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. Author manuscript; available in PMC: 2011 Sep 15.
Published in final edited form as: Inorg Chem. 2010 May 3;49(9):4156–4166. doi: 10.1021/ic902219t

Figure 4.

Figure 4

(a) Luminescence spectra (left) for solutions of [Yb(H(2,2)-Me-3,2-HOPO)]– (ca. 1.5 μM in 0.1 M TRIS at pH 7.4; black line) and after addition of up to ca. 500 equivalents of DTPA (red). (b) Double log plot (right) of equilibrium metal complex concentrations log[[Yb(DTPA)]/[Yb(H(2,2)-Me-3,2-HOPO)]] determined from luminescence spectra versus equilibrium concentrations of log[[DTPA]/[H(2,2)-Me-3,2-HOPO]] and corresponding fit used to evaluate equal speciation between H(2,2)-Me-3,2-HOPO and DTPA (i.e. 50 % [Yb(DTPA)] at ca. 0.013 mM, which corresponds to a pYb = 21.9 (1) for the [Yb(H(2,2)-Me-3,2-HOPO)] complex.