1. Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes
- Author
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Schoder, Stefan, Schröder, Hendrik V., Cera, Luca, Puttreddy, Rakesh, Güttler, Arne, Resch-Genger, Ute, Rissanen, Kari, and Schalley, Christoph A.
- Subjects
Charge transfer ,Luminescence ,intramolecular motion ,cucurbiturils ,luminesenssi ,host–guest systems ,fluoresenssi ,supramolekulaarinen kemia ,fluorescence enhancement ,Biological materials ,Fluorophores - Abstract
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional conformational restriction of rotations around the aryl/aryl bonds. Because the cucurbituril complexes are pH switchable, this system represents an efficient supramolecular ON/OFF fluorescence switch. peerReviewed
- Published
- 2019