Host-Assisted Aggregation-Induced Emission of a Tetraphenylethylene Derivative and Its Responses toward External Stimuli

Aggregation-induced emission (AIE) of fluorogenic dyes offers many opportunities as smart materials, fluorescence sensing of analytes, bioimaging, molecular electronics, and many others. AIE dyes (called AlEgens) produce emission through aggregation, which are more advantageous than conventional emission of monomeric fluorophores, as the latter is unduly susceptible toward various quenching processes. Here, we report AIE enhancement of a polyanionic sulfonato-tetraphenylethylene (SuTPE) derivative, achieved through supramolecularly assisted dye aggregation, as SuTPE interacts with a multicationic amino-beta- cyclodextrin (A beta CD) host. Aggregation of the dye is induced mainly because of strong electrostatic interaction of SuTPE with A beta CD, causing a significant extent of charge neutralization for the polyanionic dyes, helping their assemblage at the multicationic host portal. Job's plot studies suggest preferential formation of 2:1 dye-to-host stoichiometric complexes in the present system. Ionic-strength-dependent studies nicely support the involvement of electrostatic interaction in the present system through salt-induced disintegration of the SuTPE-A beta CD complexes. The AIE enhancement for the SuTPE-A beta CD system is very sensitive to the external stimuli, such as pH and temperature, suggesting its prospects in various stimuli-responsive applications. Furthermore, the SuTPE-A beta CD system can suitably quantify an important bioanalyte, ATP, following a competitive binding strategy, suggesting its potential application as a supramolecular biosensor.

Automated summary

Aggregation-induced emission (AIE) of fluorogenic dyes provides various opportunities in smart materials, fluorescence sensing, bioimaging, and molecular electronics. The enhancement of AIE in the SuTPE-AβCD system is achieved through supramolecularly assisted dye aggregation, showing high sensitivity to external stimuli and potential application as a supramolecular biosensor.