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When the redox-switchable ionophores switch between their oxidized and reduced forms, they demonstrate different ligating abilities in these forms. The redoxswitchable naphthaquinone-derived ionophores (D1-D5) are designed and synthesized in this study, with the aim of investigating their cation transport abilities and selectivities across a bulk liquid membrane (BLM) transport system. The biologically significant cations include Li+, Na+, K+, Ca2+, and Mg2+. The selectivity trend shown by D1, D3, D3a, and D5 is expressed as Mg2+ >> Na+ > K+ ≈ Ca2+, whereas that of D2, D4, and D4a is given by Mg2+ >> Na+ > Ca2+ ≈ K+. The selective transport of Mg2+ over Li+, Na+, K+, and the ionophores is also observed. The presence of quinone redox moiety in the ionophores leads to their enhanced carrier ability in a reduced state. Ultimately, any variation in the topology of the ionophores lead to variations in their cation-binding strengths and selectivities. The intrinsic abilities of these ionophores to selectively bind and transport Mg2+ is demonstrated. Moreover, the good and selective transport of Mg2+ by D1 reveals its scope in molecular devices, whereas the poor but selective transport of Mg2+ by D4a and D5 demonstrate their application in sensors. l [ABSTRACT FROM AUTHOR]

Redox switched anthraquinone derived podands 1-(anthra­quinonyloxy), 3 methoxy methane (T1) and 1,5 bis-(2-(2-hydroxyethoxy)ethoxy)anthracene-9-10-dione (T2) have been synthesized by condensation of 1-chloroanthraquinone, 1,5-dichloro-anthraquinone with methoxy methanol and diethylene glycol in THF under N2 atmosphere characterized by m.p., TLC and IR, NMR, Mass analysis. Extraction and transport of metal ions in oxidized and reduced state is Ca2+>K+>Li+, Li+>K+>Ca2+. The results of the transport study reveal that ionophore T1 and T2 are selective for Ca2+; this selectivity can be used for fabrication of ion selective electrodes and sensors. Double-armed ionophore T2 is a good extractant and is transporter for metal ions compared to single-armed podands. Extraction and transport ability enhanced in reduced state. [ABSTRACT FROM AUTHOR]