Colorimetric detection of Cu[II] cation and acetate, benzoate, and cyanide anions by cooperative receptor binding in new α,α′-bis-substituted donor-acceptor ferrocene sensors

New ferrocene derivatives bearing two donor-acceptor systems are capable of selectively sensing cations and anions by cooperative binding of the two alpha,alpha'-groups bonded to the ferrocene nucleus, thus permitting the naked-eye selective colorimetric detection of copper[II] cation and acetate, benzoate, or cyanide anions, which are ions of toxicological and biological relevance.