Strong Emission Enhancement in pH‐Responsive 2:2 Cucurbit[8]uril Complexes

Abstract

Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications,b ut frequentlyl imited by aggregation-a nd rotation-caused photoluminescence quenching. As eries of easily accessible bipyridinium fluorophores, whose emission is quenched by at wisted intramolecular charge-transfer (TICT) mechanism,i sr eported. Encapsulationi nacucurbit[7]urilh ost gave a1 :1 complex exhibiting am oderate emissioni ncreased ue to destabilization of the TICT state inside the apolar cucurbituril cavity.Amuch stronger fluorescence enhancement is observed in 2:2c omplexes 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.

Modular supramolecular dimerization of optically tunable extended aryl viologens

“…S75†). 18 A similar observation of enhanced photoluminescence for 2 : 2 complexes of CB[8] and viologen derivatives was recently described 19,20…”

Controlling the structure and photophysics of fluorophore dimers using multiple cucurbit[8]uril clampings

“…Although individual cases have demonstrated photophysical changes upon complexation with CB [8], 31,35,39,[44][45][46][47] the beauty and power of this work stems from the simple modular design. As illustrated in Fig.…”

“…a molecule with signicant rigidity. 28,29 For instance, various rigid molecular moieties such as benzidine, 30 benzothiazole, 31,32 arylpyridinium, 28,33 arylterpyridyl, 34 bipyridinium, 35 and benzimidazole 29 have been employed to produce CB[8]-mediated 2 : 2 complexes. Herein, we present a general and modular strategy towards the dimerization of arbitrary functional components (uorophores in this work) by connecting them to multiple rigid modules that can be "clamped" together by CB [8] complexation.…”

Tunable Fluorescence-Responsive Double Hydrophilic Block Polymers Induced by the Formation of Pseudopolyrotaxanes with Cucurbit[7]Uril

“…In contrast, the supramolecular approach offers a convenient and low-cost strategy for smart luminescent materials, because the photophysical properties can be tuned by varying the non-covalent interactions [39]. Recently, supramolecular approaches, such as host-guest interaction, have been widely used to suppress ACQ [40,41,42]. Supramolecular smart materials based on host-guest interactions have become increasingly popular [43,44,45,46].…”