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A supramolecular chiral electrode was constructed by layer-by-layer assembly of gold nanoparticles (AuNPs) and an S-chiral multifarene [3,2,1] (S-CMF) on the surface of a glassy carbon electrode, which was applied for the electroreduction of acetophenone. The host-guest encapsulation of the substrate within the chiral cavity was confirmed by 1H NMR, fluorescence titration, and molecular simulation. The composite on the electrode surface was characterized by electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM). Optimization of the electrolysis process was performed to give a high yield of 70.9% and high enantioselectivity of 63.9% ee, which exhibited superior reactivity to the previously reported materials. The repeatability of the experiment was tested via five separate experiments and indicated consistent stability, recyclability, and reusability of the novel chiral electrode. The proposed mechanism involved supramolecular encapsulation, two single-electron transfer steps, and proton addition. The chiral electroorganic reduction was extended to more substrates to provide successful yields and enantioselectivity.

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.

Electrochemical sensing is a promising analytic method with its advantages, such as low cost, fast response, simple operation, high accuracy, low detection limit and so on. With the rapid development of electroanalysis, various modified electrodes were synthesized for constructing different kinds of electrochemical sensors on purpose. Macrocyclic compounds with their superior supramolecular recognition properties have aroused the research interest, as they can be used as modifiers for enhancing the sensitivity and selectivity of electrodes. All five classic macrocyclic compounds, which are crown ethers, cyclodextrins, calixarenes, cucurbiturils, and pillararenes, have been employed as receptors for electrochemical sensors, and these macrocycles have led to a wilder detection range, a lower detection limit, and superior ability of anti-interferences against coexisting ions or molecules. The macrocycles modified electrodes have shown greater sensitivity and selectivity in detection. Therefore, this review focuses on the results of the studies published in recent 8 years on macrocycles improved electrochemical sensing. In this review, the recent development of functionalization of macrocyclic compounds including crown ethers, cyclodextrins, calixarenes, cucurbiturils, pillararenes, on electrochemical sensors has been summarized.

Fluorescent chemosensors based on a new macrocyclic compound, multifarene[2,2], with modification by triazole-linked pyrene or anthracene were synthesized. These macrocyclic sensors exhibited high affinity and selectivity toward Ag+ over other metal ions, with ratiometric or enhanced response of their fluorescence emissions depending upon the substituent species for coordination to Ag+, and an unexpected response to a concentration threshold of the metal cations was discovered. The experimental evidences of fluorescence spectra, 1H NMR titration, IR spectra, and high-resolution mass spectra suggested the coordination behaviors of the sensors with Ag+, that is, the 1:1 complexes were formed with moderate association constants of about 105 L·mol−1, and the sulfur atoms on macrocyclic ligand should affinite to the metal cations. Energy-minimized structures and frontier orbitals were estimated by quantum chemical calculations with a view to rationalizing the fluorescence response of the multifarene[2,2] sensors upon binding to Ag+.

Carboxymethyl-substituted and ester-substituted benzo[3]urils have been successfully synthesized and investigated with regard to the supramolecular recognition of inorganic ions by means of fluorescence spectroscopy, 1H NMR spectrometry, and quantum chemical calculations. The results indicated that benzo[3]uril 4 bearing six carboxyl groups binds to Cu2+, Fe3+, F−, and CH3COO− with strong affinities. Moreover, this macrocyclic host could be used to recognize ion pairs comprising Cu2+ and CH3COO−, Cu2+ and F−, Fe3+ and CH3COO−, and Fe3+ and F− through its fluorescence response. In contrast, benzo[3]uril 3, bearing ester groups, showed only host–guest interactions with Cu2+ and Fe3+. The absence of binding of the macrocycle 3 to anions highlights the important role of the carboxyl groups on benzo[3]uril 4, which provide active protons to form hydrogen bonds between the host and anion guests.

