Novel Lanthanide Complexes of Ciprofloxacin_: Synthesis, Characterization, Crystal Structure and in vitro Antibacterial Activity Studies

Novel lanthanide coordination compounds with ciprofloxacin (CPFX), including eleven complexes Ln(CPFX)₂Cl(H₂O), (Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; n = 7, 8, 9) and crystalline [Ce(CPFX)₂ (H₂O)₄] Cl (H₂O)_3.25 (C₂H₅-OH)_0.25, were synthesized. The crystal is of triclinic space group Pi with a= 1.3865(2) nm, b = 1.3899(3) nm, c = 1.6505(2) nm, a = 92.73(1)°, β= 114.39(1)°, γ=115.55 (1)°, Z = 2 and R = 0.0449. FT-IR, electronic spectroscopy and X-ray diffraction were employed to show that the lanthanide ion, which displays an eight-coordinate structure, is chelated by 3-carboxyl and 4-keto oxygen donors of CPFX and two six-membered chelate rings are formed. Test of in vitro antibacterial activity against E. coli, P. aeruginosa and S. aureus indicated that the in vitro antibacterial activity of the ligand can be improved by complexation with Ce(III).