Synthesis, crystal structure and spectral studies of silver(I) cyclohexyldiphenylphosphine complexes: towards the biological evaluation on malignant and non-malignant cells

Cancer is a fast-growing disease responsible for many deaths worldwide. Due to its aggressive and forever-changing nature, it is imperative to find alternative anti-cancer agents that could possibly treat this disease. Silver(I) phosphine complexes were synthesized by reaction of AgNO₃, AgCl, and AgBr with cyclohexyldiphenylphosphine to produce 1:1, 1:2, or 1:3 molar ratios of new silver complexes with the formulas [Ag(PPh₂Cy)NO₃] (1), [Ag(PPh₂Cy)₂NO₃] (2), [Ag(PPh₂Cy)₃NO₃] (3), [Ag(PPh₂Cy)₂Cl] (4), [Ag(PPh₂Cy)₃Cl] (5), and [Ag(PPh₂Cy)₃Br] (6), respectively. The complexes were characterized by elemental analyses, FT-IR and ¹H, ¹³C, ³¹P NMR spectroscopic techniques. The crystal structures of 5 (CCDC 1480482) and 6 (CCDC 2183297) were determined by single-crystal X-ray diffractometry. All six complexes were evaluated as potential anti-cancer agents in four different human malignant (SNO, MCF-7, A375, and A549) cell lines and one human non-malignant (HEK293) cell line. Overall, these complexes were significantly cytotoxic to both cancerous and non-cancerous cells and are therefore not considered suitable anti-cancer agents in their current form.