Complexation of Triptycene-Based Macrotricyclic Host toward (9-Anthracylmethyl)benzylammonium Salt: A Ba²⁺ Selective Fluorescence Probe

A new triptycene-based macrotricyclic host containing two dibenzo-30 crown-10 moieties (1) has been synthesized. It could form a 1:2 stable complex 1·32 with (9-anthracylmethyl)benzylammonium salt (3) in both solution and solid state, in which the 9-anthracyl groups were selectively positioned inside the cavity of the host. Moreover, the complexation and disassociation of complex 1·32 could be chemically controlled by the addition of base and acid. It was also found that Ba2+ ion could considerably induce the fluorescence enhancement of complex 1·32, which might thus be utilized as a selective supramolecular fluorescence probe for Ba2+ ion. Fluorescence and 1H NMR spectroscopic titrations further showed that the complexation between complex 1·32 and barium ions underwent a two-step process.