A series of five zinc(II) complexes containing two 4(1H)-quinolinone-based ligands (Hqui), with the composition of Zn(H2O)(qui)2 (1–5), was prepared and characterised. The X-ray structure of complex (3·3EtOH) revealed a distorted square-pyramidal geometry with the O5 donor set, originating from two bidentate-coordinated qui ligands and a coordinated water molecule. Hirshfeld surface analysis showed that the crystal structure is primarily stabilised by O–H···O and N–H···O hydrogen bonds, supported by C–H···O and C–H···Cl contacts, and distinct π–π stacking between quinolinone units. The shape-index and curvedness maps indicated π–π stacking and planar packing features, whilst the fingerprint plots revealed H···H, H···C/C···H, and H···O/O···H contacts as the main contributors to the intermolecular landscape, emphasising the roles of hydrogen bonding and dispersion forces in stabilising the crystal packing. The complexes were tested for their in vitro antitumour activity on human osteosarcoma (HOS), breast adenocarcinoma (MCF7), ovarian carcinoma (A2780), androgen-sensitive prostate adenocarcinoma (LNCaP), and Caucasian prostate adenocarcinoma (PC3) cancer cell lines. The limited solubility of the complexes in cell culture media prevented cytotoxicity testing at concentrations above 10 µM (or above 20 µM), and unfortunately, the exact IC50 values could not be determined under these conditions, although a decrease in cancer cell viability with increasing concentrations of the complexes was observed in some cases.
Trávnı́ček et al. (Wed,) studied this question.