A ⁴³ Ca nuclear magnetic resonance perspective on octacalcium phosphate and its hybrid derivatives

43Ca nuclear magnetic resonance (NMR) spectroscopy has been extensively applied to the detailed study of octacalcium phosphate (OCP), Ca8(HPO4)2(PO4)4.5H2O, and hybrid derivatives involving intercalated metabolic acids (viz., citrate, succinate, formate, adipate). Such phases are importance in development a better understanding bone structure. High-resolution magic angle spinning (MAS) experiments, including double-rotation (DOR) NMR, as well 43Ca{1H} rotational echo DOR (REDOR) 31P{43Ca} REAPDOR NMR spectra, were recorded on 43Ca-labeled OCP phase at very high field (20 T), complemented by ab initio calculations parameters using Gauge-Including Projector Augmented Wave–density functional theory (GIPAW-DFT) method. This enabled partial assignment eight inequivalent Ca2+ sites OCP. Natural-abundance MAS spectra then for organic–inorganic derivatives, revealing changes lineshape. In case citrate derivative, these could be interpreted basis computational models Overall, this highlights advantages combining high-resolution experiments modeling studying complex biomaterials.