Synthesis, spectral characterization, X-ray crystallography and biological evaluations of Pd(II) complexes containing 4(N)-substituted thiosemicarbazone

Abstract

Four new Pd(II) complexes have been synthesized by reacting equimolar ratio of [PdCl₂(PPh₃)₂] and 4(N)-substituted 4,6-dimethoxysalicylaldehyde thiosemicarbazone ligands in toluene and characterized by UV-Vis, IR and NMR. Single crystal X-ray diffraction studies of 2 and 3 revealed that both the complexes have distorted square planar geometry around palladium ion, in which the ligand coordinates through NS and form five-membered rings. Interaction of complexes with calf thymus DNA (CT-DNA) has been examined by absorption titration, suggesting intercalation. Binding of complexes with Bovine serum albumin (BSA) protein using UV-Visible and fluorescence spectroscopic methods indicated strong binding of complexes to BSA. The antioxidant properties of all the complexes showed moderate activity as compared to standard BHT. The cytotoxicities of the Pd(II) complexes were investigated in vitro against both lung cancer (A549) and human breast cancer (MCF-7) cell lines by using MTT assay and by using (AO/EB and DAPI) staining method for cytological changes in cell lines.

KEYWORDS:

• Pd(II) complexes
• spectroscopy
• single crystal X-ray
• DNA/protein binding
• anti-oxidant activity and cytotoxicity

Acknowledgement

The author D.A. greatly acknowledges UGC, New Delhi, India, for UGC-BSR fellowship (F.25-1/2014-15(BSR)7-26/2007/(BSR) Dated: 05.11.2015. Crystallographic data for 1-4 have been deposited at the Cambridge Crystallographic Data Centre as supplementary publication (CCDC No. 1919184 (complex 2) and 1919185 (complex 3). The data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: [phone]; E-mail: depositccdc.cam.ac.uk].