A bola-type supra-amphiphile constructed from a water-soluble pillar[5]arene and a rod-coil molecule for dual fluorescent sensing

A bola-type supra-amphiphile was successfully prepared and demonstrated to act as a dual fluorescent sensor. It was constructed from a water-soluble pillar[5] arene (WP5) and an imidazolium functionalized rod-coil molecule (1) driven by the WP5-imidazolium molecular recognition. Compared with the rod-coil molecule, the bola-type supra-amphiphile has strong fluorescence due to the influence of two bulky WP5 rings at its two ends, which can suppress the electronic coupling of the quinquephenyl aromatic rings, thus leading to the enhanced fluorescence. Thanks to the dual stimuli-responsiveness of the host-guest interactions, the fluorescence intensity of the bola-type supra-amphiphile was weakened by two types of signals, addition of paraquat and decrease in pH. Hence, this bola-type supra-amphiphile can serve as a paraquat sensor and a pH sensor.