Synthesis, characterization, thermal behavior, and antifungal activity of La(III) complexes with cinnamates and 4-methoxyphenylacetate

In this study a series of trivalent lanthanum complexes with 4-(R)-cinnamate (4-Rcinn, R=H(1), MeO(2), Cl(3)) and 4-methoxyphenylacetate ligands (4) were prepared and their antifungal activity against Candida albicans, Aspergillus niger and Trichophyton mentagrophytes were examined. Compounds 1–4 were synthesized by a metathesis reaction and fully characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, fluorescence spectra, thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC) and X-ray diffraction powder patterns. In emission studies, it was observed that luminescence intensity was enhanced in the presence of lanthanide ion. The results of X-ray diffraction patterns indicated that all complexes studied exhibited crystalline structure. Thermal behavior by TG, DTG, and DSC studies permitted to estimating the hydration degree of the compounds and showed the formation of decomposition products like lanthanum oxide. Determined by antifungal studies, lanthanum complexes 1–4 demonstrated antifungal activity toward all pathogenic fungal strains tested. Compounds 2 and 4 showed significant growth inhibition for A. niger and C. albicans, respectively.

Graphical abstractSuggested structure and simultaneous TG-DTG curves of lanthanum (III) complexFigure optionsDownload full-size imageDownload as PowerPoint slide