Tripodal receptor

The reaction of carboxycobalticinium hexafluorophosphate (88) with AMiydroxysuccinimide gave the activated ester (89) in excellent yield. Condensation of 3 mol of (89) with 1,3,5-triaminomethylbenzene and tris(2-aminoethyl)amine in the presence of triethylamine gave, respectively, the new acyclic tripodal receptors (90) and (91) in 65 and 60% yields (Scheme 29). 

Figure 15. Schematics of tripodal receptors for halide ions.

A homochiral tripodal receptor with selectivity for sodium (R)-2-aminopropionate over sodium (5)-2-aminopropionate, J. Howarth and N. A. Al-Hashimy, Tetrahedron Lett., 2001, 42, 5777. 

Figure 9. Optimized structure (B3LYP/6-31G ) of a complex of acetylcholine and a benzene based tripodal receptor with pyrrole arms.

As can be noticed, most of oiu" previous discussion featured the benzene-based tripodal receptors. The fact that a single receptor with suitable substituents can exhibit affinity and selectivity for both cations and anions (amphi-ionophores), led us to theoretically investigate the possibility of other systems possessing similar characteristics [36,41]. 

FIGURE 115 Synthesis of the inert HHH-[Ru(LJ6)3] tripodal receptor and of its triple-stranded d-f HHH-[RuLu(L36)3] + and HHH-[RuCa(LJ6)3] helicates (adapted from Canard and Piguet, 2007). 

The tripodal receptor containing three ferrocene units and four nitrogen atoms, 68, selectively forms a host-guest complex with the H2P04 anion and electro-... 

Tripodal receptors based on an arene core have proved particularly popular, in part due to the degree of preorganization afforded by steric hindrance around the arene core. Early work by Lehn s group showed that the tripodal receptor 26 in conjunction with planar ligand 27 gives a discrete capped trinuclear complex on reaction with copper(I). ... 

Rigault S., C. Piguet, G. BemardineUi, G. Hopfgartner, Lanthanide-Assisted Self-Assembly of an Inert, Metal-Containing Nonadentate Tripodal Receptor. Angew. Chem. Int. Ed. 37, 169—172... 

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