[Fe2L3]4+ Cylinders Derived from Bis(bidentate) 2-Pyridyl-1,2,3-triazole “Click” Ligands: Synthesis, Structures and Exploration of Biological Activity

Abstract

A series of metallosupramolecular [Fe 2 L 3 ](BF 4 ) 4 "click" cylinders have been synthesized in excellent yields (90%-95%) from [Fe(H 2 O) 6 ](BF 4 ) 2 and bis(bidentate) pyridyl-1,2,3-triazole ligands. All complexes were characterized by elemental analysis, IR, UV-vis, 1 H-, 13 C-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 [Fe 2 L 3 ](BF 4 ) 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.

Synthesis, structure, stability and antimicrobial activity of a ruthenium(II) helicate derived from a bis-bidentate “click” pyridyl-1,2,3-triazole ligand

“…Additionally, the spectrum of 2a is very similar to the previously reported iron(II) analogue (Fig. 1c) [51,57]. Further support for the formation of the ruthenium(II) helicate was obtained from 1 H DOSY NMR spectroscopy (Supporting information).…”

“…We [39][40][41][42][43][44] and others [45][46][47][48][49][50][51][52][53][54][55] have explored the use of 1,4-disubstituted 1,2,3-triazole containing ''click'' ligands in the development of functionalized metallosupramolecular architectures and have shown that metallomacrocycles, cages and helicates can be readily generated. As part of that work we developed a small family of bis-2-(1-R-1H-1,2,3-triazol-4-yl)pyridine ligands 1 [56] (Scheme 1) and showed that they would assemble into [Fe 2 L 3 ] 4+ metallosupramolecular helicates [57] when treated with Fe(II) ions. Molecular modeling indicated that some of these ''click'' complexes were of similar size and shape to the biologically active pyridylimine-based iron(II) helicates and suggested that the ''click'' complexes may bind to both duplex and triplex DNA.…”

Oxidatively Locked [Co2L3]6+ Cylinders Derived from Bis(bidentate) 2-Pyridyl-1,2,3-triazole “Click” Ligands: Synthesis, Stability, and Antimicrobial Studies

“…In order to gain some structural information on the cobalt(III) cylinders derived from L1 and L2, we synthesised the related iron(II) complex Unfortunately, despite extensive efforts, crystals of the cobalt(III) cylinders of the quality required for X-ray diffraction (XRD) studies could not be obtained [51]. The analogous [Fe 2 L3 3 ](BF 4 ) 4 , and [Ru 2 L3 3 ](PF 6 ) 4 cylinders have been previously crystallographically characterised and were found, in both cases, to be racemic mixtures of the ∆∆ and ΛΛ helicates [30,32,33]. In order to gain some structural information on the cobalt(III) cylinders derived from L1 and L2, we synthesised the related iron(II) complex [ (Figure 1b and Supplementary Materials, Figure S30).…”

“…These "click" ligands have been exploited for a range of purposes including the construction of metallosupramolecular macrocycles [26][27][28][29] and helicates [30,31]. In a previous work, we have exploited "click" ligands to synthesise triply [32,33] and quadruply [34] stranded helicates and explored the biological activity of these systems. We showed that a dipalladium quadruply stranded helicate had good cytotoxicity (IC 50 = 3-7 µM) against three different cancer cell lines; however, disappointingly, the complex displayed no selectivity towards non-cancerous phenotypes.…”

“…We showed that a dipalladium quadruply stranded helicate had good cytotoxicity (IC 50 = 3-7 µM) against three different cancer cell lines; however, disappointingly, the complex displayed no selectivity towards non-cancerous phenotypes. Inspired by the iron(II) systems developed by Hannon and Scott, we used L3 (Scheme 1) and some other related bis(bidentate) 2-pyridyl-1,2,3-triazole "click" ligands (L pytrz ) to synthesise a small family of iron(II) cylinders [Fe 2 (L pytrz ) 3 ] 4+ [32]. Unfortunately, these [Fe 2 (L pytrz ) 3 ] 4+ cylinders displayed no biological activity (against the yeast Saccharomyces cerevisiae).…”