The role of the ethynyl substituent on the π-π stacking affinity of benzene: a theoretical study

Herein, we report a high-level theoretical study (SCS-RI-MP2(full)/aug-cc-pVTZ) examining the stacking affinity of 1,3,5-triethynylbenzene. The stacking properties of this compound are compared to those of benzene and 1,3,5-trifluorobenzene. The results indicate that the ethynyl substituent improves the stacking affinity of the arene, since the binding energies for the stacked ethynyl-substituted arene dimers are higher than those of both benzene and the fluoro-substituted arene. This interesting behaviour has been studied by examining the energetics, geometries and electron charge density features of the complexes. A query in the Cambridge Structural Database returned several X-ray crystal structures containing π-π stacking interactions of 1,3,5-triethynylaryls that strongly agree with the theoretical results.