Synthesis, characterization, antioxidant and biological studies of some divalent transition metal complexes derived from N', N''-bis(2- aminoethyl)-2,2-diethylmalonimidate and 2,2-diethyl-N1,N3-bis(2- (piperazin-1-yl)ethyl)malonimidic Acid

Abstract

Schiff bases N', N''-bis (2-aminoethyl)-2,2-diethylmalonimidate (L₁) and 2,2-diethyl-N',N''-bis(2-(piperazin-1- yl)ethyl)malonimidic acid (L₂) and their metal complexes of Cr(II), Co(II), Ni(II), and Fe(II) were prepared and characterized for solubility tests, melting point (MP)/decomposition temperatures (DT), conductivity measurements, magnetic susceptibility, FTIR, and UV-Visible spectroscopy. The biological activities of compounds were studied. The compounds were found to be soluble in polar solvents which indicates their possible ionic nature, the melting point (MP) and decomposition temperatures (DT) gave sharp values indicating the purity of the compounds. The results of the conductivity measurement in DMSO show values of < 50 Ω^-1 cm³mol^-1 which is below that of ionic compounds (>50Ωcm³mol^-1 ). The magnetic susceptibility results confirmed the diamagnetic nature of Fe(II), Cr(II) and Ni(II) complexes obtained from both L₁ and L₂ while the complexes Co(II) appeared to be paramagnetic in both ligands. The FTIR results manifested the appearance of azomethine at the wavelength of 1625cm-1 and 1590cm-1 for L₁ and L₂ respectively. These signals shifted to 1669cm^-1 , 1677cm^-1 , 1602cm^-1 , 1667cm^-1 in L1 and 1580 cm^-1 , 1610 cm^-1 , 1690 cm^-1 , 1684 cm^-1 for L₂ of Cr, Fe, Co and Ni complexes respectively. The UV-visible for the complexes were studied at the wavelength range of 200-700nm which indicate the electronic shifts at π-π* and ligand to metal charge transfer. The compounds were screened for antimicrobial and antioxidant and the results show some activities.