A clusteroluminescent supramolecular polymer network constructed by pillararene and its application in information encryption

Clusterization-triggered emissive (CTE) materials have attracted great attention in recent years. The regulation of the emission property of materials with CTE property through supramolecular interactions is an excellent strategy for the construction of smart fluorescent materials. In this work, we have prepared a regulatable supramolecular polymer network with CTE properties through pillararene-based host−guest interactions. The pillar[5]arene-grafted poly(methyl methacrylate) (PMMA) showed a classic CTE character. After adding Brooker's merocyanine-grafted polymer to the solution of the pillar[5]arene-containing PMMA, the supramolecular polymer network gel formed by the host−guest interactions between pillararene and Brooker's merocyanine guest. This supramolecular network showed brighter fluorescence than the pillar[5]arene-grafted PMMA in the solid state. In addition, the fluorescence emission of the supramolecular network can be further regulated by pH conditions. After adding an acid, the Brooker's merocyanine-containing guest polymer was protonated, and the supramolecular network changed to a protonated network through host−guest interactions between protonated Brooker's merocyanine guest and pillararene. Interestingly, the fluorescence was quenched when the supramolecular network turned into the protonated network. After adding a base, the protonated network can convert back to the original network, along with recovery of the fluorescence. Therefore, the regulation of the fluorescence of the supramolecular polymer materials with CTE was successfully realized by pillararene-based host−guest interactions. Furthermore, this tailorable fluorescent supramolecular polymer network system was applied as an information encryption material.