Azadithiacrown ether based ditopic receptors capable of simultaneous multi-ionic recognition of Ag+ and Hg2+

Novel azadithiacrown ether containing bis(styryl)pyridinium dyes were synthesized and their complexation with different transition metal cations was investigated. It was found that the compounds give a selective ratiometric optical response in the presence of silver (I) and mercury (II) cations. Evidence was given for the occurrence of two stoichiometries: LM and LM2. Moreover, the formation of a mixed complex [Ag+·L·Hg2+] containing both Ag+ and Hg2+ cations simultaneously was demonstrated. Optical spectroscopy was used to estimate stability constant values of the complexes, NMR spectroscopy data allowed us to offer a model of spatial arrangement of the obtained species.

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► Novel bis(styryl)pyridinium dyes containing two azadithiacrown receptors were synthesized.
► Complexation with transition metal ions were investigated by optical and NMR spectroscopy.
► Evidence was given for the occurrence of mono- and bimetallic complexes.
► The formation of a mixed heterometallic complex with both Ag+ and Hg2+ ions was studied.
► Being absorbed onto the solid surface the dyes retain their cation binding properties.