Advance 2 400 mhz

LEU acetate and LFCs were dissolved in deuterated DMSO (DMSO-d6) at a concentration of 20 mg/mL. ¹H-NMR spectra were analyzed using a Bruker ADVANCE II 400 MHz spectrometer at 25 °C.

AMP (purity: ≥99%; Chemical Abstracts Service no. 115-69-5) samples were purchased from Sigma-Aldrich. A partially deuterated sample was prepared by replacing the hydrogen atoms associated with the N and O sites via secondary deuteration using D₂O (99.9 atom % D, Sigma-Aldrich). A total of 4 g of the sample was added to a flask containing 3.6 mL of D₂O (99.9 atom % D, Sigma-Aldrich). The flask was then sealed and stirred at 313 K for 48 h. Thereafter, it was heated at 383 K for 2 h while purging with pure N₂ gas (99.999%) to remove the solvent D₂O. The sample, together with the flask, was then frozen at ∼254 K in a refrigerator for 2 h, after which it was purified for 1 h on a Schlenk vacuum line at room temperature to remove the residual D₂O. The fine powders were again dried for 1 h on a Schlenk vacuum line at room temperature. The as-obtained product was again deuterated to enhance the purity. The final deuterated ratio of ∼28.6% was determined through proton nuclear magnetic resonance (Advance II-400 MHz, Bruker; solvent: DMSO-d6).