Fluorescence Quenching of the Europium Tetracycline Hydrogen Peroxide Complex by Copper (II) and other Metal Ions

Abstract

The europium-tetracycline complex [Eu(Tc)] is known to show only weak fluorescence with an emission maximum at 615 nm. On addition of hydrogen peroxide (HP), the strongly fluorescent [Eu(Tc)(HP)] complex is formed, which displays a 15-fold stronger luminescence intensity. This study describes the decrease in luminescence intensity of the [Eu(Tc)(HP)] complex in aqueous solution in the presence of Cu2+, Fe3+, Ag+, Al3+, Zn2+, Co2+, Ni2+, Mn2+, Ca2+, and Mg2+. Static and dynamic quenching can be induced by Cu2+, and these processes were quantified by means of their quenching constants. Stern-Volmer plots were also derived from lifetime imaging measurements accomplished by the rapid lifetime determination (RLD) technique based on microwell plate assays, and also by the time-correlated single photon counting (TCSPC) technique. According to those data, a time-resolved fluorescent method for copper determination can be proposed that is based on dynamic quenching of the [Eu(Tc)(HP)] complex by Cu2+ ions. The response to copper concentrations is linear up to 1.6 micromol L(-1), providing a detection limit of 0.2 micromol L(-1).

UV Emission of Gd3+ in the Presence of Cu2+: Towards Luminescence Quenching through Quantum Cutting?

“…[10][11][12][13] In fact, the underlying energy transfer has been investigated for the development of analytical methods to detect trace amounts of copper(II). [10][11][12][13] Nevertheless, the influence of Cu 2 + on Gd 3 + emission properties remains unexplored to the best of the author's knowledge. Divalent copper ions dispersed in phosphate glass have been reported to contribute to host absorption deep in the UV region (e.g.…”

“…[11,13] The inset of Figure 3 shows such a plot constructed with the PL peak intensities of the 6 P 7/2 ! 8 S 7/2 transition versus CuO concentration in the Gd and GdCu0.2-0.6 glasses.…”

Luminescent Chemical and Physical Sensors Based on Lanthanide Complexes

“…It can be used to detect hydrogen peroxide in river water [39] or to monitor the activity of enzymes that convert or produce hydrogen peroxide such as glucose oxidase, catalases, or peroxidases [40][41][42]. Due to its quenching effect, the determination of copper ions also can be achieved by the EuTc hydrogen peroxide complex [43].…”

Fluorescent probe for copper(II) ion based on a rhodamine spirolactame derivative, and its application to fluorescent imaging in living cells

“…Because of its operational simplicity, low cost, real time monitoring and high selectivity, fluorescent detection has become the promising strategy used for Cu 2+ detection. Even though considerable efforts have been undertaken to develop fluorescent probes for Cu 2+ , many reported fluorescent probes generally undergo fluorescence quenching upon binding with its inherent paramagnetic nature [4][5][6][7][8][9][10], which is not as sensitive as a fluorescence enhancement response. Recently there are still a few examples reported wherein enhancement in the fluorescence intensity has been observed upon complexation with Cu 2+ ions [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”