Nucleobase pair–metal dimer/dinuclear
metal cation interactions
play an important role in biological applications because of their
highly symmetrical structures and high stabilities. In this work,
we have selected five adenine–adenine hydrogen bonding, adenine–thymine
(AT), adenine–uracil, adenine–adenine stacking pairs,
and Watson–Crick AT stacking pairs and studied their interaction
with the coinage metal dimer M
2
and M
2
2+
metal cations, where M = Ag, Au, and Cu. Quantum chemical calculations
have been carried out with density functional theory (DFT) and time-dependent
DFT (TDDFT) methods. Electronic structures were analyzed by the partial
density of states method. During interactions, we find that M–M
distances are shorter than the sum of van der Waals radii of the corresponding
two homocoinage metal atoms, which show the existence of significant
metallophilic interactions. Results indicated that nucleobase–M
2
2+
complexes are stronger as compared to nucleobase–M
2
complexes. Also, the replacement of the hydrogen bond by
the dinuclear metal cation-coordinated bond forms more stable alternative
metallo-DNA sequences in AAST base pairs. TDDFT calculations reveal
that nucleobase–Cu
2
complexes and nucleobase–Ag
2
2+
/Au
2
2+
complexes can be
used for fluorescent markers and logic gate applications. Atom-in-molecules
analysis predicted the noncovalent interaction in these complexes.