Solid-state NMR and computational chemistry study of mononucleotides adsorbed to alumina

Solid-state NMR spectroscopy and ab initio computational chemistry are used to determine the structure of the complex formed upon adsorption of the mononucleotide 2'-deoxyadenosine 5'-monophosphate (dAMP) to the surface of a mesoporous alumina. In this multi-technique approach, rotational-echo double-resonance NMR results reveal that the phosphate group of dAMP interacts predominantly with octahedrally coordinated aluminum species at the surface, and therefore, adsorption is modeled with both mono- and bidentate sorption of the nucleotide phosphate group with octahedral aluminum. 31P chemical shielding tensors are calculated from the structure of the lowest energy conformations, and these results are compared to tensor values extracted from analysis of spinning-sideband patterns in the experimental 31P cross-polarization magic-angle-spinning NMR spectrum. The chemical shift anisotropy and asymmetry parameter indicate that the binding is via a monodentate, inner-sphere complex.