ArticlePhysical chemistry chemical physics : PCCP2015
Demystifying fluorine chemical shifts: electronic structure calculations address origins of seemingly anomalous (19)F-NMR spectra of fluorohistidine isomers and analogues.
Article in Physical chemistry chemical physics : PCCP, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers.
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Who cites it
11 citing papers in PubMed.
- Electronic Modification of a Reduced Mononuclear Nonheme Iron Nitrosyl Complex Leads to HNO Release.Journal of the American Chemical Society · 2025Article
- A Quest for EffectiveInternational journal of molecular sciences · 2025Article
- AdvancingThe journal of physical chemistry. A · 2024Article
- Synthesis and application of aRSC chemical biology · 2021Article
- PredictingAngewandte Chemie (International ed. in English) · 2020Article
- Exploring IDP-Ligand Interactions: tau K18 as A Test Case.International journal of molecular sciences · 2020Article
- Prediction ofThe Journal of organic chemistry · 2018Article
- Evaluating electronic structure methods for accurate calculation ofJournal of computational chemistry · 2017Article
- Genetic incorporation of 4-fluorohistidine into peptides enables selective affinity purification.Organic & biomolecular chemistry · 2017Article
- The Biophysical Probes 2-fluorohistidine and 4-fluorohistidine: Spectroscopic Signatures and Molecular Properties.Scientific reports · 2017Article
- Tautomeric stabilities of 4-fluorohistidine shed new light on mechanistic experiments with labeled ribonuclease A.Chemical physics letters · 2016Article
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3 authors.
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Abstract
Fluorine NMR spectroscopy is a powerful tool for studying biomolecular structure, dynamics, and ligand binding, yet the origins of (19)F chemical shifts are not well understood. Herein, we use electronic structure calculations to describe the changes in (19)F chemical shifts of 2F- and 4F-histidine/(5-methyl)-imidazole upon acid titration. While the protonation of the 2F species results in a deshielded chemical shift, protonation of the 4F isomer results in an opposite, shielded chemical shift. The deshielding of 2F-histidine/(5-methyl)-imidazole upon protonation can be rationalized by concomitant decreases in charge density on fluorine and a reduced dipole moment. These correlations do not hold for 4F-histidine/(5-methyl)-imidazole, however. Molecular orbital calculations reveal that for the 4F species, there are no lone pair electrons on the fluorine until protonation. Analysis of a series of 4F-imidazole analogues, all with delocalized fluorine electron density, indicates that the deshielding of (19)F chemical shifts through substituent effects correlates with increased C-F bond polarity. In summary, the delocalization of fluorine electrons in the neutral 4F species, with gain of a lone pair upon protonation may help explain the difficulty in developing a predictive framework for fluorine chemical shifts. Ideas debated by chemists over 40 years ago, regarding fluorine's complex electronic effects, are shown to have relevance for understanding and predicting fluorine NMR spectra.
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