Spectroscopic study on the binding of Mn(II) to EHPG

Under the conditions of 0.05 mol x L(-1) Hepes buffer at room temperature and pH 7.4, the interaction of ethylene-N,N'-bis(o-hydroxyphenylglycine) (EHPG) and Mn(II) was investigated by both fluorescence and UV difference spectra. Results showed that the molar ratio of the complex is 1:1. With the addition of manganese ions, the fluorescence peak of EHPG at 310 nm decreased, while the peaks of UV absorptivity at 238 and 291 nm increased. The molar absorptivity of Mn(II) to EHPG at 238 nm is (1.31 +/- 0.02) x 10(4) cm(-1) x mol(-1) L. The disassociation constant for Mn-EHPG was determined to be (1.36 +/- 0.21) x 10(-5). It can be concluded that the binding of Mn(II) to EHPG is not a strongly binding reaction.