Synthesis, Spectroscopic and Thermal Characterization and Antioxidant Activities of Three Schiff Bases Derived from Aminophenol

Abstract

The main objective of this work is synthesized three Schiff bases: (E)-2-(((2hydroxyphenyl)imino)methyl)-6-methoxyphenol (I), (E)-2-(((3-hydroxyphenyl) imino)-Methyl)-6-Methoxyphenol(II) and (e)-2-(((4-hydroxyphenyl)imino)methyl)-6amethoxyphenol(III) derivative of 2-hydroxy-3-methoxybenzaldehyde and ortho/meta / para-aminophenol, their structures were confirmed by spectroscopic methods: UV-Vis, FTIR, ( 1 H, 13 C NMR). Firstly, a thermogravimetric analysis (TGA/DTG) study of the composite Schiff bases proved them to be thermally stable. Secondly, the study of the biological properties of the synthesized compounds allowed the evaluation of the antioxidant activity by conventional methods (scavenging of the DPPH radical, and bleaching of ß-carotene). The results demonstrated a variable degree of inhibitory effects on the growth of synthesized Schiff bases.

Antioxidant Properties Schiff Base and Iron(II) Complex: Synthesis and Characterization

“…Further evidence for the complexation process is provided by the appearance of a low intensity broad band at 406-495 nm in the electronic spectra of the Fe(II) complex, which is not present in the spectrum of the free ligand. In the structure of the metal chelates studied, this band could be mainly ascribed to the d → d transition [9][10][11].…”

“…The medium intense band observed at 1173 cm -1 , due to the phenolic C-O stretching of ligand, was also changed to higher wavenumbers (1177 cm -1 ), revealing the involvement of the coordinating phenolic oxygen. Furthermore, clear evidence for the coordination of the azomethine nitrogen, carbonyl and phenolic oxygen atoms to the metal ion was provided by the appearance of two non-ligand weak bands at 503-576 cm -1 and 470 cm -1 due to υ(Fe-O) and υ(Fe-N), respectively [4,[8][9][10][11].…”