Entasis through hook-and-loop fastening in a glycoligand with cumulative weak forces stabilizing Cu(I).

The idea of a possible control of metal ion properties by constraining the coordination sphere geometry was introduced by Vallee and Williams with the concept of entasis, which is frequently postulated to be at stake in metallobiomolecules. However, the interactions controlling the geometry at metal centers remain often elusive. In this study, the coordination properties toward copper ions—Cu(II) or Cu(I)—of a geometrically constrained glycoligand centered on a sugar scaffold were compared with those of an analogous ligand built on an unconstrained alkyl chain.

Apo-neocarzinostatin: a protein carrier for Cu(II) glycocomplexes and Cu(II) into U937 and HT29 cell lines.

In the field of pharmaceuticals there is an increasing need for new delivery systems to overcome the issues of solubility, penetration, toxicity and drug resistance. One of the possible strategies is to use biocarriers such as proteins to encourage the cell-penetration of drugs. In this paper, the use of the apo-protein neocarzinostatin (apo-NCS) as a carrier-protein for two Cu(II) glycocomplexes, previously characterized, and Cu(II) ions was investigated.

Intrinsically fluorescent glycoligands to study metal selectivity.

Glycoligands are a versatile family of ligands centered on a sugar platform and functionalized by Lewis bases. In this article, pentofuranoses were appended with the fluoroionophores 4-(pyridin-2'-yl)-1,2,3-triazol-1-yl and 4-(2',1',3'-benzothiadiazol-4'-yl)-1,2,3-triazol-1-yl using the "click-like" cycloaddition [2 + 3] of Huisgen catalyzed by copper(I). Their fluorescence properties were used to study metal cation complexation.

Sugars to control ligand shape in metal complexes: conformationally constrained glycoligands with a predetermination of stereochemistry and a structural control.

In coordination chemistry, ligand shape can be used to tune properties, such as metal selectivity, coordination number, electronic structure, redox potential, and metal center stereochemistry including coordination helicates formation, and also to generate cavities for encapsulation. The results presented in this article indicate that two epimeric glycoligands (3 and 4) based on the conformationally restrained xylo- and ribo-1,2-O-isopropylidenefurano scaffolds are preorganized in water through pi-pi stacking due to hydrophobic interactions, as evidenced from excimer observation. The structure obtained in the solid state for one of the Cu(II) complexes (5) is chiral, with an original helical chirality arising from the coiling of the two ligands around the Cu-Cu axis.

Synthesis of propargylic fluorides from allenylsilanes.

Allenylsilanes reacted at room temperature in acetonitrile with Selectfluor, an electrophilic fluorinating reagent, to give secondary propargylic fluorides in moderate to good yields; mechanistically, a side-product resulting from a 1,2-silyl shift testifies to the presence of a cationic intermediate.