[Fe2L3]4⁺ cylinders derived from bis(bidentate) 2-pyridyl-1,2,3-triazole "click" ligands: synthesis, structures and exploration of biological activity.

A series of metallosupramolecular [Fe2L3](BF4)4 "click" cylinders have been synthesized in excellent yields (90%-95%) from [Fe(H2O)6](BF4)2 and bis(bidentate) pyridyl-1,2,3-triazole ligands. All complexes were characterized by elemental analysis, IR, UV-vis, ¹H-, ¹³C- and DOSY-NMR spectroscopies and, in four cases, the structures confirmed by X-ray crystallography. Molecular modeling indicated that some of these "click" complexes were of similar size and shape to related biologically active pyridylimine-based iron(II) helicates and suggested that the "click" complexes may bind both duplex and triplex DNA. Cell-based agarose diffusion assays showed that the metallosupramolecular [Fe2L3](BF4)4 "click" cylinders display no antifungal activity against S. cerevisiae. This observed lack of antifungal activity appears to be due to the poor stability of the "click" complexes in DMSO and biological media.