Related Experiment Video
Updated: May 12, 2026
Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
Synthesis, structural characterization, DFT calculation, and antitumor activity of a new Co(II) complex based on
Bing-Lin Sui1, Li-Hua Wang2, Xi-Shi Tai3
1College of Chemistry and Chemical Engineering, Weifang University, Weifang, 261061, P. R. China.
Abstract:
In this work, a new Co(II) complex, abbreviated as [Co(L)(bipy)(H2O)2]n (1) was prepared using cobalt(II) acetate tetrahydrate, 2-((2'-carboxybenzyl)oxy)benzoic acid (H2L), and 2,2'-bipyridine (bipy) ligands in a mixture solution of ethanol and water (v: v = 3: 1). The structure of the complex (1) was analyzed by elemental analysis (EA), infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TG), and single-crystal X-ray diffraction techniques. The complex (1) crystallizes in the monoclinic space group C2/c, featuring a distorted octahedral [CoO₄N₂] coordination sphere, by two oxygen atoms from the carboxylate groups of two 2-((2'-carboxybenzyl)oxy)benzoate (L) ligands, two oxygen atoms from coordinated water molecules, and two nitrogen atoms (N1 and N2) from a single 2,2'-bipyridine (bipy) ligand. Bridging carboxylate ligands (L) form a 1D chain, which extends into a 2D layer via π-π interactions of the 2,2'-bipyridine ligands (bipy). The DFT calculations of the complex (1) indicates that the HOMO is predominantly distributed on the oxygen and nitrogen atoms bonded to Co(II) ion, but the LUMO is mainly localized around distributed in the six-membered carbon ring adjacent to the Co(II) ion. Electrostatic potential calculation of the complex (1) shows that the regions with higher electrostatic potential are mainly located on the aromatic ring, whilst the lower electrostatic potential regions are primarily located near the oxygen and nitrogen atoms. The electrochemical behavior of the complex (1) was investigated in acetonitrile and 1 mol·L⁻¹ sulfuric acid. In ACN/TBATFB, the complex (1) exhibits a well-defined, predominantly reversible Co(III)/Co(II) redox couple, indicating good electrochemical stability, whereas in 1 mol·L⁻¹ H₂SO₄, a significantly different redox response with enhanced anodic currents and a prominent oxidation peak is observed, arising from the synergistic effect of ligand protonation-oxidation processes and the metal-centered Co(III)/Co(II) redox couple under acidic conditions. The cytotoxicity of the complex (1) and CoCl₂ was evaluated against L02, PANC-1, and MCF7 cell lines using the MTT assay. The complex (1) exhibited lower IC₅₀ values and higher selectivity for cancer cells than CoCl₂, attributable to improved cellular uptake and ROS-mediated oxidative stress, whereas free Co²⁺, which stimulated cell proliferation at low concentrations, the complex (1) showed no growth-inducing effect, highlighting its potential as a cobalt-based anticancer agent.
Related Concept Videos
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:42Valence Bond Theory
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
00:43Complexometric Titration: Ligands