Terbium Oxalatophosphonate as Efficient Multiresponsive Luminescent Sensors for Chromate Anions and Tryptophan Molecules

A stable 2D terbium oxalatophosphonate
with green luminescence,
namely, [Tb2(H3L)­(C2O4)3(H2O)4]·2H2O (1), has been hydrothermally obtained by using (4-carboxypiperidyl)-N-methylenephosphonic acid (H3L) and oxalate
ligand. The luminescent investigation indicates that the emission
behavior of compound 1 shows high water and pH stabilities.
It can be applied as a multiresponsive luminescent probe with high
selectivity, high sensitivity, recycling capability, and fast sensing
of CrO42–, Cr2O72– anions and tryptophan (Trp)
molecules in aqueous solution through the luminescence quenching effect.
Moreover, the sensing results can be distinguished by the naked eye
under the irradiation of UV light of 254 nm. In addition, the probable
mechanisms for the quenching behavior are also discussed, which can
be mainly attributed to the competitive absorption of excitation energy
between compound 1 and the analytes.