Anthracene-Containing Podands, Ion-Active Molecular Switches of Fluorescence Characteristics

Abstract

2,2′-[Ethane-1,2-diylbis(oxy)]bis[N-(anthracen-9-ylmethyl)ethanamine] and its bisphenylthiourea and bisthiourea derivatives have been synthesized. The diamine, being a certain analog of an aza-crown ether with an open chain, exhibits a 50 times increase in the relative fluorescence intensity (off-on process) in the presence of cadmium(II) cations. Bis(phenylthiourea) is a bifunctional fluorophore sensitive to mercury(II) cations (emission flaring) and fluoride anions (emission quenching). Anions F^–, CN^–, H₂PO₄^–, and AcO^– lead to a practically complete quenching of the fluorescent properties of the bis(thiourea) (off-on process).