Pesticidal studies of an azo based heterocyclic Schiff base and its transition metal complexes
By Hemant Kumar and Ram Pal Chaudhary
The condensation of dialdehyde (III), obtained from p-nitro benzoic acid, with 2-amino-5-chloropyridine yielded an heterocyclic ligand bis(2-(5-chloropyridin-2-ylimino)phenyl)-4,4'-(diazene-1,2-diyl)dibenzoate (BCDD, L). The ligand was further converted to metal chelates with some divalent transition metal ions viz., Co(II), Ni(II), Cu(II) and Zn(II). The synthesized complexes were characterized through elemental analyses, IR, NMR and electronic spectral data. The ligand BCDD acts as a hexadentate ligand and forms six-coordinated complexes with all these metal ions through two imine nitrogen’s, two carbonyl oxygen’s and two pyridine nitrogen’s as 1:1 (metal : ligand) stoichiometry. Distorted octahedral geometry was suggested for all the metal complexes. The ligand and its complexes have been screened for their antipestal activities towards Tribolium castaneum, a red flour beetle as a storage food grain pest commonly found in India. The results showed that the metal complexes have higher antipestal activities as compared to ligand BCDD. The order of antipestal activities was Cu(II)L > Zn(II)L > Ni(II)L > Co(II)L > L.
Key words: Heterocyclic Schiff base, ligand, transition metal complexes, antipestal activities.
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