Methoxy-Substituted TQEN Family of Fluorescent Zinc Sensors

Two methoxy-substituted TQEN (N,N,N‘,N‘-tetrakis(2-quinolylmethyl)ethylenediamine) derivatives, T(MQ)EN (N,N,N‘,N‘-tetrakis(6-methoxy-2-quinolylmethyl)ethylenediamine) and T(TMQ)EN (N,N,N‘,N‘-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)ethylenediamine), have been prepared, and their fluorescence properties with respect to Zn2+ coordination
were investigated. Introduction of a methoxy substituent at 6-position of the quinoline ring enhances the fluorescence
intensity by 10-fold, and the three methoxy substituents in the 5,6,7-positions afford significant enhancement of the
long-wavelength component of the fluorescence of zinc complex. The substituents did not alter the binding affinity
of these compounds toward zinc ion significantly. T(MQ)EN was proved to be effective in detection of zinc ion in
cells by fluorescent microscopy.