Fitting the 31 P NMR spectra of the pristine glass yielded (Figure ). peaks at -26.4 ppm and (seen as a shoulder in the spectra) at -36.3 ppm (Table ). The main peak of the pristine glass at -26.4 ppm corresponds to phosphorus in a Q 2 unit, which contains two bridging oxygen atoms (Figure inset) and is a plausible site for coordination to metal ions such as zinc. This peak displays a shift towards less negative ppm values when agZIF-62 is added to the blends. Previous reports on Na2O-ZnO-P2O5 glasses indicate that the presence of Zn centres can induce a shift in the Q 2 signal of the 31 P NMR spectra and more generally, the chemical shift of 31 P nuclei is sensitive to the modifier cations bonded to the non-bridging oxygen atoms. The peak shift in the blend samples could be indicative of a potential P-O•••Zn interaction.