Synthesis of a Polyaminopolycarboxylic Acid and Fluorescence of Tb^(3+) Complexes in Aqueous Solution

A new polyaminopolycarboxylic acid, diethylenetriamine N′,N bi( p acetoamino salicylic acid) N′,N″,N triacetic acid(DTPA·2pAS), has been synthesized DTPA·2pAs can sensitize the luminescence of Tb 3+ and Dy 3+ in aqueous solution Fluorescent titration at pH 7 0 indicated a 1∶1 composition of Tb 3+ to DTPA·2pAS for the complexes The complexes exhibit intensely sensitized fluorescence in a range of pH 5 0～12 0 The fluorescence intensity of the complexes increased as the concentration was raised from 1×10 -7 to 1×10 -4 mol/L, and then decreased at 1×10 -3 mol/L due to concentration quenching A replacement of EDTA with DTPA·2pAs in Tb 3+ EDTA complex solution led to increasement in Tb 3+ sensitized luminescence intensity, suggesting formation of Tb 3+ DTPA·2pAS complexes and higher stability of these complexes than those of Tb 3+ EDTA, which has been confirmed by determination of stability constants with pH potentiometric titration The results show that DTPA·2pAS may be applied to fluorescent immunoassay as a “fluorescence enhancement solution”

Stability Constants and Fluorescence of Terbium(Ⅲ) Complexes with Polyaminopolycarboxylates in Aqueous Solution

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