Two-dimensional condensation of guanidinium nitrate at the mercury-water interface

Condensation of Nucleobases at Mercury/Aqueous Solution Interface–A Structural Perspective Using Hydrogen Bonding Considerations

“…The stabilization energy of guanidinium nitrate due to H bonds becomes 6E B + 6E C viz 552.3 kJmol −1 . Substituting this value in the regression equation derived in the text, we obtain T * as approximately 357.35 ± 8.30 K in satisfactory agreement with the experimental critical temperature (54, 55) of 362 K. In contrast to the crystallographic structure of guanidinium nitrate (54,55), which is devoid of solvent molecules, the above structure takes into account the presence of solvated ions of the supporting electrolyte, which leads to the stabilization of the quadruplex forms by occupying the hollow space created by H bonds and hence is applicable in the electrochemical context.…”

“…• lower than that of guanidinium nitrate (54,55), since the nonelectrostatic interaction of guanidinium nitrate is higher. ( H cond of guanidinium nitrate calculated in Appendix C is approximately 184.1 kJ mol −1 higher than that of guanine.)…”

“…Analogous considerations may hold good for other nucleobases and related adsorbates. In the case of thymine and guanidinium nitrate (Appendix C) condensing at Hg electrodes (54,55), the crystallographic structure obtained by evaporating the solvent ("salting out") indicate respectively multilayers of thymine and pseudotrigonal structure of guanidinium nitrate, which are valid essentially in the absence of solvated electrolyte ions. The anions of the supporting electrolyte such as F-stabilize and enhance the formation of uracil films, and the effect of other anions have also been discussed (46).…”

Lattice Gas Model for the Adsorption of Guanidinium Nitrate at the Mercury−Water Interface

“…The interfacial properties of salts which form condensed monolayers at the mercury−water interface have been the focus of some recent experiments. − The interfacial properties of one such salt, guanidinium nitrate 4,9 (see Figure ), led de Levie et al. to conjecture a plausible structure for the condensed monolayer which forms at the interface 1 Illustration of the hydrogen bonding (dotted lines) between a nitrate anion, NO 3 - , and a guanidinium cation, C(NH 2 ) 3 + .…”

“…The X-ray crystal structure of the salt showed the presence of planes of hydrogen-bonded structures. This led to the conjecture 9 that a condensed monolayer is present at the mercury−water interface which consists of a planar hexagonal array of hydrogen-bonded guanidinium and nitrate ions, each ion having a trigonal planar structure which supports six hydrogen bonds to neighboring ions (see Figure 8 of ref ). A comparison of the inhibition of electron transfer through this condensed monolayer with that through a condensed monolayer of monomethylguanidinium nitrate supports the conjecture of an open hydrogen-bonded structure …”