Polyaromatic molecular tubes with a subnanometer pore and the guest-induced emission enhancement behavior.

New polyaromatic molecular tubes with a subnanometer pore (0.8 nm) were prepared. The tube bearing six sulfonate groups on the periphery and twelve methoxy groups at the openings provides a cylindrical hydrophobic cavity with a length of ∼1.3 nm. The aqueous tube can quantitatively bind one molecule of hydrocarbon guests in water with accompanying guest-induced emission enhancement (up to ∼3 times) of the host framework.