Dinuclear Metal-Mediated Guanine–Uracil Base Pairs: Theoretical Studies of GUM22+ (M = Cu, Ag, and Au) Ions

Abstract

Dinuclear metal-mediated hetero base pairs with the d10–d10 closed-shell interactions have significant stability. It is interesting to identify whether coinage metal-mediated Wobble base pairs are also stable. Geometric and electronic structures of the lowest-lying isomers of GUM22+ (G = guanine, U = uracil, M = Cu, Ag, and Au) cluster ions were investigated with density functional theory. In the lowest-lying isomers of these dinuclear metal-mediated base pairs, the 2-oxo-4-hydroxy-trans-N1H isomer of uracil is derived from the canonical tautomer of uracil by the hydrogen atom transfer. M22+ cations remain as an unbroken unit and interact with the G···U ligand through two sets of closely linear N···M···O units, while the reciprocal hydrogen bonds between the Wobble base pair (G–U) are entirely substituted by the M–N or M–O interactions in these complexes. The atoms in molecules and EDA–NOCV calculations really reveal that the σ interactions in GUM22+ cations are the paramount term of ΔEOrb. The obtained instantaneous interaction energies ΔEint and bond dissociation energies of the metal–ligand interactions give the trend of the bond strength as Cu > Au > Ag.