RESUMO
Indium is a nonphysiological toxic metal widely used in industry. While misunderstood, its toxicity is proposed to be linked to a perturbation of Fe3+ homeostasis through the binding of In3+ ions to essential iron metalloproteins such as transferrins. Therefore, the monitoring of In3+ and Fe3+ in biological environments is of prime interest for both basic research and diagnosis. Here we report the design of a salen-type anthracene-based probe able to selectively sense and discriminate In3+ and Fe2+/3+ ions by fluoro-colorimetry.
RESUMO
The precise arrangement of metal ions in type and number by a ligand represents an important challenge in biology as well as in materials science. The preorganization of different metal ions such as alkaline-earth and transition-metal ions is of particular interest for the design of catalysts or precursors of oxides. This study is based on a Ω-shaped salen-derived ligand comprising N2O2 and O2O2 coordination sites. The selective binding of Cu(II) and Ni(II) and alkaline-earth-metal ions is influenced by many factors such as the size of the cation, the solvent, or the counterion. UV-vis and 1H NMR titrations and single-crystal X-ray structures reveal that the obtained complexes tend to adopt different structures in solution compared to the solid state. Mainly discrete motifs with a stoichiometry 1:1 (LM1 to alkaline-earth-metal ions) have been shown to form in the solid state, whereas in solution, the 2:1 complexes are predominant.
RESUMO
It is possible to control the geometry and the composition of metallasupramolecular assemblies via the aspect ratio of their ligands. This point is demonstrated for a series of iron- and palladium-based coordination cages. Functionalized clathrochelate complexes with variable aspect ratios were used as rod-like metalloligands. A cubic Fe(II)8L12 cage was obtained from a metalloligand with an intermediate aspect ratio. By increasing the length or by decreasing the width of the ligand, the self-assembly process resulted in the clean formation of tetrahedral Fe(II)4L6 cages instead of cubic cages. In a related fashion, it was possible to control the geometry of Pd(II)-based coordination cages. A metalloligand with a large aspect ratio gave an entropically favored tetrahedral Pd(II)4L8 assembly, whereas an octahedral Pd(II)6L12 cage was formed with a ligand of the same length but with an increased width. The aspect ratio can also be used to control the composition of dynamic mixtures of Pd(II) cages. Out of two metalloligands with only marginally different aspect ratios, one gave rise to a self-sorted collection of Pd(II)4L8 and Pd(II)6L12 cages, whereas the other did not.
