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 derivative ligands (L1-4) and their metal carbonyl complexes (2-4)a-d as effective compounds for cancer cell growth inhibition against three cancer cell lines: HCT-116, HepG-2 cells and MCF-7. The activity data has manifested that the p-nitrophenyl maleanilic acid ligand (L2) and its chromium complex (2b) inhibited the tested cancer cells more effectively than the other complexes. Additionally, DFT and TD-DFT studies are performed to investigate their frontier molecular orbital (FMO), optical properties, and the correlation between the structure and biological activity. The calculated optical energy gap (Eg) is 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. The DFT results show a strong relation between Eg values of the carbonyl complexes and their experimental biological activity, where it is obvious that complex (2b) with the lowest Eg value has the greatest inhibitory potency against cancer cells. In contrast, complex (2d) with the highest Eg value exhibits the lowest inhibition potency. These findings translate the inverse relationship between Eg values of the complexes and the inhibition potency against cancer cells.