Intramolecular and water mediated tautomerism of solvated glycine

The understanding of prototropic tautomerism in water and the characterization of solvent effects on protomeric equilibrium pose significant challenges. Using molecular dynamics simulations based on state-of-the-art deep learning potential and enhanced sampling methods, we provide a comprehensive description of all configurational transformations in glycine solvated in water and determine accurate free energy profiles of these processes. We observe that the tautomerism between the neutral and zwitterionic forms of solvated glycine can occur by both intramolecular proton transfer in glycine and intermolecular proton transfer in the contact ion pair (anionic glycine and hydronium ion) or the separated ion pair (cationic glycine and hydroxide ion)

A Bulk Phase Transformation Drives Ammonia Synthesis on Barium Hydride

It is believed by some that the key to a successful industrial heterogeneous catalyst is a complex dynamical behavior, in which the catalyst is more than just a provider of catalytic sites. With the help of machine learning-driven molecular dynamics simulations, we show that this is indeed the case for the thermally activated synthesis of ammonia catalysed by BaH2. This system has recently been experimentally investigated and shown to act as a highly efficient catalyst for ammonia synthesis, if and only if it is alternately exposed first to N2 and then to H2 in a chemical looping process. Our simulations reveal that when first exposed to N2, BaH2 undergoes a profound change and it is transformed into a superionic mixed compound, BaH(2-2x)(NH)x, characterized by a high mobility of both hydrides and imides. This transformation is not limited to the surface but involves the entire catalyst. When this compound is exposed to H2 in the second step of the looping process, the ammonia is readily formed and released, a process greatly facilitated by the high ionic mobility. Once all the nitrogen hydrides are hydrogenated, the system reverts to its initial state and it is ready for the next looping process

Intramolecular and Water Mediated Tautomerism of Solvated Glycine

Understanding tautomerism and characterizing solvent effects on the dynamic processes pose significant challenges. Using enhanced-sampling molecular dynamics based on state-of-the-art deep learning potentials, we investigated the tautomeric equilibria of glycine in water. We observed that the tautomerism between neutral and zwitterionic glycine can occur through both intramolecular and intermolecular proton transfers. The latter proceeds involving a contact anionic-glycine–hydronium ion pair or separate cationic-glycine–hydroxide ion pair. These pathways with comparable barriers contribute almost equally to the reaction flux

Intramolecular and Water Mediated Tautomerism of Solvated Glycine

Understanding tautomerism and characterizing solvent effects on the dynamic processes pose significant challenges. Using enhanced-sampling molecular dynamics based on state-of-the-art deep learning potentials, we investigated the tautomeric equilibria of glycine in water. We observed that the tautomerism between neutral and zwitterionic glycine can occur through both intramolecular and intermolecular proton transfers. The latter proceeds involving a contact anionic-glycine–hydronium ion pair or separate cationic-glycine–hydroxide ion pair. These pathways with comparable barriers contribute almost equally to the reaction flux