Acid Base Chemistry of Short Hydrogen Bonds: A Tale of Schrödinger's Cat in Glutamine-Derived Crystals

Fuente: arXiv
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Auteurs principaux: Qaisrani, Muhammad Nawaz, Kumar, Nandha, Dreßler, Christian, Gebauer, Ralph, Hassanali, Ali
Format: Preprint
Publié: 2025
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author Qaisrani, Muhammad Nawaz
Kumar, Nandha
Dreßler, Christian
Gebauer, Ralph
Hassanali, Ali
author_facet Qaisrani, Muhammad Nawaz
Kumar, Nandha
Dreßler, Christian
Gebauer, Ralph
Hassanali, Ali
contents Short hydrogen bonds (SHBs), defined by donor-acceptor distances below 2.5 Angstrom, represent a distinct regime in acid-base chemistry where conventional models of hydrogen bonding break down. In an organic crystal formed via a temperature-induced chemical transformation of L-glutamine, we previously identified an SHB that is permissive to proton transfer, leading to a characteristic double-well potential implying an activated process. Herein, using path-integral ab initio molecular dynamics (PI-AIMD), we show that nuclear quantum effects (NQEs) completely eliminate the classical barrier, leading to a symmetrization of the proton along the hydrogen bond. While in the classical case the proton transfer is strongly coupled to the rocking modes of the ammonium ion in the crystal, NQEs significantly reduce these correlations. Examining the electronic structure through Wannier centers (WCs) further reveals a quantum-driven redistribution of bonding electrons, blurring the distinction between hydrogen bonding and covalency. Taken together, our findings indicate that NQEs in this organic crystal lead to a situation where both the donor and acceptor can simultaneously act as both an acid and a base.
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id arxiv_https___arxiv_org_abs_2505_08893
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Acid Base Chemistry of Short Hydrogen Bonds: A Tale of Schrödinger's Cat in Glutamine-Derived Crystals
Qaisrani, Muhammad Nawaz
Kumar, Nandha
Dreßler, Christian
Gebauer, Ralph
Hassanali, Ali
Chemical Physics
Short hydrogen bonds (SHBs), defined by donor-acceptor distances below 2.5 Angstrom, represent a distinct regime in acid-base chemistry where conventional models of hydrogen bonding break down. In an organic crystal formed via a temperature-induced chemical transformation of L-glutamine, we previously identified an SHB that is permissive to proton transfer, leading to a characteristic double-well potential implying an activated process. Herein, using path-integral ab initio molecular dynamics (PI-AIMD), we show that nuclear quantum effects (NQEs) completely eliminate the classical barrier, leading to a symmetrization of the proton along the hydrogen bond. While in the classical case the proton transfer is strongly coupled to the rocking modes of the ammonium ion in the crystal, NQEs significantly reduce these correlations. Examining the electronic structure through Wannier centers (WCs) further reveals a quantum-driven redistribution of bonding electrons, blurring the distinction between hydrogen bonding and covalency. Taken together, our findings indicate that NQEs in this organic crystal lead to a situation where both the donor and acceptor can simultaneously act as both an acid and a base.
title Acid Base Chemistry of Short Hydrogen Bonds: A Tale of Schrödinger's Cat in Glutamine-Derived Crystals
topic Chemical Physics
url https://arxiv.org/abs/2505.08893