Synergistic actions between tebuconazole ligand and Cu(ii) cation: reasons for the enhanced antifungal activity of four Cu(ii) complexes based on the fungicide tebuconazole

Abstract

Four Cu(II) complexes, namely, [CuL₂(SO₄)(DMF)]_n1, [CuL₂(CH₃COO)₂] 2, [CuL₄Cl₂]·2DMF·3H₂O 3 and [CuL₄(ClO₄)₂] 4, (L = ((RS)-1-(4-chloro-phenyl)-4,4-dimethyl-3-(1,2,4-triazole-1-ylmethyl)pentan-3-ol), tebuconazole) have been synthesized and their structures were identified by elemental analysis (EA), infrared (IR) spectroscopy and single crystal X-ray diffraction (XRD). Moreover, the four obtained complexes were screened for antifungal activities against four selected fungi using the mycelial growth rate method. Structural analysis indicates that the different coordination modes of the ligands and counter anions contribute to a one-dimensional polymer chain structure in complex 1 and zero-dimensional mononuclear structures in complexes 2–4. The results of the antifungal activities show that all the complexes synthesized show better antifungal activities than the ligand L. In addition, the mechanism of the increased antifungal activities of the title complexes in comparison with the ligand was discussed preliminarily and the synergistic interaction between Cu²⁺ and tebuconazole was also investigated by the Wadley approach.