Abstract Guanosine (G) historically facilitates G‐quartet assembly, a non‐canonical DNA secondary structure primarily stabilized by K + ions. Herein, it is reported that mercurous ion (dimercury(I), Hg–Hg 2+ , G:Hg + = 1:0.5–1.5) forms a significantly more stable G‐quadruplex G 8 ·Hg 2 2+ than the well‐known G 4 ·K + . G 8 ·Hg 2 2+ self‐assembles in water through J‐type stacking via an isodesmic mechanism, creating stable supramolecular polymers (SPs) crosslinked to produce thermo‐reversible self‐healing hydrogels. Dimercury(I) more efficiently promotes the formation of G‐quadruplex SP with enhanced stability, which is evident from its higher tolerance to aging, dilution, and temperature. This enhanced stability is attributed to the covalent Hg + ─Hg + bond, which holds two G‐tetrads together, thereby greatly stabilizing the octameric G‐quadruplex G 4 ·Hg + −Hg + ·G 4 and exhibiting a significantly higher binding energy than G 4 ·K + ·G 4 , as determined computationally. Despite this enhanced stability, G 8 ·Hg 2 2+ SP gel exhibits excellent anion responsiveness, either breaking or solubilizing the G‐quadruplex SP, unlike G 4 ·K + gel. Moreover, at higher metal ratios (Hg + > 1.5), a thermodynamically stable G 2 ·(Hg 2 2+ ) 2 dimeric assembly is formed, whereas mercuric ion (Hg 2+ ) supported dimeric complexation G 2 ·Hg 2+ 2 regardless of the metal ratio. These results suggest that Hg ions, irrespective of their oxidation state (I/II), have a strong affinity for binding with G, potentially providing insights into the molecular basis of Hg's genotoxicity.
Mohanta et al. (Thu,) studied this question.