Condensation Product of 4-Methoxybenzaldehyde and Ethylenediamine: "Off-On" Fluorescent Sensor for Cerium(III).

The condensation product (L) of 4-methoxybenzaldehyde and ethylenediamine has been synthesised and characterised. L showed a 21 times enhancement in fluorescence intensity on interaction with Ce3+ in CH3OH at λmax = 360 nm when excited with 270 nm photons. Metal ions K+, Na+, Al3+, Co2+, Hg2+, Cd2+, Ni2+, Zn2+, Mn2+, Mg2+ and Ca2+ do not interfere. The stoichiometry of binding and the binding constants were determined from spectroscopic data and found to be 1:1 and 104.8 M respectively. The detection limit was found to be 10-5.2 M. The protonation/de-protonation of water molecules coordinated to Ce3+ was found to show interesting behaviour on the fluorescence of L:Ce3+.