A newly supramolecular catalytic system: the supramolecular self-assembly of Rh8 cages host anthracene molecules for [4+4] cycloaddition induced by UV irradiation

Supramolecular assembly, used as molecular reactors, is of great significance in host-guest chemistry. In this work, we used a tetratopic pyridyl ligands as a building block to hierarchically combine a slightly twisted cuboid with half-sandwich rhodium fragments. The cuboid directionally self-assembled hydrophobic pockets that can encapsulate conjugated molecules like anthracene (ANT) as guests in solution, by supramolecular interactions including Hydrgen bonding and hydrophobic interactions. The array of the ANT molecules in the confined pockets was permitted [4+4] photocycloaddition reaction under UV light as external stimulus in methanol solution. And further, the proposed mechanism of the process was given. The cuboid was fully characterized by 1H NMR, single crystal X-ray diffraction (SCXRD), and mass spectrometer (MS), and its host-guest and cycloaddition processes were monitored by 1H NMR and UV- visible spectrophotometer.