NMR of Model Compounds

Model compounds with well-defined chemical compositions and structures are indispensable for any study of biominerals or biomineralization processes. The solid-state NMR parameters of selected model compounds 

Consider the 31P 1H CP dynamics of monetite and brushite, both of their tcp values (see Equation (1)) are more or less the same,16 showing that the 1H-31P dipolar interaction within the HP042 species dominates the polarization transfer.82 On the other hand, the Tip value of monetite is considerably longer than that of brushite. 

The squares, representing the experimental data, are larger than the error bars. 

The simulations correspond to different spin clusters containing 2-7 phosphorus spins. The geometrical parameters were taken from the X-ray structure of HAp. 

For the samples of CHAp-A prepared by high temperature treatment (900 °C) of HAp in CO2 atmosphere, the 13C MAS spectrum would have a sharp resonance at 166.5 ppm with a full width at half maximum (FWHM) of about 1 ppm.88 Interestingly, a total of four peak components was found in the 31P MAS spectrum, ranging from 2.5 to 5.5 ppm 31 For the samples of CHAp-B prepared by wet chemistry at 80 °C and those of CHAp-AB prepared by thermal crystallization of carbonated ACP at 500—600 °C, both of their 13C MAS spectra contain peak components 

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