Masked Amino Trimethyl Lock (H(2)N‐TML) Systems: New Molecular Entities for the Development of Turn‐On Fluorophores and Their Application in Hydrogen Sulfide (H(2)S) Imaging in Human Cells

Masked trimethyl lock (TML) systems as molecular moieties enabling the bioresponsive release of compounds or dyes in a controlled temporal and spatial manner have been widely applied for the development of drug conjugates, prodrugs or molecular imaging tools. Herein, we report the development of a novel amino trimethyl lock (H(2)N‐TML) system as an auto‐immolative molecular entity for the release of fluorophores. We designed Cou‐TML‐N(3) and MURh‐TML‐N(3) , two azide‐masked turn‐on fluorophores. The latter was demonstrated to selectively release fluorescent MURh in the presence of physiological concentrations of the redox‐signaling molecule H(2)S in vitro and was successfully applied to image H(2)S in human cells