Dimalonate[C-60]fullerene protonation and complexation with uranyl in aqueous solution. Spectrophotometric study

摘要

Protonation of water-soluble e-dimalonate[C-60]fullerene (L4-) was investigated using UV spectrophotometry and data analyzed using a general least-squares minimization approach. The protonation constants determined were (L4- + rH(+) double left right arrow LHrr-4, log * beta(01r); log * beta(011) = 6.19+/-0.02; log * beta(012) = 10.57+/-0.01; log * beta(013) = 13.68+/-0.02; log * beta(014) = 15.85+/-0.02; 25 degreesC). Complex equilibria study proved the formation of UO2LH- and (UO2)(2)L complexes (pUO(2)(2+) + qL(4-) + rH(+) double left right arrow (UO2)(p)LqHr2p-4q + (r), log * beta(pqr); log * beta(111) = 11.0+/-0.2; log * beta(210) = 14.35+/-0.09; 25 degreesC). The stability constant for the binding of the first uranyl ion with the dimalonate fullerene ligand is log beta(11)(ML) 4.81 and the second one log K-21 (ML + M = M2L) = 3.35, thus, uranyl complexation with the second malonate is much lower. The first value (4.81) is near to log K-1 = 4.88 for uranyl-malonate 1: 1 complex. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 36]