A bis-guanidine-based multisignaling sensor molecule that displays redox-ratiometric behavior or fluorescence enhancement in the presence of anions and cations

structure: see text]The guanidine bridge in the new structural motif 3,3]ferrocenophane acts as a dual binding site for anions and metal ions. Sensing of anions (Cl(-), F(-), NO(3)(-), HSO(4)(-), and H(2)PO(4)(-)) takes place by redox-ratiometric measurements, whereas metal ion (Zn(2+), Ni(2+), and Cd(2+)) recognition is achieved by fluorescence measurements.