Synthesis, crystal structure and in vitro antifungal activity of two-dimensional silver(I)-voriconazole coordination complexes

Two silver(I)-voriconazole (Vor) coordination complexes, namely [Ag(Vor)2]n(ClO4)n (1) and [Ag2(Vor)4]n(NO3)2n (2), were synthesized and structurally characterized by X-ray single-crystal and powder diffraction, 1H nuclear magnetic resonance, and infrared spectra. Both complexes featured an equimolar stoichiometry between Ag(I) ion and Vor within 2-D layer-like arrays, in which voriconazole exhibited unique and different coordination modes (mono-/tri-dentate modes in 1 and mono-/bi-/tri-dentate modes in 2). The perchlorate and nitrate anions were embedded in the two-dimensional plane. The results of antifungal studies demonstrated that both complexes possessed higher activity against voriconazole-resistant fungi than voriconazole alone, which might be caused by inhibiting the efflux pump activity of resistant fungi. Additionally, both silver(I) complexes showed no significant cytotoxicity on HaCaT cells in the MIC90 range for 24 h. These studies suggested that silver(I)-voriconazole coordination complexes were promising candidates as antifungal agents to resistant fungi.