Switching the Recognition Preference of Rhodamine B Spirolactam by Replacing One Atom: Design of Rhodamine B Thiohydrazide for Recognition of Hg(II) in Aqueous Solution

Abstract

A new chemosensor based on rhodamine B thiohydrazide is described. Chemosensor B was found to show a reversible dual chromo- and fluorogenic response toward Hg²⁺ in aqueous solution in a highly selective and sensitive manner. This was suggested to result from the coordination of Hg²⁺ at the N, S binding sites in B to open its spiro ring.