Gamma-ray irradiation and characterization of synthesized bidentate and tetradentate Schiff base ligands and their complexes with some transition metal ions

Abstract

Salen ligands are essential for coordinating a diverse group of metals in their respective oxidation states. This creates significant complexes of salen metals that are used in different fields. Condensation of ehylenediamine (en) with p-methoxybenzaldehyde (L1) or o-hydroxyacetophenone (L2) with a ratio 1: 2 (en: p-methoxybenzaldehyde or o-hydroxyacetophenone) or by the interaction of o-phenylenediamine (phen) with o-hydroxybenzaldehyde (L3) or p-hydroxybenzaldehyde (L4) with a ratio 1: 2 (phen: o-hydroxybenzaldehyde or p-hydroxybenzaldehyde) has been used to prepare four symmetrical Schiff bases (L1-L4). The UV–vis spectroscopy has been used to investigate the diverse electronic transitions associated with the Schiff bases molecules as well as how these transitions are impacted by diverse polarities of solvents. Elemental analysis, FT-IR, UV–vis spectra, molar conductivity, and 1H NMR have been used to characterise all the compounds obtained in this process. The continuous variation applied alongside molar ratio spectral methods showed the formation of different complexes arising from the reaction of the ligand (L1-L4) with the metal ions Mn(II), Fe(III) and Cu(II) is 1: 1 and/ or 1: 2 (M: L). A series of universal buffer solutions (20 % ethanol v/v) with varying pH values were used in spectrophotometry to determine the acid dissociation constants of the L2 and L4 ligands. Gamma radiation was applied to examine the compounds’ irradiation stability. Additionally, the absorptions of the main functional groups were screened using FT-IR spectra before and after Gamma irradiation. The results show that all the compounds are stable after irradiation process; therefore, it could be used as enhancing agents in cancer therapy.

Keywords

• Schiff base
• Universal buffer
• Stoichiometric determination
• Formation constant
• Gamma radiation