Series of pyridine-2,6-dicarbohydrazide aroyl hydrazone ligands: synthesis, characterization and crystal structures

Abstract

The work described in this thesis concerns the synthesis of aroylhydrazone ligands. The aroylhydrazone ligands bis[4-phenylbenylidene]pyridine-2,6- dicarbohydrazide (L1), bis[4-(4-pyridyl)benylidene]pyridine-2,6-dicarbohydrazide (L2), bis[3-cyanobenylidene]pyridine-2,6-dicarbohydrazide (L3) and bis[3-cyanobenylidene]pyridine-2,6-dicarbohydrazide (L4) were synthesized by condensation reactions of pyridine-2,6-dicarbohydrazide with 4-phenylbenzaldehyde, 4-(4-pyridyl)benzaldehyde, 3-cyanobenzaldehyde and 2,3,4- trihydroxybenzaldehyde, respectively. These ligands have been characterized by Mass spectrometry, Infrared spectroscopy, and NMR spectroscopy. The molecular structures of ligands (L1-L4) and their three dimensional supramolecular interactions have been investigated by single crystal X-ray diffraction analysis. It was found that all studied hydrazones adopt the E configuration around the imino N=C group in the solid state. The association modes in the studied crystals are dominated by strong hydrogen bonds of the N−H…O type involving the amide group as a proton donor.