CdS-Based Catalysts Derived from TMeQ[6]/[CdCl]-Based Frameworks for Oxidation Benzylamine.

The anion-induced outer surface interaction of Q[]s is an important driving force in the construction of Q[]-based supramolecular frameworks. In this work, a symmetric tetramethyl-substituted cucurbit[6]uril (TMeQ[6]) is selected as the basic structural block. Using the anion-induced outer surface interaction of Q[]s derived from [CdCl] anions formed by Cd cations in a HCl medium, four different TMeQ[6]-[CdCl]-based supramolecular frameworks are constructed.

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.

Outer surface interactions to drive cucurbit[8]uril-based supramolecular frameworks: possible application in gold recovery.

Q[8]-based honeycomb-like frameworks can be obtained in [AuCl4]--free aqueous HNO3 solution and aqueous HCl and HNO3 solutions that contain [AuCl4]-. The outer surface interaction of Q[8] with planar inorganic anions [AuCl4]- and NO3- is the main driving force. These frameworks exhibit a high selectivity for imprisoning [AuCl4]- that could establish a process for gold recovery.

Hexamethylcucurbit[3,3]uril-Based Porous Supramolecular Assemblies and Their Adsorption Properties.

In the present work, we selected hexamethylcucurbit[3,3]uril (MeQ[3,3]) as a building block and obtained two MeQ[3,3]-based porous supramolecular assemblies from neutral water () and aqueous HCl solutions (), respectively. Both MeQ[3,3]-based assemblies are constructed of MeQ[3,3] molecules through the typical outer surface interaction of cucurbit[]urils, as well as hydrogen bonding between latticed water molecules and portal carbonyl oxygens of MeQ[3,3]. The assemblies present different porous structure features and exhibit different adsorption properties for eight common volatile organic compounds.

Coordination supramolecular assemblies of a monohydroxycucurbit[7]uril and their potential applications in gas sorption.

Coordination supramolecular assemblies of monohydroxycucurbit[7]uril ((HO)Q[7]) with alkaline earth metal ions (AE) have been formed in aqueous HCl solution in the presence of tetrachloride cadmium anions ([CdCl]) as a structure directing agent. The driving force for the assembly could be attributed to the interaction of the positive electro-potential outer-surface of (HO)Q[7] molecules with [CdCl] anions and ionic dipole interaction of the hydroxyl of (HO)Q[7] molecules with [CdCl] anions. Moreover, the porous structure of the (HO)Q[7]/AE-based coordination supramolecular assemblies could result in potential applications in the selective sorption of polar volatile organic molecules, which may be useful in molecular sieves, sensors, absorption and separation.

Mono- and Dihydroxylated Symmetrical Octamethylcucurbiturils and Allylated Derivatives.

Mono- and dihydroxylated symmetrical octamethylcucurbit[6]urils {(OH)OMeQ[6] and (OH)OMeQ[6]} were prepared using a photochemical method to introduce limited alcohol group(s) directly to the parent symmetrical octamethylcucurbit[6]uril (OMeQ[6]), and the resulting compounds were verified by H NMR, Xevo Q-TOF MS, and X-ray crystallography. Further chemical modification of mono- and dihydroxylated OMeQ[6] was also performed.

Twisted Cucurbit[n]urils.

Two new twisted cucurbiturils, cucurbit[13]uril (tQ[13]) and cucurbit[15]uril (tQ[15]), have been synthesized and separated, and their structures have been confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry together with the X-ray structures of two new complexes, {Dy(H2O)4Cd(H2O)4tQ[13]}·2.5[CdCl4]·65H2O and {Cd0.5(H2O)2tQ[15]}·[CdCl4]·47H2O.

[The Interaction of Cucurbit[8]uril with Thionine and Carbendazim with Spectroscopic Method].

In this paper, the interaction of cucurbit [8]uril(Q[8]) with thionine (TH) and carbendazim (CBZ) were investigated with fluorescence and UV-Vis spectroscopy. The experimental results showed that the inclusion complex between Q[8] and TH informed was at molar ratios of 1∶2 in 0.01 mol·L-1 hydrochloric acid solution.

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.

[Interaction of Cucurbit[8]uril with β-Indoleacetic Acid and Methylviologen].

The interaction between Q[8] with β-indoleacetic acid and the methylviologen was studied in aqueous solution with electronic absorption spectroscopy (UV-Vis), fluorescence spectroscopy, 1H NMR spectroscopy and isothermal titration calorimetry (ITC) in details. The authors explored the mode of action, action site and thermodynamic properties of the host-guest system. The electronic absorption and fluorescence spectroscopy data showed that the Q[8]/IAA system and Q[8]/MV²⁺ system informed 1:1 inclusion complexes in aqueous solution.

Encapsulation of alkyldiammonium ions within two different cavities of twisted cucurbit[14]uril.

