Anthraquinone-1,8-Derived (Pseudo-) Crown and Lariat Ethers:Design and Applications as Fluorescent and Chromogenic Ion (Pair) Sensors

Cyclic polyamine/ethers embedded with anthraquinone moieties and functional pendants, are structural analogues of crown ethers and (oxo-) cyclams, and could be utilized as sensitive and selective chemosensors towards metal cations. Those pseudo- (similar but geometrically distinct) crown and lariat ethers show various cation-binding patterns and stoichiometry, being modulated by donor type, cavity size and pendants' chelating ability. The luminescent and chromogenic properties also differ a lot along with the derivation of the parental macrocycle. Methodological designing including synthesis and post-functionalization through nucleophilic substitution, Mannich condensation etc., as well as the sensing performance of those pseudo-crown and lariat ethers are summarized in this review, basing on the spectroscopic, voltammetric and X-ray crystallographic determinations. Anion effect in sensing cations is evaluated according to the ion-pair recognition theory. Those results shed some light on exemplifying the anions' role in bioinorganic systems including metalloenzymes.