Thiapillar[5]arenes: Structures, Properties, and Host-Guest chemistry

Abstract

The chemical modification of bridging groups of the pillar[n]arenes is an important way to functional derivatization and expand the application fields. So far, however, there have been few reports on this issue. On the basis of experimental reports, a series of thiapillar[5]arene structures with sulfur, sulfoxide and sulfone as bridging groups are proposed in this work. By using density functional theory (DFT) calculations, thiapillar[5]arenes are studied systematically at the ωB97XD/6-311G(d,p) level of theory. All the structures have regular pentagonal shape with the point group of D5. The substitution of bridging methylene by sulfur leads to a significant enlargement in the molecular cavity, an extension of the spatial delocalization of the electrons, and a redshift of the absorption spectrum. The bridging groups of sulfoxide and sulfone can greatly improve the solvent effects in polar solvents, which is followed by the weakening of the pi-electron donating capacity inside the molecular cavity. Thiapillar[5]arenes have rich host–guest chemistry and can recognize a variety of guest species. Interestingly, the inclusion of thiapillar[5]arenes to ferrocene is a synergistic result of electronic and spatial effects. The sulfur-containing derivatizations of pillar[n]arenes are expected to expand the application prospects in supramolecular biology and electrochemistry related fields.