3IP-MAS-NMR

Fio. 42. 3IP, l3C, and H MAS NMR spectra of [ HsOHfeHbPWnO.,). Reprinted with permission from Ref. 169. Copyright 1992 American Chemical Society. 

The 3 Ip MAS NMR cross polarisation technique (CP) is useful to detect the presence of protons in the vicinity of the different P sites. These protons can be bound to framework oxygen atoms, or else can belong to water or organic template molecules filling the pores. The intensity of an 3ip CP MAS NMR signal is determined by the number of protons and their distance from the P atom. 

MAS NMR spectroscopy. Phosphorus modified ZSM-5 has been characterized using 3ip i94 27 ] 3ip NMR spectroscopy. ... 

Experimentally, the amount of sample required is determined by the sensitivity of the nucleus to be observed. Typically, mM of the sample (5-10 mg of lipid 0.5-1 mg of a small peptide 1-4 mg of a large protein) in a volume of about 0.7 mL or on 10-50 glass plates, may be needed for less sensitive ( H, i N) nuclei. For iR, 3ip and i C in MAS NMR, somewhat less material is required. Cross-polarization from the abundant proton magnetization may improve sensitivity, and decoupling (5-10 kHz for 80-100 kHz for H) is routinely used to improve spectral shape and reduce spectral widths. 

Later in this review, examples will be presented where rotor-synchronized H DQ MAS spectra provide both structural and dynamic insight. The method is, however, not restricted to H NMR, for example, 3ip 3ip pjQ MAS spectra of inorganic phosphates and glasses have also been presented.101 105 In addition, Nielsen et al. have presented a 13C-13C DQ MAS experiment,106 using which C—C connectivities of the alkyl backbone can be established, thus, allowing the... 

Fig. 2 a) 3ip CP/MAS and b) INADEQUATE ID NMR of c) the surface Au(I) species after reaction with an excess of PMes. Adapted with permission of the authors." ... 

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