The use of cucurbit8uril as a molecular host has emerged in the chemical literature as a reliable strategy for the creation of dynamic chemical systems, owing to its ability to form homo‐ and ...heteroternary complexes in aqueous media with appropriate molecular switches as guests. In this manner, CB8‐based supramolecular switches can be designed in a predictable and modular fashion, through the selection of appropriate guests able to condition the redox, photochemical, or pH‐triggered behavior of tailored multicomponent systems. Furthermore, CB8 allows the implementation of dual/triple and linear/orthogonal stimuli‐dependent properties into these molecular devices by a careful selection of the guests. This versatility in their design gives these supramolecular switches great potential for the rational development of new materials, in which their function is not only determined by the custom‐made stimuli‐responsiveness, but also by the transient aggregation/disaggregation of homo‐ or heteromeric building blocks.
Switch that: The capability of cucurbit8uril as a molecular host to form homo‐ and heteroternary complexes in aqueous media has fueled its use in supramolecular switches. The use of those dynamic systems is especially interesting since they can be reversibly transformed by the application of external stimuli, such as light, redox potential, or pH, and even allow the implementation of orthogonal stimuli responsiveness.
A supramolecular double network hydrogel is presented by physical interpenetration of DNA and cucurbit8uril networks. In addition to exhibiting an increase in strength and thermal stability, the ...double network hydrogel possesses excellent properties such as stretchability, ductility, shear‐thinning, and thixotropy. Moreover, it is enzymatically responsive to both nuclease and cellulase, as well as small molecules, showing great potential as a new soft material scaffold.
Host-guest complexes exhibiting a 1 : 1 binding stoichiometry need not consist of a single host and guest. A series of oligopeptides, which were previously reported to have abnormally high binding ...enthalpies were investigated to deduce whether they exist as a 2 : 2 quaternary or a 1 : 1 binary complex with cucurbit8uril (CB8). Through a systematic study of the sequence-specific binding pathways of peptide-CB8 association, a phenylalanine-leucine dipeptide was found to be capable of switching from a 1 : 1 stoichiometric complex to a 2 : 1 complex. By studying the differences in size-based diffusion properties of these two binding modes, the presence of a 1 : 1 pairwise inclusion complex was verified for the regime where CB8 is in excess. Findings in this study can be utilised to 'customise' the precise CB8-oligopeptide self-assembly pathway, acting as a useful toolbox in the design of supramolecular systems.
Supramolecular organic frameworks (SOFs) are widely used for biological detection and drug delivery. In this study, a SOF system was fabricated through the self-assembly of photosensitive ...triarylboron (TAB), TAB-6-methyl, and CB8. The maximum fluorescence emission of TAB-6-methyl was greatly enhanced and red-shifted from 560 nm to 610 nm after SOF formation. The SOF can specifically respond to a microRNA by dissembling and then combining with microRNA, which is accompanied by a fluorescence shift from 610 nm to 560 nm, thus providing a ratiometric readout for microRNA detection. The photosensitivity of TAB-6-methyl can be further improved by forming a SOF, which can be used in photodynamic therapy. By constructing another guest molecule, TAB-5-1-cRGD, we successfully embedded cRGD in the SOF system to improve its tumor-targeting ability. Moreover, we used this SOF system as a fluorescence imaging probe for targeted tumor imaging and as a drug carrier system for loading DOX to achieve combined photodynamic and chemotherapy treatment of tumors.
Pentapeptides containing a Phe residue in the middle of the sequence exhibit ternary complex formation in the presence of cucurbit8uril, thus opening new perspectives on supramolecular peptide ...dimerisation studies.
Ammonia (NH3) and hydrazine (N2H4) are both utilized within a wide range of chemical industry, agriculture and pharmaceuticals. A detection strategy is realized for the identification of gaseous NH3 ...and N2H4, adopting the host-guest complexation between AIE-active molecule TPM and cucurbit8uril (CB8). The TPM@CB8 complex exhibits a deep red emission, which is immediately turned into light yellow and sky-blue as meeting with gaseous NH3 and N2H4, respectively. This newly reported TPM@CB8 complex is capable of sensitively and selectively detecting gaseous NH3 and N2H4 with a low detection limit (0.80 ppm and 0.41 ppm). The sensing mechanism is studied with 1H NMR, HRMS, SEM and DFT calculations. Finally, TPM@CB8 complex could detect N2H4 vapor from real water samples, and act as a food spoilage sensor for monitoring gaseous NH3 generated in food spoilage.
A novel host-guest complex TPM@CB8 formed between AIEgen TPM and CB8 has been reported, which exhibited the dual fluorescence response toward gaseous N2H4 and NH3 on glass plate. Display omitted
•A novel host-guest complex TPM@CB8 was explored.•This complex could simultaneously sense gaseous NH3 and N2H4 on glass plate.•The sensing sensitivity of this complex was much higher than most other probes.•This complex was able to detect gaseous NH3 and N2H4 in real samples.
This study reports the results of binding free energy calculations for CB8 host–guest systems in the SAMPL6 blind challenge (receipt ID 3z83m). Force-field parameters were developed specific for each ...of host and guest molecules to improve configurational sampling. We used quantum mechanical (QM) implicit solvent calculations and QM force matching to determine non-bonded (partial atomic charges) and bonded terms, respectively. Free energy calculations were carried out using the double-decoupling method (DDM) combined with Hamiltonian replica exchange method (HREM) and Bennett acceptance ratio (BAR) method. The root mean square error (RMSE) of the predicted values using DDM with respect to the experimental results was 4.32 kcal/mol. The coefficient of determination (R
2
) and Kendall rank coefficient (
τ
) were 0.49 and 0.52, respectively, highest of all submissions. In addition, these were compared to the results obtained by umbrella sampling (US) and weighted histogram analysis method (WHAM). Overall, DDM achieved a higher prediction accuracy than the US method. Results are discussed in terms of parameterization and free energy simulations.
Reversible 2D supramolecular organic frameworks encompassing branched viologen architectures and cucurbit8uril (CB8) were constructed and investigated. UV-vis investigation clearly indicates the ...formation and intermolecular dimerization of monocation radicals and their encapsulation into the hydrophobic CB8 cavity which is further complemented by EPR (electron paramagnetic resonance) spectroscopy. Particle size measurements by dynamic light scattering method showed particle sizes in the range of several µm indicating larger aggregates. Zeta potential measurements suggested the instability of these particles and their tendency to form aggregates. TEM (transmission electron microscope) analysis further revealed the formation of supramolecular polymer (monocation radical with cucurbit8uril) whose diameter were in the range of several µm as indicated by DLS measurements; however the oxidized form, i.e., the viologen dication with cucurbit8uril showed dotted spots in the range of sub nanometer level. The internal periodicities of the supramolecular polymers were analyzed by SAXs (small angle X-ray scattering) measurements. Additionally, we have demonstrated that these supramolecular organic frameworks can be depolymerized by oxidation in air and again can be polymerized (intermolecular radical dimerization) by reduction under inert atmosphere demonstrating that these systems will be of broad interest.
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![Oligopeptide-CB[8] complexa...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1477-0520_1477-0539/small "Oligopeptide-CB[8] complexation with switchable binding pathways")
![AIEgen@CB[8] complex as rat...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0925-4005/small "AIEgen@CB[8] complex as ratiometric fluorescent probe for dual-response of gaseous ammonia and hydrazine with different emission channels")
![Prediction of CB[8] host–gu...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0920-654X_1573-4951/small "Prediction of CB[8] host–guest binding free energies in SAMPL6 using the double-decoupling method")
