Triple emission from p-dimethylaminobenzonitrile-cucurbit[8]uril triggers the elusive excimer emission.

The intriguing dual-emission behavior of p- dimethylaminobenzonitrile (DMABN) and the identity of the associated excited states is, arguably, the most extensively investigated and also controversially discussed molecule- specific phenomenon of modern photochemistry. We have now found a new, third fluorescence band when DMABN is encapsulated within the water-soluble molecular container cucurbit[8]uril (CB8). It is centered between the previously observed emissions and assigned to the elusive excimer emission from DMABN through 1:2 CB8:DMABN complex formation.

Release of high-energy water as an essential driving force for the high-affinity binding of cucurbit[n]urils.

Molecular dynamics simulations and isothermal titration calorimetry (ITC) experiments with neutral guests illustrate that the release of high-energy water from the cavity of cucurbit[n]uril (CBn) macrocycles is a major determinant for guest binding in aqueous solutions. The energy of the individual encapsulated water molecules decreases with increasing cavity size, because larger cavities allow for the formation of more stable H-bonded networks. Conversely, the total energy of internal water increases with the cavity size because the absolute number of water molecules increases.

A photoinduced pH jump applied to drug release from cucurbit[7]uril.

A proof-of-principle for the application of a photoinduced pH jump for delivery of the Hoechst 33258 drug by disassembly of its host-guest complex with cucurbit[7]uril is described.

Supramolecular logic with macrocyclic input and competitive reset.

The fluorescence of a designed water-soluble 4-sulfonato-1,8-naphthalimide dye can be switched on by the synchronous host-guest complexation with cucurbit[7]uril and decrease in pH (from 9 to 7). This affords a dual resettable (by addition of cadaverine as competitor or by deprotonation) logic gate based on modulation of photoinduced electron transfer.

Toxicity of cucurbit[7]uril and cucurbit[8]uril: an exploratory in vitro and in vivo study.

Cucurbit[n]urils (CB[n]) are potential stabilizing, solubilizing, activating, and delivering agents for drugs. The toxicity of the macrocyclic host molecules cucurbit[7]uril (CB[7]), the most water-soluble homologue, as well as cucurbit[8]uril (CB[8]) has been evaluated. In vitro studies on cell cultures revealed an IC(50) value of 0.

Salt-induced guest relocation from a macrocyclic cavity into a biomolecular pocket: interplay between cucurbit[7]uril and albumin.

The binding affinity of Neutral Red with cucurbit[7]uril (CB7) can be fine-tuned by addition and competitive binding of metal ions, which leads also to a pK(a) shift of the dye; this can be exploited to relocate the dye from the macrocyclic cavity of CB7 to the biomolecular pocket of bovine serum albumin.

Supramolecular tandem enzyme assays for multiparameter sensor arrays and enantiomeric excess determination of amino acids.

The coupling of an enzymatic transformation with dynamic host-guest exchange allows the unselective binding of macrocycles to be used for highly selective analyte sensing. The resulting supramolecular tandem enzyme assays require the enzymatic substrate and its corresponding product to differ significantly in their affinity for macrocycles, for example, cation receptors, and to show a differential propensity to displace a fluorescent dye from its host-guest complex. The enzymatic transformation results in a concomitant dye displacement that can be accurately followed by optical spectroscopy, specifically fluorescence.