Control of intramolecular excimer emission in luminophore-integrated ionic POSSs possessing flexible side-chains

Abstract

Polycyclic aromatic hydrocarbons such as naphthalene, anthracene and pyrene were integrated onto polyhedral oligomeric silsesquioxanes (POSSs) having flexible ionic linkers and their luminescence properties were evaluated. Initially, significant excimer emissions were observed from the diluted solutions including each modified POSS. It was found that excimer formation around the POSS unit was facilitated by connecting to the rigid core via the flexible linkers. In particular, the luminescence properties were drastically changed depending on the solvent polarity. It was indicated that the spatial distances between the side-chains can be regulated by introducing ionic groups into the side-chains. Furthermore, the luminescence properties in aqueous solution of the modified POSSs were controllable by adding amphiphilic anions and polyanionic compounds. Finally, this system was applied for the detection of sodium dodecyl sulfate (SDS) which is the conventional indicator of river pollution. These data indicate that intramolecular interaction between the side-chains around the POSS was dynamically controlled by environmental factors. Consequently, stimuli-responsive luminescent materials were obtained.