... with 1-phenyl-3-methyl-4-(o-carboxyphenylazo)pyrazol-5-one. by Verma, HS; Mathur, KC (JV Coll., Baraut, Uttar Pradesh (India)); Saxena, RC; Mathur, KC (MM Coll., Modinagar (India). Dept. of Chemistry). [en]. The isolation and characterization of La(III), Pr(III), Nd(III), Gd(III) and Dy(III) chelates of 1-phenyl-3-methyl-4-(o-carboxyphenylazo) pyrazol-5-one on the basis of chemical analysis, magnetic and IR spectral studies, are described. ...