Synthesis and Spectroscopic Characterization of some Mixed Schiff Base Complexes

Two different Schiff bases have been synthesized, the first Schiff base derived from the reaction of 2-hydroxyacetophenone and amino acid (tyrosine) as primary ligand (HL1) and the second Schiff base formed from the condensation of 4-dimethylaminobenzaldehyde and of 2-aminobenzoic acid as secondary ligand (HL2). These Schiff bases were used to form mixed Schiff base complexes with Co (II), Ni (II), Cu (II), Zn (II) and Fe (III) ions in the presence of alkaline media. The synthesized Schiff bases and their complexes have been investigated by using several techniques, in terms, CHN elemental analyses, molar conductivity, magnetic moment and spectroscopic studies [IR, UV-Vis, 1HNMR, MS and EPR spectra]. The CHN elemental analysis data showed the formation of the mixed Schiff base complexes in 111 [ML1L2] ratio. The molar conductance measurements revealed that the mixed Schiff base complexes are electrolytes confirming the existence of sodium ions outside the frame of the complexes except Iron (III) complex which is non-electrolyte in nature. Room temperature magnetic moment values suggested that the complexes have six-coordinate geometry. Infrared spectral results exhibitedtheSchiff bases coordinated to the metal ion via the oxygen atom of -COOH and the nitrogen atom of azomethine and phenolic groups. The signals which obtained from The 1HNMR spectra of the Schiff bases and their Zn (II) Schiff base complex supported the complexation between the Schiff bases and Zn (II) ion. Whereas, The UV spectral results of the Schiff bases showed * (Phenyl ring) and n* (C=N, -COOH and OH) transitions and the UV-Vis spectral data of the mixed Schiff base complexes suggested the geometrical structure which is an octahedral geometry around the metal ions. The mass spectral fragmentations of the Schiff bases and their Cu (II) complex were studied and confirming the formation of the Schiff bases and the iron (III) mixed Schiff base complex. The electron paramagnetic resonance spectral values confirmed the data which are obtained from UV-Vis study.