With the exception of the F-N RDF of AlPO4-AST_TMA, which will be addressed separately below, atoms. If such bonds were present, it would be reasonable to expect an elongation of the H-O distance with increasing temperature, as increased thermal motion should weaken and -at sufficiently high temperature -break the bonds. The observation of shorter, rather than longer H-O distances upon increasing temperature provides no evidence for the presence of hydrogen bonds, indicating instead that non-directional interactions dominate. for GeO2-AST_QNU (Figure ). The F-N RDF obtained for 150 K shows four distinct maxima, which correspond to the distances from a given fluoride anion to the nitrogen atoms belonging to QNU cations in the four surrounding ast cages (Figure ). With increasing temperature, the four maxima become increasingly blurred, leading to a single broad maximum with a poorly developed substructure at 573 K. The broadening of the F-N RDF is considerably more pronounced than that of the F-Ge RDF (Figure ), which can be attributed to the increased thermal motion of the OSDA cations. This is corroborated when looking at the H-O RDFs: At 150 K, there is a distinct first maximum centred at ~1.7 Å, together with a second, smaller maximum centred at ~2. indicates that the hydrogen bonds are weakened, and eventually broken, due to more vigorous movements of the QNU cations. Once the hydrogen bonds are broken, the OSDA molecules are prone to reorient within the ast cages. Indeed, the visualisation of representative last AIMD frames obtained for SiO2-AST_QNU and GeO2-AST_QNU (for T = 573 K) shows that several QNU cations have changed their orientation with respect to their perfect ordering in the starting structures (Figure ). Given the impact of framework-OSDA interactions on the ordering of pyritohedral distortions in GeO2-and GaPO4-AST_QNU, and on the ordered displacements of fluoride anions in AlPO4-and GaPO4-AST_QNU, it is straightforward to link the reorientation of some QNU cations to a reduced degree of ordering at 298 K and, especially, 573 K. The pronounced orientational disorder of the OSDA in the experimental crystal structures of SiO2-AST_QNU and AlPO4-AST_QNU (AlPO4-16), obtained at room agrees with these AIMD results. Finally, it is worth taking a separate look at the F-N RDFs of AlPO4-AST_TMA and AlPO4-AST_QNU.