Anion receptors, supramolecular organic

Reviews Dietrich, B. (1993) Design of anion receptors Applications, Ptire and Appl. Chem. 65, 1457 Bianchi, A., Bowman-James, K. and Garcia-Espana, E. (1997) Supramolecular Chemistry of Anions, Wiley-VCH, New York Schmidtchen, F. P. and Berger, M. (1997) Artificial Organic Host Molecules for Anions, Chem. Rev. 97,1609-1646. 

It is the intention of this chapter to present an overview of the potential of the extraction technique for characterizing the binding strengths, selectivity, speciation and phase transfer behavior of supramolecular receptors towards selected cations, anions, salts and zwitterions in aqueous-organic, two-phase systems. The role of... 

A number of other metal-based redox-active centers have been incorporated into supramolecular receptors, representative examples of which are displayed in Fig. 5 (Compounds 24-28). Many of these receptors electro-chemically respond to cations. but species that respond to anions and neutral molecules are also known. A number of the cation binders are organometallic crown ether and metallocrown or metallothiacrown derivatives, for example. Compound 24. Flow-ever, in many cases, the redox processes are not particularly reversible, and relatively small anodic shifts in the metal-centered redox couples are observed. A series of self-assembled [12]metallocrown-3 complexes, two of which are 25 and 26, were found by Severin to bind halide salts of small Group 1 metals strongly in organic solvents, with affinities similar to those of the cryptands. X-ray crystal structures revealed that the metal cation was... 

From a supramolecular point of view, anionic species play a key role in many mineral or biological routes. Despite this, however, anion-centered self-assembly processes were little explored. Recently, anion coordination was addressed mainly through the design of e z/q-receptors on the contrary, the electron-poor organic halides work effectively as ew-receptors of anions. The ability described here of the halide anions to act as electron donors to carbon-bound halogens may develop as a general protocol for halide-centered supramolecular chemistry. 

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