New Fluorescent Chemodosimetric Mechanism for Selective Recognition of Selenocysteine by Dansyl-Appended Ruthenium Nitrosyl Complexes.

Selenocysteine (Sec) is a biologically essential amino acid that serves as a crucial component in selenoproteins that play a key role in various cellular functions. Thus, developing a reliable and rapid method for detecting Sec in physiological media is of paramount importance. This report introduces for the first time a novel fluorescent chemodosimetric mechanism for the selective recognition of Sec using dansyl-appended ruthenium nitrosyl complexes. These complexes consist of a tetradentate ligand featuring a π-extended system ( = ,'-bis(2-hydroxy-1-naphthylidene)-1,2-phenylenediamine) and a monodentate ligand derived from the conjugated dansyl group, which acts as a strong fluorescent signaling unit ( = dansyl-imidazole, = dansyl-benzimidazole). The reaction between Sec and the complexes {RuNO} = or in an aqueous phase enhances fluorescence; as a result, it releases NO that has been demonstrated through fluorimetric titrations, UV-vis titrations, Se NMR, EPR, IR, MS, and electronic density calculations. and quantitatively detect Sec within a micromolar concentration range, achieving the limit of detection as low as 0.31 and 0.12 μM, respectively, within just 5 min. Remarkably, these chemodosimeters can also be conveniently employed to detect Sec in living cells.