FIG. 12.

The anionic phosphate groups non-covalently interact with each other, the deoxyribose sugars, and the aromatic nucleobases. The combined effect of these nonlocal forces is an “intermolecular” stress arising near the phosphate group. When a guanidinium cation neutralizes one of the phosphate groups, it also modifies these non-covalent interactions and the resulting intermolecular stress. Modification of denticity and positioning further adjust the character of the non-covalent interactions, allowing for a diverse array of tunable “knobs” that induce particular kinds of mechanical deformation.