A Variable Temperature Study of the π–π Stacking Interaction in the Co-Crystal Naphthalene-Octafluoronaphthalene

Introduction: The structure of the 1:1 co-crystal of naphthalene and octafluoronaphthalene, which has been previously determined at room temperature, was determined at 100, 150, 200 and 250 K. Results: Reductions in intermolecular distances and unit cell dimensions are observed on cooling. DFT calculations reveal that the energies of interaction between pairs of molecules vary little with temperature. Conclusion: The strongest interaction is the π–π stacking between virtually parallel naphthalene and octafluoronaphthalene molecules and this displays less change with temperature than the other, weaker, interactions, which have much shallower energy minima.