The structure of CHS was then characterized with various NMR techniques, i.e. one- (1D-) and two-dimensional (2D-) NMR, and FT Raman spectroscopy.
The established approach for this task consists in comparing the predicted NMR parameters, i.e., chemical shifts and coupling constants, with experimentally determined ones.
It is the only stable isotope with a non-zero spin; with a spin of 1/2, 195Pt satellite peaks are often observed in 1H and 31P NMR spectroscopy (i.e., Pt-phosphine and Pt-alkyl complexes).
We worked at low sample concentrations (about 300 400 μM) compared with the standard sample amounts used in biomolecular NMR spectroscopy (i.e., 1 mM).
Nineteen of these structures were discarded, as they did not agree with the Li NMR data (i.e., they involved the removal of one or more Li+ ion(s) from the Liα sublattice).
For these RNAs, two competing secondary structure folds with nearly degenerate free energies are almost equally populated, their interconversion rates being so slow as to give rise to distinct peaks in NMR spectra (i.e., the chemical shift separation is much larger than the interconversion rate).
The resonance NMR frequency, ν i, is then given by v i = (γ i /2π) Beff, where γ i is the magnetogyric ratio of the nucleus under observation.
Fig. 2 a 1H NMR spectra of (I) Pluronic-PEI and (II) Pluronic-PEI-DR5-TAT. b IR spectra of (I) Pluronic-PEI and (II) Pluronic-PEI-DR5-TAT. c Degradation of Pluronic-PEI-DR5-TAT after incubation with buffer at 37 °C.
Lyophilized BiNPs, glucose, and PPD (250 μL) were separately dissolved in 750 μL of D2O (Cambridge Isotope Laboratories, 99.9%), and H NMR spectra were obtained on a Bruker 600 MHz AVANCE-III Nuclear Magnetic Resonance (NMR) spectrometer using a standard pulse sequence (Zg30).