Binding interactions between twisted cucurbit[14]uril (tQ[14]) and a series of alkyldiammonium ions both in aqueous solution and DMSO media were investigated by NMR spectroscopy and ITC. Experimental data indicate that tQ[14] possesses two kinds of cavities with different space environments, which can encapsulate two or even three guest molecules with suitable shape and size.

A Hemimethyl-Substituted Cucurbit[7]uril Derived from 3α-Methyl-glycoluril.

A novel hemimethyl-substituted cucurbit[7]uril (HMeQ[7]) derived from 3α-methyl-glycoluril has been prepared. HMeQ[7] is readily soluble in both water and dimethyl sulfoxide (DMSO) and displays not only host-guest interaction properties similar to those of the normal cucurbit[7]uril but also unusual properties in DMSO.

Interaction of Ln with Methyl-Substituted Cucurbit[n]urils (n=5,6) Derived from 3α-Methyl Glycoluril.

The interactions between a series of lanthanide cations (Ln ) and methyl-substituted cucurbiturils (SPMeQ[5] and SHMeQ[6]) derived from a 3α-methyl glycoluril have been investigated. Single-crystal X-ray diffraction analysis revealed that both SPMeQ[5] and SHMeQ[6] selectively interact with certain lanthanide ions. SPMeQ[5] forms coordination capsules in the presence of [CdCl ] .

A novel shell-like supramolecular assembly of 4,4'-bipyridyl derivatives and a twisted cucurbit[14]uril molecule.

This work showed that the 4,4'-bipyridyl group and alkyl chains of 4,4'-bipyridyl derivatives are completely located in the shell-like cavity of the twisted cucurbit[14]uril molecule and formed novel shell-like 1 : 1 inclusion complexes. As it is enthalpy-driven the complexation benefits from ion-dipole interactions.

Encapsulation of haloalkane 1-(3-chlorophenyl)-4-(3-chloropropyl)-piperazinium in symmetrical α,α',δ,δ'-tetramethyl-cucurbit[6]uril.

Complexation of haloalkane 1-(3-chlorophenyl)-4-(3-chloropropyl)-piperazinium (PZ(+)) dihydrochloride with symmetrical α,α',δ,δ'-tetramethyl-cucurbit[6]uril (TMeQ[6]) has been investigated using NMR spectroscopy, MALDI-TOF mass spectrometry, isothermal titration calorimetry (ITC), and X-ray crystallography. Our data indicate that the chloropropyl group of PZ(+) resides within the cavity of TMeQ[6] in both aqueous solution and the solid state, generating a highly stable inclusion complex PZ(+)@TMeQ[6]. In aqueous solution, the formation of the inclusion complex PZ(+)@TMeQ[6] benefits from the ion-dipole interactions between the guest PZ(+) and the host TMeQ[6].

Coordination of alkaline earth metal ions in the inverted cucurbit[7]uril supramolecular assemblies formed in the presence of [ZnCl4]2- and [CdCl4]2-.

A convenient method to isolate inverted cucurbit[7]uril (iQ[7]) from a mixture of water-soluble Q[n]s was established by eluting the soluble mixture of Q[n]s on a Dowex (H(+) form) column so that iQ[7] could be selected as a ligand for coordination and supramolecular assembly with alkaline earth cations (AE(2+)) in aqueous HCl solutions in the presence of [ZnCl(4)](2-) and [CdCl(4)](2-) anions as structure-directing agents. Single-crystal X-ray diffraction analysis revealed that both iQ[7]-AE(2+) -[ZnCl(4)](2-) -HCl and iQ[7]-AE(2+) -[CdCl(4)](2-) -HCl interaction systems yielded supramolecular assemblies, in which the [ZnCl(4)](2-) and [CdCl(4)](2-) anions presented a honeycomb effect, and this resulted in the formation of linear iQ[7]/AE(2+) coordination polymers through outer-surface interactions of Q[n]s.

Extended and contorted conformations of alkanediammonium ions in symmetrical α,α',δ,δ'-tetramethylcucurbit[6]uril cavity.

Binding interactions between symmetrical α,α',δ,δ'-tetramethylcucurbit[6]uril (TMeQ[6]) and a series of alkyldiammonium ions in aqueous solution and in the solid state were investigated by (1)H NMR spectroscopy, MALDI-TOF mass spectrometry, X-ray crystallography, and isothermal titration calorimetry (ITC). Their (1)H NMR spectra reveal that the actual binding behaviors vary depending upon the alkyl chain length. Their single-crystal X-ray diffraction analyses indicate the guest 1,2-ethanediammonium is located outside of the TMeQ[6] portal, while the other four alkyldiammonium guests can be accommodated in the TMeQ[6] cavity, forming 1:1 inclusion complexes.

