Complexation of curium(III) by adenosine 5′-triphosphate (ATP): A time-resolved laser-induced fluorescence spectroscopy (TRLFS) study

Abstract

The complex formation of curium(III) with adenosine 5′-triphosphate (ATP) was determined by time-resolved laser-induced fluorescence spectroscopy (TRLFS). The interaction between soluble species of curium(III) with ATP was studied at trace Cm(III) concentrations (3 × 10 −7 M). The concentrations of ATP were varied between 6.0 × 10 −7 and 1.5 × 10 −4 M in the pH range of 1.5–7.0 using 0.154 M NaCl as background electrolyte. Three Cm–ATP species, M pH qL r, could be identified from the fluorescence emission spectra: (i) CmH 2ATP + with a peak maximum at 598.6 nm, (ii) CmHATP with a peak maximum at 600.3 nm, and (iii) CmATP − with a peak maximum at 601.0 nm. The formation constants of these complexes were calculated from TRLFS measurements to be log β 121 = 16.86 ± 0.09, log β 111 = 13.23 ± 0.10, and log β 101 = 8.19 ± 0.16. The hydrated Cm–ATP species showed fluorescence lifetimes between 88 and 96 μs; whereas the CmATP − complex has a significantly longer fluorescence lifetime of 187 ± 7 μs.