Synthesis, Characterization and Nematicidal Activity of Bis-(2-Hydroxy-1- Naphthaldehyde)-O-Phenylenediamine and its Cu2+,Ni2+ and Zn2+ Ions

Schiff base complexes derived from 2-hydroxy-1-naphthaldehyde and o-phenylenediamine and its Ni2+, Cu2+ and Zn2+ complexes have been synthesized. The ligand Bis(2-hydroxy-1-naphthaldehyde)-o-phenylenediamine (BHNOPDA) and its complexes were characterized by molar conductivity, magnetic susceptibility, melting point, solubility test and spectrophotometrically (IR and UV-Vis). The solubility results indicated that the ligand and metal complexes were soluble in methanol, ethanol acetone, diethylether, chloroform, dimethylsulphoxide, dimethylformaldehyde while the melting point of ligand and complexes was found to be between 154-268oC, indicating fairly stable compounds. The complexes had molar conductivity of 46.3-54.10 indicating an electrolytic property. The IR spectrum of BHNOPDA showed characteristic vibrations of C=N and OH groups at 1610.09 and 3471.91 cm-1, respectively. The spectra of Cu2+, Ni2+ and Zn2+complexes, the azomethine band v(C=N) was shifted to lower wave number (1580.21–1606.47 cm-1) whereas, the v(OH) is shifted to lower frequency upon complex formation suggesting involvement of C=Nand OH groups in coordination. UV-Vis spectrophotometer showed a complexation of the metal and ligand, demonstrating a tetrahedral geometry for both the ligand and the complexes. The magnetic susceptibility values indicated that Cu2+ and Ni2+ complexes are paramagnetic, while Zn2+ complex is diamagnetic.The ligand and its metal complexes were screened for nematicidal activities against a root knot nematode.Hatching and mortality test of the ligand and its metal complexes against Meloidogyne incognita showed an enhanced activity of the metal complexes as compared to the free ligand.