A simple pillar[5]arene assembled multi-functional material with ultrasensitive sensing, self-healing, conductivity and host-guest stimuli-responsive properties.

Multi-functional materials have received wide attention due to their potential applications in various fields; therefore, developing a simple and easy strategy for the preparation of multi-functional materials is an interesting issue. In this work, a novel supramolecular gel, TP-QG, has been successfully constructed via the assembly of a simple methoxyl-pillar[5]arene host (TP) and a tripodal (tri-pyridine-4-yl)-amido-benzene guest (Q). Interestingly, TP-QG could act as a multi-functional material and showed strong fluorescence, good self-healing, host-guest stimuli-responsiveness and conductive properties. Due to these properties, TP-QG shows a fascinating application prospect. For instance, TP-QG could exhibit ultrasensitive fluorescence response for Fe3+ and F- in water via the fluorescence "ON-OFF-ON" pathway; the lowest detection limit (LOD) of TP-QG for Fe3+ was 2.32 × 10-10 M and the LOD of TP-QG-Fe for F- was 4.30 × 10-8 M. These properties permit TP-QG to act as not only a Fe3+ and F- sensor, but also an "ON-OFF-ON" fluorescence display material and an efficient logic gate. Meanwhile, the xerogel of TP-QG could remove Fe3+ from water, and the adsorption ratio was 98.68%; the xerogel of TP-QG-Fe could also remove F- from water; the removal ratio was about 87.92%. This work provides a feasible way to construct multi-functional smart materials by host-guest assembly.