DOI
10.1021/acs.jpca.1c07554
Abstract
Halogen bonding (XB) is a highly directional, non-covalent intermolecular interaction between a molecule (XB donor) presenting a halogen with an electron-deficient region or sigma hole (σ-hole) and an electron-rich or Lewis-base molecule (XB acceptor). A systematic, experimental, and theoretical study of solution-phase XB strength as a function of the molecular structure for both XB donor and acceptor molecules is presented. The impact of specific structural features is assessed using 19F and 1H nuclear magnetic resonance (NMR) titrations to determine association constants, density functional theory calculations for interaction energies and bond lengths, as well as 19F–1H HOESY NMR measurements of intermolecular cross-relaxation between the interacting XB donor–acceptor adducts. For XB donor molecules (perfluoro-halogenated benzenes), results indicate the critical importance of iodine coupled with electron-withdrawing entities. Prominent structural components of XB acceptor molecules include a central atom working in conjunction with a Lewis-base atom to present high electron density directed at the σ-hole (e.g., tributylphosphine oxide). Additionally, larger surrounding aliphatic R groups (e.g., butyl and octyl) were found to significantly stabilize strong XB, particularly in solvents that promote the interaction. With a more thorough understanding of structure-optimized XB, one can envision harnessing XB interactions more strategically for specific design of optimal materials and chemical applications.
Document Type
Article
Publication Date
10-18-2021
Publisher Statement
Copyright © 2021, American Chemical Society.
DOI: https://doi.org/10.1021/acs.jpca.1c07554
The definitive version is available at: https://arc.net/l/quote/lidwczcw
Recommended Citation
Quang Minh Dang, Jeffrey H. Simpson, Carol A. Parish, and Michael C. Leopold. "Evaluating Halogen-Bond Strength as a Function of Molecular Structure Using Nuclear Magnetic Resonance Spectroscopy and Computational Analysis.",
The Journal of Physical Chemistry A, 2021 125 (42), 9377-9393. DOI: 10.1021/acs.jpca.1c07554