Fluorescent salen-type Zn(II) Complexes As Probes for Detecting Hydrogen Sulfide and Its Anion: Bioimaging Applications

In this work, we investigate the mode of interaction of a family of fluorescent zinc complexes with HS– and H2S. Different experiments, performed by diverse spectroscopic techniques, provide evidence that HS– binds the zinc center of all the complexes under investigation. Treatment with neutral H2S exhibits a markedly different reactivity which indicates selectivity for HS– over H2S of the systems under investigation. Striking color changes, visible to the naked eye, occur when treating the systems with HS– or by an H2S flow. Accordingly, also the fluorescence is modulated by the presence of HS–, with the possible formation of multiple adducts. The results highlight the potential of the devised systems to be implemented as HS–/H2S colorimetric and fluorescent sensors. Bioimaging experiments indicate the potential of using this class of compounds as probes for the detection of H2S in living cells.