First principles calculations of NMR parameters in biocompatible materials science:: The case study of calcium phosphates, β- and γ-Ca(PO3)2. combination with MAS-J experiments

First principles calculations (FPC) of NMR parameters in biocompatible materials science were used to study the spectra related to β and γ-calcium phosphates with magic angle spinning (MAS) technique. β group is found to exhibit zigzag chains arranged in a unidirectional manner throughout the entire structure, whereas γ group shows criss-cross arrangement of helical chains. A good agreement is obtained between the experimental and the calculated data for both isotropic chemical shift and chemical shift anisotropy of the calcium phosphate groups. The results also show a strong off-diagonal correlations corresponding to J-coupled nuclei of the two calcium phosphates. The usefulness of the combination of ab inito calculations and 2D NMR experiments is clearly demonstrated in these calcium phosphates, as they present similar characteristics.