Pharmacologically significant tetraaza macrocyclic metal complexes derived from isatin and 3,4-diaminobenzophenone: Synthesis, spectral studies and comparative in vitro biological assessment

Abstract

The 12-membered Schiff base macrocyclic complexes, [Dichloro [5,6;11,12-dibenzophenone-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene-2,3,8,9-diindole] metal(II) [M = Co(II), 1; Ni(II), 2; Cu(II), 3 and Zn(II), 4] were synthesized via template condensation of isatin and 3,4-diaminobenzophenone. These four complexes were characterized employing the analytical, spectral viz., FTIR, NMR, Mass, UV-Vis, EPR, TGA/DTA and SEM. The formation of metal complexes has been confirmed on account of the characteristic band positions in FTIR spectra and resonance signals in NMR spectra while the absorption bands in UV-Vis spectra and magnetic moment analysis signify the geometry of the complexes. However, the EPR study inferred distorted octahedral geometry in Cu(II) complex. The binding profile of the metal complexes (1-4) with CT-DNA was monitored by fluorescence and circular dichroism (CD) spectroscopy coupled with molecular docking studies. The binding constants were found to be highest for complex 3. Further, the hypothesis of preferential binding in the minor groove of double-stranded DNA is supported by CD and docking results. The antioxidative properties showed substantial radical scavenging potency of the complex 3. The comparative in vitro antibacterial study of the metal complexes against different pathogenic microbes (S. aureus, E. coli and C. albicans) revealed enhanced activity for complex 3 which is further certified by its efficacy to resist biofilm formation as investigated by XTT reduction assay.

Novel Nickel (II), Copper (II) and Cobalt (II) Complexes of Schiff Bases A, D and E: Preparation, Identification, Analytical and Electrochemical Survey

“…Different factors are effecting of the electrochemical properties and the redox behavior of the transition metal complexes such as axial ligation degree, charge type, coordination number, division of unsaturation, substitution manner and size of the chelate ring. 49,50,51,52,53,54 In our study to promote an understanding of the redox behavior of nine six-coordinate, three each of Cobalt(II), Copper(II) and Nickel(II) complexes of ligands A, D and E, cyclic voltammetric measurements of the complexes were recorded in ethanolic solution in range from +2.0 to -2.0 V using 0.1 Molar [Bu4N][BF4] at sweep rate of 0.1 V. Sec -1 . Same cell setup was used in all CV measurements and the ferrocene/ ferrocenium couple (Fc/Fc + ), E 1/2 = 0.505 V, ∆Ep= 130 mV) was employed as a criterion.…”

Synthesis, physicochemical and biological characterization of Ni(II) complex with imidazole-4-acetate anion as new antifungal agent

“…There were three absorption bands in the visible area, as well as in near-infrared, characteristic of hexacoordinate and octahedral nickel(II) complexes. Low-energy absorption observed as a broadband at 9450 cm −1 corresponds to electronic transition 3 A 2g (F)→ 3 T 2g (F) (ν 1 ). Another two bands at 16040 cm −1 and 26740 cm −1 are connected with The electronic spectra are the most common way to investigate the interaction of complexes with DNA.…”

“…The complex was obtained from aqueous solutions containing nickel nitrate (V) and imidazole-4-acetate sodium salt (Na(iaa)•H 2 O) in the molar ratio 1:3. A solution of Ni(NO 3 ) 2 •6H 2 O (1 mmol) in 50 cm 3 of distilled water was added dropwise to a stirred solution of Na(iaa)•H 2 O in 50 cm 3 of water. The solution was left to stand at room temperature for seven days.…”

“…The biological activities of nickel complexes in eukaryotic and prokaryotic cells are well documented. [1][2][3][4] Generally, these mechanisms are linked with binding to DNA by intercalation and/or electrostatic interactions as well as with effect on the catalytic activity of proteins leading to block of biosynthesis processes on a cellular level. It seems to be important that the biological properties of Ni(II) complexes depend on physical and chemical properties determined both by metal and ligands.…”

Synthesis, Molecular Docking, Cytotoxicity and Antioxidant Activity Evaluation of Isoindoline-1,3-dione Derivatives

“…This was retrieved from the PDB (Protein Data Bank). Caspase-3 [25] receptor was docked with different ligands (3a-k, standard) using Hex 8.0.0 docking software [26,27]. It is an interactive Molecular Graphics Program that calculates and displays possible docking modes of pairs of protein and DNA molecules and also analyzes protein-ligand docking.…”