Template-assembled tripodal

Research by P. Scrimin and U. Toneiiato et ai. showed that Zn " was an aiiosteric reguiator of liposomal membrane permeability induced by synthetic template-assembled tripodal polypeptides. Several copies of peptide sequences from the peptaibol family were connected to fr/s(2-aminoethyl)amine (TREN), which is a tripodal metal ion ligand. The resulting tripodal polypeptides were capable of modifying the permeability of liposomal membranes, and their activity was tunable upon metal ion coordination of the TREN subunit. The synthesis of the TREN-based template began with the Stephen reduction of 4-cyanomethylbenzoate followed by the reductive amination of the resulting aldehyde with TREN. 

Scrimin, P., Tecilla, P., Tonellato, U., Veronese, A., Crisma, M., Formaggio, F., Toniolo, C. Zinc(ll) as an allosteric regulator of liposomal membrane permeability induced by synthetic template-assembled tripodal polypeptides. Chem.-Eur. J. 2002, 8, 2753-2763. 

When triethanolamine H3L13 (35) was reacted with sodium hydride and iron(III) chloride, the hexanuclear centrosymmetric ferric wheel [Nac Fe6(L13)6 )Cl (36) was isolated. Amidst a set of possibilities in the template-mediated self-assembly of a supramolecular system, the one combination of building blocks is realized that leads to the best receptor for the substrate [112]. Therefore, the six-membered cyclic structure 36 is exclusively selected from all the possible iron triethoxyamine oligomers, when sodium ions are present. The iron(III) complex 36 is present as an Sg-symmetric wheel, with an encapsulated sodium ion in the center and a chloride counterion. Consequently, the trianion (L13)3- acts as a tripodal, tetradentate, tetratopic ligand, which each links three iron(III) ions and one sodium ion. In the presence of cations with different ionic radii, different structures are expected. Therefore, when triethanolamine H3L13 (35) was reacted with cesium carbonate and iron(III) chloride, the octanuclear centrosymmetric ferric wheel [Csc Fe8(L13)8 ]Cl (37) was isolated (Scheme 13) [113]. 

In another example of, this time a polymeric, MOF system, Custelcean, Moyer, and Hay reported an extended silver-based MOF that binds sulfate. They used the labile silver(I) d salt, Ag2S04, as a template in the assembly of two tripodal Iren-based urea hosts functionalized with... 

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