At higher temperature, the jumps between different Al atoms lead to a drastic increase in the RMSD values. While the formation of Al-F bonds occurs in both AlPO4-AST_TMA and AlPO4-AST_QNU, the nature of the OSDA has a pronounced effect on the direction of fluoride displacements: In the TMA-containing system, the displacement pattern is random, without detectable preference for any of the four available Al atoms (Figure ). The situation is different in AlPO4-AST_QNU, where fluoride anions are preferentially bonded to the Al atom neighbouring the oxygen atom that acts as hydrogen bond acceptor. This preference is almost perfectly realised at 150 and 298 K (Figure ).