Thermochromism in Ni(ii) complexes with schiff base derivatives of 4-aminoantipyrine

Ni(II) complexes of 2-hydroxy-1-naphthylidene-4-aminoantipyrine (I) and salicylidene-4-aminoantipyrine (II) display a change of colour upon heating. The change in II is reversible in the presence of moisture. The thermochromism in crystalline I and II has been studied using differential thermal analysis (DTA), electronic and IR spectroscopy. X-ray powder diffraction and electrical conductivity. Thermochromism in these complexes has been attributed to dehydration.