Disassembly of intermolecular hydrogen bond induced by cations on self-assembled monolayer

Intermolecular hydrogen bond, a kind of basic van der Waals bonds, commonly exists in biological systems. As a fundamental step in biological metabolism, the disassembly process of hydrogen bond is necessary to be given more attention. Here, we have demonstrated the disassembly of intermolecular hydrogen bond by scanning electrochemical microscopy. The intermolecular hydrogen bond was designed between the hydroxyl of ferrocenemethanol (FcCH₂OH) and the carboxyl group of 3-mercaptopropionic acid (3-MPA), and FcCH₂OH was bonded on 3-MPA self-assembled monolayer modified electrode surface. Cation (Mg²⁺, Ca²⁺ or Ba²⁺), as an external stimulus, induced the disassembly of hydrogen bond by forming ion-pair with terminal carboxylate anion. Furthermore, the inducing capability of cation was Mg²⁺ < Ca²⁺ < Ba²⁺ in order based on the strength of ion-pairs between cation and carboxylate anion. The degree of disassembly was effectively regulated by the different ratio of additional mixed cations. According to the positive induction of cation on disassembly of intermolecular hydrogen bond, a practicable and effective approach was provided for field application of molecular recombination and medical bioengineering.