Chemosensing ensemble

Fabbrizzi L, Leone A, Taglietti A (2001) A chemosensing ensemble for selective carbonate detection in water based on metal-ligand interactions. Angew Chem Int Ed 40 3066-3069... 

Titration of the resulting cheinosensing ensemble solution with a standard solution of carbonate (Fig. 7, full triangles) results in an almost complete recovery of the coumarine emission. This result indicates that there is successful competitive binding of the HCO ions and displacement of the indicator from the intermetallic cavity of complex 8. Full restoration of the coumarine emission is also observed when the solution of the chemosensing ensemble is titrated with and with... 

Other approaches than the luminophore-spacer-receptor paradigm exist, illustrated in the preceding examples, for designing a molecular system for sensing analytes in solution. An efficient one—the chemosensing ensemble approach—is reminiscent of the antibody-based competition test in immunoassays. According to this approach. 

Fig. 7 Titration of the chemosensing ensemble [8 + 9] with some inorganic anions. HCO3 is able to displace the indicator from cape 8. an event signaled by fluorescence revival of the released indicator 9 (full triangles). Other anions do not displace the indicator and do not make fluorescence revive phosphate (open triangles) acetate (full circles) and sulfate (open diamonds).

Fig. PO The chemosensing ensemble paradigm. A fluorescent indicator occupies the cavity of a receptor, and its emission is quenched. When displaced by an analyte showing a higher affinity for the receptor, it displays its full fluorescence, so signaling the occun ence of analyte recognition.

Such a line defines the anions that can be revealed through the chemosensing ensemble procedure, by using coumarine 343 as an indicator. In particular, those anions with logK values that stay above the dashed line are able to displace the indicator from the cage and can be fluorimetrically detected. On the other hand, anions with logA" values that stay below the dashed line are not able to displace the indicator from the host cavity and cannot be fluorimetrically detected. 

J. J. Lavigne, E. V. Anslyn, Teaching old indicators new tricks a colorimetric chemosensing ensemble for tartrate/malate in beverages, Angewandte Chemie-lnternational Edition 1999, 38, 3666. 

Figure 14 Calibration curves for various amino acids using chemosensing ensemble composed of 24 and coumarin (a), fluorescein (b), and eosine Y (c). Histidine ( ), glycine (A), alanine ( ), and phenylalanine (O). (Reproduced from Ref. 35. American Chemical Society, 2003.)...

Figure 33 Schematic illustration of the proposed chemosensing ensemble. (Reproduced from Ref. 74. American Chemical Society, 2009.)...

A competitive assay (indicator displacement assay, IDA) was reported by Anslyn using the Zn(II) complex 49 shown in Figure 21. This 2,2 6,2"-terpyridine complex forms a chemosensing ensemble with pyrocatechol violet because of the ability of the dye to chelate the Zn(II) cation. On addition of a series of unprotected amino acids to a solution of the chemosensing ensemble, the release of the dye was visually verified and spectroscopically measured (1 1... 

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