Self-assemblies based on the "outer-surface interactions" of cucurbit[n]urils: new opportunities for supramolecular architectures and materials.

Supramolecular architectures and materials have attracted immense attention during the last decades because they not only open the possibility of obtaining a large variety of aesthetically interesting structures but also have applications in gas storage, sensors, separation, catalysis, and so on. On the other hand, cucurbit[n]urils (Q[n]s), a relatively new class of macrocyclic hosts with a rigid hydrophobic cavity and two identical carbonyl fringed portals, have attracted much attention in supramolecular chemistry. Because of the strong charge-dipole and hydrogen bonding interactions, as well as hydrophobic and hydrophilic effect derived from the negative portals and rigid cavities of Q[n]s, nearly all research in Q[n]s has been focused on utilizing the portals and cavities to construct supramolecular assemblies similar to other macrocyclic receptors such as cyclodextrin and calixarenes.

Tetrachloridometallate dianion-induced cucurbit[8]uril supramolecular assemblies with large channels and their potential applications for extraction coating on solid-phase microextraction fibers.

Q[8]-based porous materials were synthesized in the presence of [Md-blockCl4](2-) anions as structure inducers. The driving forces of the structure-directing effect of the [Md-blockCl4](2-) anions may be due to the ion-dipole interaction and hydrogen bonding between the [Md-blockCl4](2-) anions and ≡CH or ═CH2 groups on the backs of Q[8] molecules. Moreover, the tests of potential applications show that these porous materials can not only capture organic molecules through the cavity of Q[8] moieties but also adsorb larger organic molecules with different selectivities.

[CdCl4]2- anion-induced coordination of alkaline earth metal ions to cucurbit[7]uril, corresponding supramolecular self-assemblies and potential application.

In the present work, we describe three cucurbit[7]uril-based coordination supermolecular self-assemblies in the presence of [M(trans)Cl4](2-). It can affect the construction of Q[7]/metal ions-based coordination polymers, at the same time it can result in the formation of Q[7]-based supramolecular assemblies when introducing the [M(trans)Cl4](2-) into the Q[7]/metal ions system.

Cucurbit[n]uril-based coordination chemistry: from simple coordination complexes to novel poly-dimensional coordination polymers.

Cucurbit[n]urils are a family of molecular container hosts bearing a rigid hydrophobic cavity and two identical carbonyl fringed portals. They have attracted much attention in supramolecular chemistry because of their superior molecular recognition properties in aqueous media. This review highlights the recent advances and challenges in the field of cucurbit[n]uril-based coordination chemistry.

Construction of cucurbit[7]uril based tubular nanochannels incorporating associated [CdCl4]2- and lanthanide ions.

There is intensive interest in the design of tubular channels because of their novel structures and various applications in a variety of research fields. Herein, we present a series of coordination-driven Q[7]-derived organic nanochannels using an anion-induced strategy under different acid concentrations. An advantage of this approach is that the tubular channels not only retain the original character of the parent macrocyclic receptors but also provide deep hydrophobic cavities possessing guest binding sites.

Novel supramolecular assemblies based on coordination of samarium cation to cucurbit[5]uril.

In the present study, we introduce the coordination of samarium-Q[5] systems in the absence and presence of the third species, and the corresponding supramolecular assemblies are dependent upon the addition of the third species. In the absence of the third species, a samarium cation (nitrate salt) coordinates to a Q[5] molecule and forms a molecular bowl; in the presence of an organic molecule (hydroquinone), a one-dimensional polymer of ···Sm-Q[5]-Sm-Q[5]-Sm··· is formed through direct coordination of Sm cation to the portal carbonyl oxygens. In the presence of nickel cations (chloride salt), an infinite 1D supramolecular chain is constructed of samarium/cucurbit[5]uril molecular bowl through ion-dipole interaction and hydrogen binding; in addition, the stacking of the supramolecular chains forms a novel hexagonal open framework.

Difference of coordination between alkali- and alkaline-earth-metal ions to a symmetrical α,α',δ,δ'-tetramethylcucurbit[6]uril.

To explore differences in coordination between alkali- and alkaline-earth-metal ions and cucurbit[n]urils, a water-soluble α,α',δ,δ'-tetramethylcucurbit[6]uril (TMeQ[6]) was used to synthesize a series of complexes and their supramolecular assemblies, based on the coordination of TMeQ[6] with alkali- and alkaline-earth-metal ions. The complexes and corresponding supramolecular assemblies were structurally characterized by single-crystal X-ray diffraction. Unlike cucurbituril (Q[6]), which formed the metal-Q[6] polymers based on the direct coordination of carbonyl oxygen atoms to the alkali-metal ions, TMeQ[6] formed metal-TMeQ[6] polymers based on the direct coordination of carbonyl oxygen atoms with the alkaline-earth-metal ions rather than the alkali-metal ions.