OEGylated cyclodextrin-based thermoresponsive polymers and their switchable inclusion complexation with fluorescent dyes

Using oligo(ethylene glycol)s (OEG)-modified beta-cyclodextrin (CyD) as the building block, a new class of thermoresponsive polymers carrying CyD pendants with switchable inclusion ability are reported. Their synthesis, thermoresponsive behaviour and host-guest chemistry are described. Similar to other OEG-based polymers, these CyD polymers exhibit characteristic thermoresponsive properties. Their thermoresponsiveness and complexation behaviour are compared with their corresponding monomers to demonstrate the macromolecular effect. Notably, OEG moieties are found to cooperatively participate in the inclusion complexation with fluorescent dyes (guests). This cooperative interaction results in strong induced circular dichroism and significantly fluorescence enhancement from the guest dyes. These encapsulated guest dyes can be easily released at elevated temperature, associated with obvious fluorescence quenching, which makes these CyD polymers ideal candidates as scaffolds for thermoresponsive fluorescent sensors.