A first insight into the cytotoxic action mode of copper(i) iodide or copper(i) thiocyanate complexes with a phosphine derivative of sparfloxacin (a 3^rdgeneration fluoroquinolone antibiotic agent) and 2,9-dimethyl-1,10-phenanthroline or 2,2′-biquinoline as auxiliary ligands.

The new, water soluble, aminomethylphosphines were synthesized from P(CH₂OH)₃ and alkylpiperazines: P(CH₂N(CH₂CH₂)₂NCH₃)₃ (1) and P(CH₂N(CH₂CH₂)₂NCH₂CH₃)₃ (2). Described already in literature P(CH₂N(CH₂CH₂)₂O)₃ (3) were also obtained. The spectroscopic ¹H, ³¹P and ¹³C NMR analyses and crystallographic studies of 1, 2 and 3 demonstrate that all these compounds have similar structures and spectroscopic properties, which almost do not depend on aliphatic rings in the molecules. Heteroleptic copper(I) iodide complexes with phosphines mentioned above and 2,2′-bipyridine (bpy): [CuI(bpy)P(CH₂N(CH₂CH₂)₂NCH₃)₃] (1B), [CuI(bpy)P(CH₂N(CH₂CH₂)₂NCH₂CH₃)₃] (2B), [CuI(bpy)P(CH₂N(CH₂CH₂)₂O)₃] (3B) or 1,10-phenanthroline (phen): [CuI(phen)P(CH₂N(CH₂CH₂)₂NCH₃)₃] (1P), [CuI(phen)P(CH₂N(CH₂CH₂)NCH₂CH₃)₃] (2P), [CuI(phen)P(CH₂N(CH₂CH₂)₂O)₃] (3P) were also synthesized. All complexes were characterized by ¹H, ³¹P and ¹³C NMR spectroscopy also. Molecular structures of 1P·PhCH₃ and 3P·0.5Cu₂I₂(phen)₂ were determined from single crystal X-ray diffraction studies. Upon excitation at 470 nm, all complexes in the solid state exhibit red photoluminescence due to charge transfer transition. The luminescence of phen complexes is higher than the luminescence of bpy ones. The presented phosphines and copper(I) complexes were screened for their in vitro antibacterial and antifungal activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus strains and Candida albicans. All the copper complexes exhibit significant antibacterial activity against Staphylococcus aureus strains. The activity of 1,10-phenanthroline complexes is higher than 2,2′-bipyridine complexes.

In this paper we present new copper(I) iodide or copper(I) thiocyanate complexes with hydroxymethyldiphenylphosphine (PPh₂(CH₂OH)) or phosphine derivatives of sparfloxacin, a 3^rd generation fluoroquinolone antibiotic agent (PPh₂(CH₂–Sf)) and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2′-biquinoline (bq) auxiliary ligands. The synthesised complexes were fully characterised by NMR and UV-Vis spectroscopy as well as by mass spectrometry. Selected structures were additionally analysed using X-ray and DFT methods. All complexes proved to be stable in solution in the presence of water and atmospheric oxygen for several days. The cytotoxic activity of the complexes was tested against two cancer cell lines (CT26 – mouse colon carcinoma and A549 – human lung adenocarcinoma). Applying two different incubation times, the studies enabled a preliminary estimation of the dependence of the selectivity and the mechanism of action on the type of diimine and phosphine ligands. The results obtained showed that complexes with PPh₂(CH₂–Sf) are significantly more active than those with PPh₂(CH₂OH). On the other hand, the relative impact of diimine on cytotoxicity is less pronounced. However, the dmp complexes are characterised by strong inhibitory properties, while the bq ones are rather not. This confirms the interesting and promising biological properties of the investigated group of copper(I) complexes, which undoubtedly are worthy of further biological studies.