Tethering (Arene)Ru(II) Acylpyrazolones Decorated with Long Aliphatic Chains to Polystyrene Surfaces Provides Potent Antibacterial Plastics

The acylpyrazolone proligands HQR (HQR in general, in detail: HQCy = 1-phenyl-3-methyl-4-carbonylcyclohexyl-5-pyrazolone, 4-C(O)-phenyl, HQPh = 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, HQC17 = 1-phenyl-3-methyl-4-stearoyl-5-pyrazolone, HQC17,Ph = 1-phenyl-3-stearyl-4-benzoyl-5-pyrazolone) were synthesized and reacted with (arene)Ru(II) acceptors affording complexes [(arene)Ru(QR)Cl] (arene = cymene (cym) or hexamethylbenzene (hmb)). The complexes were characterized by elemental analyses, thermogravimetric analysis-Differntial Thermal Analysis (TGA-DTA), IR spectroscopy, ESI-MS and 1H, and 13C NMR spectroscopy. Complexes [(arene)Ru(QR)Cl] where QR = QC17 and QC17,Ph, due to the long aliphatic chain in the ligand, afford nanometric dispersions in methanol via self-assembly into micellar aggregates of dimensions 50–200 nm. The antibacterial activity of the complexes was established against Escherichia coli and Staphylococcus aureus, those containing the ligands with a long aliphatic chain being the most effective. The complexes were immobilized on polystyrene by a simple procedure, and the resulting composite materials showed to be very effective against E. coli and S. aureus.