DFT, TD-DFT and Biological Activity Studies of Some Maleanilic Acid Derivatives Ligands and Their Organometallic Complexes

Abstract

This study is a complementary study to our previous study that included the synthesis and characterization of some maleanilic acid derivatives ligands (L^1-4) and their metal carbonyl complexes (2-4)_a-d as effective compounds for cancer cell inhibition against three cancer cell lines: HCT-116 (colon cancer), HepG-2 cells (Hepatocellular cancer) and MCF-7 (breast cancer). The activity data manifested that p-nitrophenyl maleanilic acid ligand (L2) and its chromium complex (2b) showed higher inhibitory than the other complexes against the tested cancer cells. Additionally, DFT and TD-DFT studies were performed to investigate their frontier molecular orbital (FMO), optical properties, and the correlation between the structure and biological activity. The calculated optical energy gap (E_g) was in the range of 1.78- 2.13 eV, and electron cloud delocalization of HOMO/LUMO levels revealed that all complexes show effective charge separation. DFT results show a great relation between E_g values of the carbonyl complexes and their experimental biological activity. Where it was obvious that complex (2b) with the lowest (E_g) value exhibits the highest inhibition potency against cancer cells. In contrast, complex (2d) with the highest (E_g) value exhibits the lowest inhibition potency. These results translate the reverse relationship between E_g values of the complexes and the inhibition potency against cancer cells.