Synthesis of cyclic compounds consisting of face-to-face p-oligophenyls

Facile synthesis of xanthene-based π-stacked compounds consisting of face-to-face p-oligophenyls has been described. Just by mixing xanthene-4,5-diboronic acid and p-oligophenyls containing a benzenetetraol unit yielded cyclic compounds selectively due to the reversibility of the boronate esterification. In the ground state, weak π-π interactions between two p-oligophenyl moieties were observed, whereas their π-π interactions were clearly shown in the excited state.