Synthesis and photophysical properties of a fluorescent TREN-type ligand incorporating the coumarin chromophore and its zinc complex

A new, UV-excited fluorescent Zn2+ indicator was synthesized and the spectral profile of its free and Zn2+ bound forms were studied. The fluorescent properties of this probe are due to the 7-amino-4-methylcoumarin fluorophore, which is conjugated with the tris(2-aminoethyl)amine (TREN) that functions as the zinc-chelating moiety. The compound exhibits a Zn2+ dissociation constant of 18.0 μM. The fluorescence spectra of the probe showed a clear shift in excitation wavelength maxima upon Zn2+ binding, indicating its potential use as ratiometric Zn2+ indicator.