Flip angles and field homogeneity of the field-cycling NMR and MRI unit (Terra-Nova, Magritek, NZ) were adjusted according to the MR signal of a water sample that was prepolarized for 4 s at 20 mT. For hyperpolarization experiments, fresh pH2 was supplied for every acquisition to the headspace of the reaction chamber.
According to 13C NMR spectra, polar units were located both on the main chain and at the chain end.
The percentage methacrylation efficiency, E f, was estimated using NMR, assuming seven units of propylene glycol in each molecule and the following equation, to be 91%: % E f = PPG/MA obt PPG/MA exp × 100 PPG/MA obt and PPG/MA exp are the obtained and expected propylene glycol/methacrylate ratio, respectively.
Patterson searches were made to determine the orientation and position of the NMR structures in the unit cell.
In addition it is evident that N-C-Ar carbon, in all cases, is more deshielded as compared to N-C-R carbon due to being sandwiched by two electron withdrawing groups because N-C-R group is attached to electron withdrawing and donor groups (Figure 4). Figure 4 Relative deshielding of methylene groups, attached directly to benzimidazolium units in NMR spectroscopy.
The regions used for the integration of the different acetylated structural units (H NMR and C HMBC spectra) are shown in Figure 4.
The microstructure of the main product was surmised from the peak integration of in situ FT-IR spectra, the intensity of each repeating unit on 13C NMR spectra and the number average molecular weight.
While further data, including dynamics for [P12W]-species that retain the P17,18,19 unit based on NMR probes within that unit, are required to fully clarify the nature of the contacts made by Trp12 in the folding transition state, the present study does provide insights.
Sample temperature was controlled by a VT unit on the NMR spectrometer to 27 ± 1 °C.
