Synthesis of a symmetrical octamethyl-substituted cucurbituril with a dimethyl-substituted glycoluril dimer

Cucurbit[n]uril-Based Supramolecular Frameworks Assembled through Outer-Surface Interactions

Porous materials, especially metal-organic frameworks, covalent organic frameworks, and supramolecular organic frameworks, are widely used in heterogeneous catalysis, adsorption, and ion exchange. Cucurbit[n]urils (Q[n]s) suitable building units for porous materials because they possess cavities with neutral electrostatic potential, portal carbonyls with negative electrostatic potential, and outer surfaces with positive electrostatic potential, which may result in the formation of Q[n]-based supramolecular frameworks (QSFs) assembled through the interaction of guests within Q[n]s, the coordination of Q[n]s with metal ions, and outer-surface interaction of Q[n]s (OSIQ). This review summarizes the various QSFs assembled via OSIQs. The QSFs can be classified as being assembled by 1) self-induced OSIQ, 2) anion-induced OSIQ, and 3) aromatic-induced OSIQ. The design and construction of QSFs with novel structures and specific functional properties may establish a new research direction in Q[n] chemistry.

Supramolecular chemistry of substituted cucurbit[n]urils

This review covers important advances in the field of substituted cucurbit[n]urils.

The lanthanide contraction effect and organic additives impact the coordination structures of lanthanide ions with symmetrical octamethyl-substituted cucurbit[6]uril ligands

Two facts, the lanthanide contraction effect and the “bridge” role of organic additives, impact the coordination structures of lanthanide ions with OMeQ[6] ligands.

Synthesis and separation of cucurbit[n]urils and their derivatives

Cucurbit[n]uril chemistry has become an important part of contemporary supramolecular chemistry since cucurbit[n]urils (Q[n]s) are not only able to encapsulate various guests, but are also capable of coordinating to a wide range of metal ions, leading to the establishment of Q[n]-based host-guest chemistry and coordination chemistry. Each of these impressive developments can be attributed to the growth of protocols for obtaining Q[n]s. In this review, we survey synthetic procedures for obtaining cucurbit[n]urils and their substituted derivatives together with the separation and purification of these remarkable compounds. The coverage is aimed at both existing workers in the field as well as at those requiring an "entry" into Q[n]-based research.

Novel nano-size and crab-like biological-based glycoluril with sulfonic acid tags as a reusable catalyst: its application to the synthesis of new mono- and bis-spiropyrans and theirin vitrobiological studies

Herein novel crab-like biological-based glycoluril with sulfonic acid tags was prepared in nano-size form and fully characterizedviaseveral techniques.

Adducts of aqua complexes of Ln3+ with a di-hydroxylated symmetrical octamethyl-substituted cucurbituril: potential applications for isolation of heavier lanthanides

In the present work, we have demonstrated that t(OH)₂OMeQ[6] could be used for isolating heavy lanthanides from their lighter counterparts.

Coordination and supramolecular assemblies of mono-hydroxylated octamethylcucurbit[6]uril with alkali and alkaline earth metal ions in the presence of polychloride cadmium anions

The interactions of alkali metal and alkaline earth metal cations with (OH)OMeQ[6] have been investigated with polychloride cadmium anions as structure-directing agents.

Acyclic cucurbit[n]uril-type molecular containers: influence of glycoluril oligomer length on their function as solubilizing agents

We present the synthesis of a series of six new glycoluril derived molecular clips and acyclic CB[n]-type molecular containers (1–3) that all feature SO3(−) solubilizing groups but differ in the number of glycoluril rings between the two terminal dialkoxyaromatic sidewalls. We report the X-ray crystal structure of 3b which shows that its dialkoxynaphthalene sidewalls actively define a hydrophobic cavity with high potential to engage in π–π interactions with insoluble aromatic guests. Compounds 1–3 possess very good solubility characteristics (≥38 mM) and undergo only very weak self-association (Ks < 92 M(−1)) in water. The weak self-association is attributed to unfavorable SO3(−)···SO3(−) electrostatic interactions in the putative dimers 12–42. Accordingly, we created phase solubility diagrams to study their ability to act as solubilizing agents for four water insoluble drugs (PBS-1086, camptothecin, β-estradiol, and ziprasidone). We find that the containers 3a and 3b which feature three glycoluril rings between the terminal dialkoxy-o-xylylene and dialkoxynaphthalene sidewalls are less efficient solubilizing agents than 4a and 4b because of their smaller hydrophobic cavities. Containers 1 and 2 behave as molecular clip type receptors and therefore possess the ability to bind to and thereby solubilize aromatic drugs like camptothecin, ziprasidone, and PBS-1086.

Synthesis and Recognition Properties of Cucurbit[8]uril Derivatives

A building block approach to the synthesis of Me4CB[8] and Cy2CB[8] by condensation of glycoluril hexamer 1 with bis(cyclic ethers) 2 is reported. X-ray crystallography demonstrates that the equatorial substitution results in an ellipsoidal cavity. Me4CB[8] and Cy2CB[8] display enhanced aqueous solubility and retain the ability to bind to guests (3-9) typical of unsubstituted CB[8]. The higher inherent solubility of Me4CB[8] allowed it to be used as a solubilizing excipient for insoluble drugs.

Direct syntheses of cucurbit[7]uril-anchored polyacrylic acid microspheres and adsorption of basic dyes by the derivative

A series of cucurbit[7]uril-anchored polyacrylic acids were synthesized using (NH₄)₂S₂O₈ as both an initiator and oxidant. The polymers were further esterified with 2-naphthol to yield derivatives, which could be used as a stationary phase for the absorption of basic dyes.

Supramolecular assembly of a methyl-substituted cucurbit[6]uril and its potential applications in selective sorption

Assembly of a methyl-substituted cucurbit[6]uril derived from 3α-methyl-glycoluril (HMeQ[6]) has been studied. We have demonstrated potential applications of this system based on the selective sorption of volatile alcohols in the polar channels, especially methanol.