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Synthesis of four new arene ruthenium(II) complexes [(η 6 -C 10 H 14 )RuCl(MFPdpm)] ( 1 ); [(η 6 -C 12 H 18 )Ru-Cl(MFPdpm)] ( 2 ); [(η 6 -C 10 H 14 )RuCl(PFPdpm)] ( 3 ) and [(η 6 -C 12 H 18 )RuCl(PFPdpm)] ( 4 ) containing dipyrrin ligands 5-(4-fluoro)phenyldipyrromethene (MFPdpm) and 5-(penta-fluoro)phenyldipyrromethene (PFPdpm) have been described. The ligands and complexes have been thoroughly characterized by elemental analyses, spectroscopic studies (ESI-MS, IR, 1 H, 13 C NMR, UV–Vis) and structure of the representative complex 4 determined by X-ray single crystal analyses. DNA binding activities of 1 – 4 have been investigated by UV–Vis and fluorescence spectroscopy and their binding through the minor groove of DNA has been established by molecular docking studies. The complexes 1 – 4 exhibit significant cytotoxicity toward human lung cancer cell line (A549). Cytotoxicity, morphological changes, and apoptosis studies have been evaluated through MTT assay, Hoechst 33342/PI staining, and cell cycle analysis by fluorescence activated cell sorting (FACS). In vitro antitumor activity and cytotoxicity of the complexes lie in the order 4 > 3 > 2 > 1 . [ABSTRACT FROM AUTHOR]

• Promising G-quadruplex binders: chroman derivatives ligands & their BF2-complexes. • These compounds stabilize parallel and mixed hybrid G-quadruplex structures. • In vitro and cellular studies: biophysical analyses demonstrate binding affinity in both contexts. • Molecular docking: computational study supports binding of chroman complexes to G-quadruplex. • Potential fluorescent ligands: these compounds offer new options for G-quadruplex targeting ligands. Currently, G-quadruplex structure targeting strategies are considered as a promising anticancer approach. The purpose of this research is to expand the options for G-quadruplex targeting ligands, particularly emphasizing fluorescent ligands. Our study contributes to the field by providing additional choices for G-quadruplex binders with a notable focus on selectivity towards G-quadruplex topology over duplex DNA. In the search of selective and potent G-quadruplex binders, here we discuss an analysis of a few chroman derivatives ligands named A and C and their respective borondifluoride complexes B and D as a quadruplex targeting compounds which found to stabilize G-quadruplex structure. To investigate the binding characteristics of these molecules with G-quadruplex vs. duplex selectivity, In vitro biophysical studies were performed by steady-state fluorescence, UV–visible titration, fluorescent TO displacement assay, CD thermal melting, circular dichroism spectroscopy, and cellular imaging by employing both telomeric and PRCC G-quadruplex forming sequences. Our investigation shows that these chromam ligands and their complexes are able to selectively bind and stabilize parallel and mixed hybrid topology of G-quadruplex both In vitro and in cellular conditions. A molecular docking and MD simulation study also suggests the binding of these compounds with G-quadruplex conformation. Collectively our study suggests these chroman complexes for the first time as a potentially useful fluorescent chemical product for G-quadruplex specific ligands and expands an option for G-quadruplex targeting ligands. [Display omitted] [ABSTRACT FROM AUTHOR]