Structural, spectroscopic and computational study of 5-(substituted phenylazo)-3-cyano-1-ethyl-6-hydroxy-4-methyl-2-pyridones

Abstract

Ten 5-(substituted phenylazo)-3-cyano-1-ethyl-6-hydroxy-4-methyl-2-pyridones were studied (five new compounds) to provide insight into the electronic effects of diverse substituents located at different positions in their phenyl moieties. The structural features of these dyes were examined by combining experimental and theoretical approaches. The crystal structures of two derivatives were revealed by X-ray crystallography and diverse packing modes owing to different intermolecular interactions (- stacking and lone pair- interactions, as well as hydrogen bonds) were found. A study on lattice energy and energy related to the molecular pairs obtained from their crystal packing was performed. The tautomerism and ionisation of the dyes in ethanol or N,N -dimethylformamide solution were rationalised in terms of diazo component substitution pattern.