A long-lived luminescence and EPR bimodal lanthanide-based probe for free radicals

摘要

We developed a novel spin-labeled terbium complex Tb3+/cs124-DTPA-TEMPO (1) by covalentlynlabeling a nitroxide radical on the terbium complex for monitoring free radicals of various areas. Thisnlanthanide complex probe shows a high EPR signal which resulted from the nitroxide radical moiety,nand is weakly luminescent which resulted from the intramolecular quenching effect of the nitroxidenradical on sensitised terbium luminescence. The intensity of both the EPR and luminescence can benmodulated by eliminating the paramagnetism of the nitroxide radical through recognition of a carboncenterednradical analyte and thus gives a quantification of the analyte. We have preliminarily appliednthis probe in the luminescent detection of model carbon-centered radicals and hydroxyl radicals ($OH).nThis probe is water-soluble and contains lanthanide-luminescence properties, favorable for the timeresolvednluminescence technique. The investigation of the intramolecular quenching process hasnshowed that the labeled nitroxide radical quenches multiple excited states of the terbium complex,nresulting in highly efficient quenching of terbium luminescence. This probe is the first example ofnintramolecular modulation of lanthanide luminescence by a nitroxide radical.