Experimental and computational studies of fluorene derivatives containing two identical quinoline and pyridine moieties

Abstract

A new pair of fluorene derivatives, 8,8′-(((9,9-dihexyl-9H-fluorene-2,7-diyl)bis(methylene))bis(oxy))diquinoline and 3,3′-(((9,9-dihexyl-9H-fluorene-2,7-diyl)bis-(methylene))bis(oxy))dipyridine were synthesized and characterized. The molecular structures of the target fluorene derivatives were well elucidated by nuclear magnetic resonance (NMR), infrared (FTIR), UV–VIS absorption and fluorescence techniques. Each of these fluorene derivatives consists of two quinoline and pyridine attached to the positions of 2 and 7 complying with C2v point group. The in-vitro cytotoxicity, antimicrobial and antioxidant activities of the title compounds were investigated. The in-vitro cytotoxicity activity of the title compounds was evaluated against human cervical (HeLa) cancer cell line wherein the IC50 values are 223.95 µg/mL and 8.34 µg/mL, respectively. Whilst the target compounds demonstrated antimicrobial activity through disc diffusion assay performed on Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Saccharomyces cerevisiae, the favourable antioxidant activities of the ultimate compounds were demonstrated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. Geometrical conformation of the above fluorene-based compounds was compared by using quantum chemical calculation in which the calculated energies of HOMO and LUMO of the compounds arising from the electron transfer were correlated with the cytotoxicity, antioxidant and antimicrobial activities.