One-bond ¹³C–¹³C spin-coupling constants in saccharides: a comparison of experimental and calculated values by density functional theory using solid-state ¹³C NMR and X-ray crystallography

Journal Article · Thu May 11 00:00:00 EDT 2023 · Physical Chemistry Chemical Physics. PCCP

DOI:https://doi.org/10.1039/d2cp05363b· OSTI ID:2418867

Tetrault, Timothy ^[1]; Meredith, Reagan J. ^[2]; Yoon, Mi-Kyung ^[3]; Canizares, Christopher ^[2]; Oliver, Allen G. ^[4]; Carmichael, Ian ^[5]; Serianni, Anthony S. ^[2]

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1. University of Notre Dame, IN (United States); OSTI
2. University of Notre Dame, IN (United States)
3. University of Notre Dame, IN (United States); Omicron Biochemicals, Inc., South Bend, IN (United States)
4. University of Notre Dame, IN (United States). Molecular Structure Facility
5. University of Notre Dame, IN (United States). Radiation Laboratory

Methyl aldohexopyranosides were ¹³C-labeled at contiguous carbons, crystallized, and studied by single-crystal X-ray crystallography and solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy to examine the degree to which density functional theory (DFT) can calculate one-bond 13C–13C spin-coupling constants (¹J_CC) in saccharides with sufficient accuracy to permit their use in MA'AT analysis, a newly-reported hybrid DFT/NMR method that provides probability distributions of molecular torsion angles in solution (Zhang et al., J. Phys. Chem. B, 2017, 121, 3042–3058; Meredith et al., J. Chem. Inf. Model., 2022, 62, 3135–3141). Experimental ¹J_CC values in crystalline samples of the doubly ¹³C-labeled compounds were measured by solid-state ¹³C NMR and compared to those calculated from five different DFT models: (1) ¹J_CC values calculated from single structures identical to those observed in crystalline samples by X-ray crystallography (all atom refinement); (2) ¹J_CC values calculated from the single structures in (1) but after Hirshfeld atom refinement (HAR); (3) ¹J_CC values calculated from the single structures in (1) after DFT-optimization of hydrogen atoms only; and (4 and 5) ¹J_CC values calculated in rotamers of torsion angle θ₂ (C1–C2–O2–O2H) or ω(C4–C5–C6–O6) from which either specific or generalized parameterized equations were obtained and used to calculate ¹J_CC values in the specific θ₂ or ω rotamers observed in crystalline samples. Good qualitative agreement was observed between calculated ¹J_CC values and those measured by solid-state ¹³C NMR regardless of the DFT model, but in no cases were calculated ¹J_CC values quantitative, differing (over-estimated) on average by 4–5% from experimental values. These findings, and those reported recently from solution NMR studies (Tetrault et al., J. Phys. Chem. B 2022, 126, 9506–9515), indicate that improvements in DFT calculations are needed before calculated ¹J_CC values can be used directly as reliable constraints in MA'AT analyses of saccharides in solution.

• Research Organization: University of Notre Dame, IN (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FC02-04ER15533
• OSTI ID: 2418867
• Journal Information: Physical Chemistry Chemical Physics. PCCP, Journal Name: Physical Chemistry Chemical Physics. PCCP Journal Issue: 23 Vol. 25; ISSN 1463-9076; ISSN PPCPFQ
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

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