Synthesis and spectroscopic characterization of transition metal complexes derived from novel benzofuran hydrazone chelating ligand: DNA cleavage studies and antimicrobial activity with special emphasis on antituberculosis

Abstract

Mononuclear divalent complexes of Co, Ni, Cu and Zn derived from a benzofuran‐based novel hydrazone tridentate ligand were synthesized and characterized using various spectroscopic methods. Elemental analysis reveals that the metal‐to‐ligand ratio is 1:2 which is supported by mass spectrometry results. Conductivity measurements suggest that all the complexes are non‐electrolytic in nature. The ligand and complexes were evaluated for their antimicrobial potency. Bioassay of all hydrazone chelates shows enhanced activity as compared to that of the ligand. The complex with cobalt ion as the metal centre shows better activity against fungi than the standard. Also, ligand and complexes were screened for antituberculosis activity; some analogues (Ni, Cu, Zn) are eight times more active than the standard. Both ligand and complexes show moderate ability to cleave calf thymus DNA. Copyright © 2015 John Wiley & Sons, Ltd.

Thiosemicarbazone ligands based transition metal complexes: A multifaceted investigation of antituberculosis, anti‐inflammatory, antibacterial, antifungal activities, and molecular docking, density functional theory, molecular electrostatic potential, absorption, distribution, metabolism, excretion, and toxicity studies

“…This improvement is attributed to reduced polarity on the metal ion due to the partial redistribution of positive charge with donor groups and delocalization of pi‐electrons within the chelating ring which formed during complexation. The increased hydrophobicity increases the lipophilicity of the metal, facilitating better permeation of the complexes through the lipid layers of thick cell walls, in accordance with Tweedy's chelation theory 15,33 . The augmented TB inhibition ability on complex formation can also ascribed to factors such as metal–drug synergy and the drug transporter properties of the complexes. The complexes (3) and (4) were observed as lowest potent to inhibit the TB dysfunction with 0.059 ± 0.004–0.059 ± 0.005 μmol/mL, whereas (5), (7), and (8) had moderate potency to control the TB although the (6), (9), and (10) have the highest activity to reduce the TB malformation.…”

“…The increased hydrophobicity increases the lipophilicity of the metal, facilitating better permeation of the complexes through the lipid layers of thick cell walls, in accordance with Tweedy's chelation theory. 15,33 The augmented TB inhibition ability on complex formation can also ascribed to factors such as metal-drug synergy and the drug transporter properties of the complexes. 3.…”

Investigation of antituberculosis, antimicrobial, anti-inflammatory efficacies of newly synthesized transition metal(II) complexes of hydrazone ligands: structural elucidation and theoretical studies

“…The obtained pattern states that the complex (4) has amorphous nature while its ligand (1) shows crystalline nature (supplementary Fig. S15 ) 51 . The average crystallite size and dislocation density 52 of the ligand (1) were calculated by using the below Eqs.…”

Transition metal complexes of a novel quinoxaline‐based tridentate ONO donor ligand: synthesis, spectral characterization, thermal, in vitro pharmacological and molecular modeling studies

“…The third band observed at ca 725 nm is due to 3 A 2g (F) → 3 T 1g (F) transition for octahedral geometry . The Cu(II) complex shows three bands, at 231, 361 and ca 465 nm, and are assigned to π–π*, n–π* and 2 B 1g → 2 B 2g transitions, respectively, indicating that the complex has distorted octahedral geometry . The Zn(II) complex is expected to have octahedral geometry and exhibits two intra‐ligand bands corresponding to π–π* and n–π* transitions.…”