Synthesis and structural characterization of a palladium complex as an anticancer agent, and a highly efficient and reusable catalyst for the Heck coupling reaction under ultrasound irradiation: A convenient sustainable green protocol

Abstract

The complex [Pd(paOH)2].2Cl (1) was synthesized by the self-assembly method with palladium chloride and pyridine-2-carbaldehyde-oxime (paOH) in aqueous acetonitrile solution under ambient conditions. Complex 1 was fully characterized by FT-IR, UV–vis and NMR spectroscopic techniques, as well as elemental analysis. The single crystal X-ray structure of complex 1 indicates that the Pd(II) ion is bonded to four nitrogen atoms from two pyridine-2-carbaldehyde-oxime ligands. The molecular geometry of the Pd(II) ion in complex 1 is distorted square-planar with a trans geometry and with two free chloride ions. Using an MTT assay, the anticancer activities of the palladium complex 1 were studied with respect to human breast cancer (MCF-7) and hepatocellular carcinoma (HePG-2) cell lines. The data obtained show that complex 1 displays strong activity towards the viability and the growth of the cancer cell lines MCF-7 and HepG2. Additionally, complex 1 exhibits excellent catalytic activity for the Heck cross-coupling reaction with water as the solvent under ultrasound irradiation. Ultrasound irradiation not only enhanced the rate and the yield of the reaction, but also promoted the in situ generation of a well-dispersed zero-valent Pd-colloidal species as the active catalyst from complex 1. Finally, the luminescence spectrum of complex 1 is discussed.