The ruthenium unit was introduced into the redox-active molecular poly gon to assembly new Ru-Fc metallocycles (Compound 1), in which the redox active (ferrocene) and fluoresecent (ruthenium) signaling subunits are directly attache d by the putative cation-binding sites. The compound 1 displayed high selectivit y for Ca2+ by electrochemical tests. The measurements of the fluorescence spectr a on titration of 1 with Ca2+, Li+, Na+, K+, Mg2+ or Ba2+ ion indicate the uniqu e ability of 1 to detect Ca2+ ions selectively.
