Abstract
A fluorescent aminoacid was designed for selective and sensitive detection of Cu(II) in aqueous solution. The designing of this Cu(II) fluorescent chemosensing molecule, N Β± (1βnaphthyl). aminoacetic acid (NAA), was based on the binding of Cu(II) to aminoacetic acid and the novel charge transfer photophysics of 1βaminonaphthalenes. The fluorescence of NAA was found quenched by Cu (II) and several other metal ions of similar electronic structure such as Co(II), Ni(II) and Zn(II). The quenching was shown to occur via electron transfer within the metalβNAA complex, which required an optimal combination of high binding affinity and favorable redox properties of the components in the metalβNAA complex and hence afforded selective fluorometric detection of Cu(II). The calibration graph obeyed SternβVolmer theory and was shown for Cu(II) over the range of 0β2.75 Β± 10β^4^ mol/L. The quenching constant of Cu(II) was measured as 8.0 Β± 10^3^ mol/L that was two orders of magnitude higher than those of Co(II), Ni(II) and Zn(II). The 3SD limit of detection for Cu(II) was 8.00 Β± 10^β6^ mol/L with a coefficient of variation of 1.65%. Linear range for quantitative detection of Cu(II) was 2.67 Β± 10^β5^β2.75 Β± 10^β4^ mol/L. The method was applied to synthetic sample measurements which gave recoveries of 105%β112%.