Figure 5.

Most stable adducts of guanine interacting with Na⁺-montmorillonite through the Na⁺-free side in non-hydrated conditions in a perpendicular (A) and parallel (B) way, through the Na⁺-containing side in non-hydrated conditions adopting cation–π/ring (C), cation–π/displaced (D), and cation–heteroatom interactions (adapted from [124]). Representative structures for cytosine interacting with Na⁺-montmorillonite in hydrated conditions ((F,G), adapted from [125]). The most stable adduct of guanine interacting with an acidic external surface of montmorillonite ((H), adapted from [126]).