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Strong Emission Enhancement in pH‐Responsive 2:2 Cucurbit[8]uril Complexes
Author(s) -
Schoder Stefan,
Schröder Hendrik V.,
Cera Luca,
Puttreddy Rakesh,
Güttler Arne,
ReschGenger Ute,
Rissanen Kari,
Schalley Christoph A.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201806337
Subject(s) - cucurbituril , intramolecular force , supramolecular chemistry , chemistry , photochemistry , fluorescence , aggregation induced emission , quenching (fluorescence) , photoluminescence , aryl , molecule , stereochemistry , materials science , organic chemistry , optoelectronics , physics , alkyl , quantum mechanics
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.