Synthesis of novel metal (II) complexes tailored from 9-oxo-9H-fluorene-1-carboxylic acid via green protocol: DNA cleavage and anticancer studies

[Display omitted] •The manuscript describes the synthesis of two new hydrazone Schiff base ligands.•Synthesis of metal complexes from greener protocol.•Structure of compounds was confirmed by analytical and spectroscopic methods.•DNA cleavage, DAPI staining and anticancer activity studies were carried out.•Compounds are more active towards A549 cell line than the standard drug Paclitaxel. Despite being a polycyclic aromatic compound, fluorenone is not classified as carcinogenic. Some of the derivatives of fluorenone and metal complexes embedded with fluorenone based ligands exhibited challenging biological activities, including anticancer activity. The current investigation hence focuses on synthesis, characterization and anticancer activities of fluorenone based ligands and their coordinate compounds of some first row transition metals. The stoichiometry of all the synthesized metal complexes is found to be 1: 2 (metal: ligand) with the general formula [M(L)2], L = singly deprotonated ligand, whereas the geometry of all the metal complexes is found to be octahedral. The synthesized ligands and their respective metal (II) complexes were found to cleave the pBR322 DNA, during gel electrophoresis studies. The inhibition of cancer cell growth has been confirmed by fluorescence imaging techniques using DAPI as staining dye. The IC50 values of ligands and their metal (II) complexes suggest that synthesized compounds are more active towards A549 (human lung adenocarcinoma) cell line when compared with the standard drug Paclitaxel. In case of MCF-7 (human breast carcinoma) cell line, compound Cu(L2)2 is found to be more active than the standard drug Paclitaxel.