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Moderating the acidity of Pb(II)-Water complexes through the coordination of non-aqueous ligands

journal contribution
posted on 2023-06-08, 09:29 authored by Hazel CoxHazel Cox, Georgina Aitken, Anthony J Stace
The metal dication Pb(II) is known to promote catalytic cleavage of the sugar-phosphate backbone in tRNA. The mechanism proposed to achieve this step requires that the [Pb(II)OH(-)](+) moiety act as a nucleophile and alter the local acidity of surrounding water molecules. MP2 calculations investigating the effect that nonaqueous bases have on the stability of dihydrated-Pb(II) show that the height and position of the proton-transfer barrier are sensitive to the presence of a single N- or O-coordinating "spectator" ligand and that, with the addition of two ligands coordinated directly to the Pb(II) center, the equilibrium for the hydrolysis reaction can shift to the left, thus making the Pb(II)-hydrate complex more stable than the Pb(II)-hydroxide complex. The calculations reveal a good correlation between the gas-phase basicities of nonaqueous ligands coordinated to the metal center and the barriers to proton transfer in [Pb(H(2)O)(2)](2+). In terms of the Pb(II)-induced hydrolysis of tRNA, these results indicate that the coordination of [Pb(II)-OH(-)](+) to uracil and cytosine in tRNA increases the basicity of the hydroxyl group and promotes nucleophilic attack of H(+).

History

Publication status

  • Published

Journal

Journal of Physical Chemistry A

ISSN

1089-5639

Publisher

American Chemical Society

Issue

11

Volume

116

Page range

3035-3041

Department affiliated with

  • Chemistry Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-05-30

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