Copper(i) iodide complexes containing new aliphatic aminophosphine ligands and diimines—luminescent properties and antibacterial activity

Abstract

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.