Spectroscopic characterization of Lanthanoid derived from a hexadentate macrocyclic ligand: Study on antifungal capacity of complexes

•A hexadentate macrocyclic ligand i.e. 3,5,13,15,21,22-hexaaza-2,6,12,16-tetramethyl-4,14-dithia-tricyclo[15.3.1.1(7-11)]docosane-1(21),2,5,7,9,11(22),12,15,17,19-decaene was synthesized and characterized.•Lanthanoid complexes were synthesized and characterized using various spectral techniques.•Spectral parameters suggested formation of metal ligand covalent bonding.•The complexes were found to have coordination number nine.•In vitro antifungal capacity was determined of the synthesized compounds.

Complexes of Ce(III), Nd(III), Sm(III) and Eu(III) were synthesized with NO-donor macrocyclic ligand, i.e. 3,5,13,15,21,22-hexaaza-2,6,12,16-tetramethyl-4,14-dithia-tricyclo[15.3.1.1(7-11)]docosane-1(21),2,5,7,9,11(22),12,15,17,19-decaene. The ligand was obtained by the condensation of 2,6-diacetylpyridine with thiourea and characterized by elemental analysis, mass, IR and 1H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinated through four nitrogen atoms of azomethine groups and two nitrogen atoms of pyridine ring. The value of spectral parameters i.e. nephelauxetic effect (b), covalency factor (b1/2), Sinha parameter (δ%) and covalency angular overlap parameter (η) account for the covalent nature of the complexes. The macrocyclic ligand and its Lanthanoid were tested in vitro against two plant pathogenic fungi in order to assess their antifungal capacity.

Graphical abstractGrowth inhibition of synthesized compounds against Fusarium oxysporum.Figure optionsDownload full-size imageDownload as PowerPoint slide