane-2,4-dione moiety, has been synthesised via the Japp–Klingemann route. The compound is shown to form binuclear multicomponent chelate complexes (2 and 3) composed of two sodium ions, two charge equalising carboxylates of the hydrazone molecule, two more carboxylic hydrazones and two alcohol solvent molecules, with the latter being either EtOH or n-BuOH. X-ray crystal structures of the free hydrazone ligand as well as of the complexes have been studied. They demonstrate for the free ligand a ribbon-type aggregation of carboxylic dimers, while the isomorphous complexes possess a remarkable binuclear structure with the two sodium ions in a distorted octahedral coordination geometry of six oxygen atoms coming, at the equatorial and apical sites, from the hydrazone carbonyl groups and the hydroxyl of the solvent molecules, respectively. The hydrogen bonds owing to the alcohol molecules give rise to the stack formation of the supramolecular cluster. Weak intermolecular contacts involving the fluorine atoms also contribute to the crystalline packing in the case of both the free ligand and the complexes.