Table 2.
Calculated and room temperature experimental 13C chemical shifts for standard compounds.
| Site | Method | Calcd CS [ppm] | Exp. CS [ppm] | Deviation [ppm] |
|---|---|---|---|---|
| α‐Gly,[d] CO | DFT‐D | 179.3 | 176.562 | +2.8 |
| α‐Gly, CH2 | DFT‐D | 41.8 | 43.762 | −1.9 |
| γ‐Gly, CO | DFT‐D | 176.4 | 173.462 | +3.0 |
| γ‐Gly, CH2 | DFT‐D | 40.1 | 41.462 | −1.3 |
| ADA,[e] CH | MD | 30.9 | 29.563 | +1.4 |
| ADA, CH2 | MD | 39.4 | 38.563 | +0.9 |
| HMB,[f] CH (aromatic) | MD | 129.4 | 132.063 | −2.6 |
| HMB, CH3 (aliphatic) | MD | 16.1 | 17.263 | −1.1 |
| 3‐MGA,[g] COOH (1) | MD | 179.0 | 180.7[h] | −1.7 |
| 3‐MGA, COOH (2) | MD | 179.7 | 181.6[h] | −1.9 |
| 3‐MGA, CH2 (1) | MD | 40.0 | 38.3[h] | +1.7 |
| 3‐MGA, CH2 (2) | MD | 42.9 | 39.5[h] | +3.4 |
| 3‐MGA, CH | MD | 24.1 | 25.2[h] | −1.1 |
| 3‐MGA, CH3 | MD | 17.3 | 18.8[h] | −1.5 |
| Reference shielding [ppm] | 168.9 | |||
| MAD [ppm] | 1.9 | |||
| RMSD [ppm] | 2.0 | |||
[a] Calcd CS: calculated chemical shift. [b] Exp. CS: experimental chemical shift. [c] Deviation=Calcd CS−Exp. CS. [d] Gly: glycine. [e] ADA: adamantane. [f] HMB: hexamethylbenzene. [g] 3‐MGA: 3‐methylglutaric acid. [h] Unpublished data, provided by Dr. Sean Delaney and Prof. Dr. Eric Munson. [i] MAD: mean absolute deviation. [j] RMSD: root‐mean‐square deviation.