Identification of beryllium fluoride complexes in mechanically distorted gels using quadrupolar split <SUP>9</SUP>Be NMR spectra resolved with solution-state selective cross-polarization
File(s)
Accepted version
Author(s)
Romanenko, Konstantin
Elliott, Stuart J
Shubin, Aleksandr A
Kuchel, Philip W
Type
Journal Article
Abstract
The uniformly anisotropic media afforded by hydrogels are being increasingly exploited in analytical (structure elucidation) nuclear magnetic resonance (NMR) spectroscopy, and in studies of mechanosensitive biophysical and biochemical properties of living cells. The 9Be NMR parameters of beryllium fluoride complexes formed in aqueous solutions are sensitive markers of the anisotropic molecular environments produced by gelatin gels. The electric quadrupole moment of the 9Be nucleus (spin I = 3/2) interacts with the electric field gradient tensor in a stretched (or compressed) gel, giving rise to the splitting of peaks in 9Be NMR spectra. These are in addition to those produced by scalar coupling to the 19F nuclei. Thus, an equilibrium mixture of beryllofluoride complexes (BeF2, BeF3−, and BeF42−) in mechanically distorted gels generates an envelope of overlapping 9Be NMR multiplets. In the present work, the multiplets were dissected apart by using selective excitation of 9Be–19F cross-polarization; and the spectral components were quantified with multi-parameter line-shape decomposition, coupled with SpinDynamica simulations. The effects of gel density and Bloom number (a measure of gelatin-gel rigidity under standard conditions of sample preparation) on residual quadrupolar splittings were examined. Cross-polarization experiments revealed a bimodal distribution of residual quadrupolar coupling constants (RQC) of the BeF3− complexes. The average RQC of the dominant BeF3− population was ∼3 times larger than that of BeF42−. The secondary BeF3− population existed in a tetrahedral configuration. It was attributed to BeF3− complexes associated with negatively charged –COO− groups of the denatured collagen matrix.
Date Issued
2021-08-21
Date Acceptance
2021-07-16
Citation
Physical Chemistry Chemical Physics, 2021, 23 (31), pp.16932-16941
ISSN
1463-9076
Publisher
Royal Society of Chemistry
Start Page
16932
End Page
16941
Journal / Book Title
Physical Chemistry Chemical Physics
Volume
23
Issue
31
Copyright Statement
© the Owner Societies 2021. Published by the Royal Society of Chemistry.
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/34337629
Subjects
ALIGNMENT
ALUMINUM
ANALOGS
AQUEOUS-SOLUTION
BERYLLOFLUORIDE COMPLEXES
BICELLES
Chemistry
Chemistry, Physical
COORDINATION CHEMISTRY
GAMMA-PHOSPHATE
NUCLEAR-MAGNETIC-RESONANCE
Physical Sciences
Physics
Physics, Atomic, Molecular & Chemical
Science & Technology
SPECTROSCOPY
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2021-07-17