Imidazo-pyridine-based zinc(II) complexes as fluorescent hydrogen sulfide probes.

In this work we explore the interaction of HS with a family of fluorescent zinc complexes. In particular we selected a family of complexes with N,O-bidentate ligands aiming at assessing whether the zinc-chelating ligand plays a role in influencing the reactivity of HS with the complexes under investigation. Different experiments, performed by diverse spectroscopic techniques, provide evidence that HS binds the zinc center of all the complexes included in this study. The results highlight the potential of the devised systems to be used as HS/HS fluorescent sensors a coordinative-based approach. To shed light on the species formed in solution when HS/HS interacts with the title complexes and aiming to rationalize the photophysical properties of the sensing constructs, we performed a computational analysis based on the time dependent density functional theory (TD-DFT). Preliminary bio-imaging experiments were also performed and the results indicate the potential of this class of compounds as probes for the detection of HS in living cells.