Influence of co-ligand on the biological properties of Schiff base metal complexes: Synthesis, characterization, cytotoxicity, and antimicrobial studies

Thamilarasan Vijayan, Jinheung Kim, Mohammad Azam, Saud I. Al-Resayes, Antony Stalin, Balakrishnan Senthamarai Kannan, Arumugam Jayamani, Arumugam Ayyakannu, Sengottuvelan Nallathambi

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In this work, six new mixed ligand Schiff base metal complexes of [M2(L1)(X)2Cl4] type, (where, M = CoII, NiII, CuII, L1 = Schiff base ligand derived from 1-pyrenecarboxaldehyde and 1,4-bis[3-aminopropyl]piperazine and X = pyrazine-2-carboxylic acid or 2,2′-biimidazole) were synthesized and studied their biological activity and cytotoxicity. The synthesized Schiff base ligands, their metal complexes were characterized by Infrared, UV-Visible spectroscopy, and elemental analysis. Density functional theory calculations were performed to examine the molecular geometry and frontier molecular orbital properties of complexes (1–6). The DNA binding ability of these complexes (1–6) was evaluated by in vitro spectroscopic (absorption and fluorescence) titrations, viscosity measurements, and in silica by molecular docking measurements. The results showed a good binding propensity with the binding constant from 2.65 × 104 to 3.38 × 105 M−1 in the order 6 > 5 > 4 > 3 > 2 > 1, respectively. All complexes exhibited a good binding affinity to BSA proteins with relatively higher binding constant values similar to the trend of DNA binding studies and where Cu (II) complexes have greater efficiency than Co (II) and Ni (II) complexes. The in vitro cytotoxic study of all the complexes was investigated in the cervical cancer (HeLa) cell line, which displayed IC50 values of 1.36–24.2 μM, signifying the potential of complexes for an operative anticancer drug. Metal complexes were also screened for antimicrobial properties, which showed virtuous inhibition than the free ligands.

Original languageEnglish
Article numbere6542
JournalApplied Organometallic Chemistry
Issue number3
StatePublished - Mar 2022

Bibliographical note

Funding Information:
The authors gratefully acknowledge to Indian Council of Medical Research (ICMR) New Delhi Vide Project No. 52/1/2018/BMS for financial assistance. The authors gratefully acknowledge the financial support given by the RUSA‐Phase 2.0 grant (vide Letter No. F. 24‐51/2014‐U [TNMulti‐Gen]), Government of India, and DST‐PURSE‐II New Delhi to Department of Industrial Chemistry, Alagappa University, Karaikudi‐3, Tamil Nadu. The authors acknowledge the financial support through Researchers Supporting Project number (National Plan for Science, Technology and Innovation, RSP‐2021/147), King Saud University, Riyadh, Saudi Arabia.

Publisher Copyright:
© 2021 John Wiley & Sons, Ltd.


  • DFT calculation
  • DNA/protein binding studies
  • antimicrobial activities
  • cytotoxic study
  • metal complexes


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