Synthesis and bioactivity studies of novel Schiff bases and their complexes

Abstract

The new Schiff base (L) “4‐[(2,4‐dimethoxy‐benzylidene)‐amino]‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydro‐pyrazol‐3‐one” was synthesized from 2,4‐dimethoxy‐benzaldehyde and 4‐amino‐1,5‐dimethyl‐2‐phenyl‐1,2‐dihydropyrazol‐3‐one, and the geometry of Schiff base was characterized and determined by proton nuclear magnetic resonance (1H‐NMR), mass, Fourier transform infrared (FT‐IR), and ultraviolet‐visible (UV‐vis) spectroscopy. Schiff complexes of Ni(II), Pd(II), Pt(IV), Zn(II), Cd(II), and Mg(II) have been prepared by reaction of ion metals with as‐prepared Schiff base. The results showed that synthesized complexes offered 1:2 metal‐ligand ratios. Furthermore, the Schiff complexes were a tetrahedral in complexes Ni(II), Zn(II), Cd(II), and Hg(II), octahedral Pt(II), and square planer complex Pd(II). Additionally, density functional theory (DFT) was applied for calculations of both spectroscopic properties and electronic structure of prepared Schiff bases. Moreover, the Schiff base and its metal complexes have been verified in vitro against Streptococcus, Esherichia coli, Candida albicans, and Candida tropicalis in order to assess their antibacterial potential. The findings indicate that the biological activity augments on complexation reaction.

Spectroscopic characterization for new model from Schiff base and its complexes

“…Finally, the metal ion of these complexes that belongs to d 10 system does not show d–d transition because of full d orbital's. [ 20–22 ]…”

Spectroscopic characterization for new complexes with 2,2′‐(5,5‐dimethylcyclohexane‐1,3‐diylidene)bis(azan‐1‐yl‐1‐ylidene)dibenzoic acid

“…The electronic spectrum of Re(V) complex showed three broad peaks at 489, 637, and other at 715 nm assigned to 3 T 1 g → 3 A 2 g, 3 T 1 g → 3 T 1 g (P), and 3 T 1 g → 3 T 2 g (F) transition, respectively; the magnetic moment value of this complex is consistent with octahedral geometry structure. [ 23,25,26 ]…”

“…3 T 2 g (F) transition, respectively; the magnetic moment value of this complex is consistent with octahedral geometry structure. [23,25,26] F I G U R E 7 IR spectra for ligand…”

Macrocyclic Cr3+, Mn2+ and Fe3+ complexes of a mimic SOD moiety: Design, structural aspects, DFT, XRD, optical properties and biological activity

“…[15] Furthermore, macrocyclic Cr 3+ complexes are famous for their biological influences as anticarcinogenic, antibacterial, and antifungal properties. [16] Manganese and its compounds are widely used in analytical chemistry, metallurgical processes, paints, pigment industry, adsorption into the soil for plant growth [17] and as a catalyst in the replication and transcription of DNA as well as coenzyme (i.e. SOD).…”