A β-diketonate−europium(III) complex-based time-gated luminescence probe for selective visualization of peroxynitrite in living cells

Abstract

Herein, we designed and synthesized a new β-diketonate−Eu3+ complex-based luminescent probe for peroxynitrite (ONOO−), Eu(hdph)3(tpy), by using a 2,4-dimethoxyphenyl-substituted β-diketone ligand 1,1,1,2,2,3,3-hetafluoro-6-(2,4-dimethoxyphenyl)-4,6-hexanedione (hdph) and a coligand 2,2′,2″-terpyridine (tpy). The probe exhibits strong fluorescence with a great quantum yield of 25.6%. Upon the addition of ONOO−, the luminescence of Eu(hdph)3(tpy) at 607 nm was dramatically quenched due to the interaction of the 2,4-dimethoxyphenyl moiety with ONOO−, which leads to the deactivation of the excited Eu3+ complex and a 71-fold luminescence decrease. The dose-dependent luminescence decrease showed good linear relationship against the ONOO− concentration with the detection limit at nano-molar concentration level. In addition, the luminescence response of Eu(hdph)3(tpy) to ONOO− displayed high specificity over various reactive oxygen/nitrogen species. Taking advantage of the high sensitivity and specificity, Eu(hdph)3(tpy) was applied for the time-gated luminescence imaging of ONOO− in HepG2 cells. The results demonstrated the practical applicability of Eu(hdph)3(tpy) as a luminescent probe for the long-term visualization of intracellular ONOO−.