Effect of the complex-formation ability of thiosemicarbazones containing (aza)benzene or 3-nitro-1,8-naphthalimide unit towards Cu(II) and Fe(III) ions on their anticancer activity

[Display omitted] •The properties of thiosemicarbazones with (aza)benzene and 3-nitro-1,8-naphthalimide fragments were compared.•Anticancer activity and chelating behavior (Cu, Fe) of TSCs were tested.•Spectroscopic analysis allows to localize chelating site of TSCs.•Chelating behavior (Cu, Fe) of tested TSCs correlates with anticancer activity. We recently described a novel class of thiosemicarbazones (TSCs) with a high anticancer activity. Now, we expanded this compound library with a new class of TSCs with a 3-nitro-1,8-naphthalene unit. Thus, a series of novel TSC conjugates was obtained to determine the effect of its chemical structure on spectroscopic properties, metal complexing and biological activity. They were prepared in a microwave reactor, provided compounds with both a high yield and purity. Nuclear magnetic resonance (1H and 13C NMR, COSY, HMQC) and infrared spectroscopy were used to characterize them structurally. Additionally, DFT calculations were performed in order to obtain the optimized ground-state geometry. Physicochemical spectroscopic studies were conducted in different solvents and conditions to assess the effect of the substituent on the optical properties and metal complexing ability. The anticancer activity was tested on three cancer cell lines and then correlated with the spectroscopic results. Here, we show based on in vitro chelating studies, that anticancer activity is closely correlated with the Fe3+ and Cu2+ chelating ability of these compounds.