Cu(II)- and Hg(II)-induced modulation of the fluorescence behavior of a redox-active sensor molecule.

Here, we report on a fluorescent 1,2,4-thiadiazole derivative (oxidized form) and its reduced form, the corresponding iminoyl thiourea. The thiadiazole displays a strong modulation of its fluorescence behavior, selectively upon addition of Cu(II), while the iminoyl thiourea functions as a chemodosimeter for Hg(II). Additionally, the Cu(II)-thiadiazole complex is characterized by HRMS, and the Hg(II)-induced desulfurization of the iminoyl thiourea is monitored by mass spectrometry.