Growth and spectroscopy studies of ADP single crystals with l-glutamine and l-cysteine amino acids

Abstract

Ammonium dihydrogen orthophosphate (ADP) crystals were grown with l-glutamine C5H10N2O3 (gln) and l-cysteine C3H7NO2S (cys) amino acids, with polar side-chains, as additives at 4% molar concentrations. X-ray diffractograms, vibrational FT-IR, and Raman and NMR MAS of 31P, 1H and of pure and treated compounds were recorded at room temperature and interpreted. A lift of degeneracies of the ν4 asymmetric bending modes of both PO4 and NH4 tetrahedron species, as well as a shift of the wavenumbers of some of their internal modes was observed. At the same time, some characteristic vibrational modes of the organic molecules appeared. However, NMR results show a little shift of the resonance of the phosphorus and hydrogen nucleus, associated with some shoulders for this latter. The presence of the organic molecules was also revealed by 13C MAS NMR. These observations indicate that the host-additives interactions were achieved.