With a facile preparation for graphitic carbon nitride quantum dots (g-C3N4 QDs), an ultrasensitive photoelectrochemical (PEC) sensor was developed with the supramolecular affinity of chiral multifarene[3,2,1] (CMF) to a hormone drug, thyroxine (T4), for efficient identification of thyroxine enantiomers. In the principle that g-C3N4 QDs was employed to achieve the photocurrent response and the macrocyclic compound served as the supramolecular enantiorecognition for thyroxine, the photoelectrochemical electrode was constructed by layer-by-layer assembly of g-C3N4 QDs and CMF on the surface of ITO (ITO-g-C3N4-CMF QDs). The proposed PEC sensor produced the limits of detection low to 67 pM towards L-T4 and 85 pM towards D-T4 in a concentration range from 0.1 nM to 10 nM, which was superior to the values in pioneering reports with colorimetric or electrochemical methods. With good stability, reproducibility, repeatability anti-interference ability, and acceptable recoveries, the proposed PEC sensor was employed for quantitative determination of L/D-T4 in water, human serum and commercial tablet.

A new inverted cucurbituril, namely inverted hexamethylcucurbit[3,3]uril (iMe6Q[3,3]), has been isolated and characterized. It incorporates a single inverted un-substituted glycoluril unit oriented towards the interior of the cavity, shows good solubility in water and organic solvents (DMSO), and exhibits different selecties for guests to those of iQ[6] and other known Q[6]s.

The supramolecular interaction between hemicucurbit[6]uril (HemiQ[6]) and ferrocene is investigated using 1 H and 13 C NMR spectroscopy, cyclic voltammetry (CV), isothermal titration calorimetry (ITC) and quantum chemistry. By means of the 1 H NMR and 13 C NMR spectra, the host-guest interaction is confirmed by the slight shift in the resonance peaks of ferrocene. Cyclic voltammetry shows the diffusion current of ferrocene was enhanced with a slight improvement in the voltammetric behavior in the presence of HemiQ[6]. Isothermal titration calorimetry provides thermodynamic data for the host-guest interaction and an association constant of K a = 4.9 × 10 4 L mol −1 in a 1:1 ratio has been obtained. Quantum chemistry suggests the encapsulation complex was stabilized by the formation of hydrogen bonding between the aromatic protons on the ferrocene guest molecule and the carbonyl groups on hemicucurbit[6]uril, and the electron transfer of the interaction complex is more easy than in free ferrocene.

The host–guest interaction between tetramethylcucurbit[6]uril (TMeQ[6]) and 2-(4-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline hydrochloride salt (guest 1) has been investigated. 1H NMR results have confirmed the formation of an encapsulated complex, and fluorescence titration implies an interaction ratio of 1:1 with a moderate association constant of Ka = 4.0 × 106 L mol−1. The triggered fluorescence emission of guest 1 by TMeQ[6] has been developed to achieve a supramolecular probe capable of recognizing La3+ and Ce3+ through a dramatic decrease in fluorescence intensity, whereas there is minimal difference upon the introduction of Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Er3+, or Tm3+. Combined evidence from 1H NMR, IR, and fluorescence titration supports coordination of the inclusion complex to La3+ and Ce3+, with association constants of 1.1 × 104 L mol−1 and 1.0 × 104 L mol−1, respectively. The linear decrease in fluorescence intensity in response to different concentrations of La3+ or Ce3+ gives a low limit of detection (LOD) of 1.1 × 10−8 mol L−1.

Members of a new class of macrocyclic compounds, benzo[6]urils bearing hydroxymethyl or methyl groups, have been synthesized under mild conditions in high yields. These macrocycles have been employed as hosts to encapsulate bipyridine guests. Fluorescence spectrometric titrations confirmed the formation of interaction complexes in a 1 : 1 ratio and curve-fitting of the decreases in fluorescence intensity of the benzo[6]urils in the presence of the guests provided moderate association constants of about 1.5 × 103–1.3 × 106 L mol−1. The stabilities of the supramolecular complexes proved to be dependent on both the structures of the guests and the substituents present on the host. The host–guest interactions have also been probed by means of 1H NMR spectrometry, whereby small shifts in the resonances of the benzo[6]uril upon the addition of the guest were observed. The results of DFT calculations suggested that the encapsulation capabilities of benzo[6]urils should rest with the electronic structures of the guests.

A new macrocyclic compound, benzo[3]uril 1, was synthesized in a facile manner, and displayed a unique fluorescence response upon recognition and binding of Cu2+, Fe3+, F−, and acetate.[1]H NMR (Nuclear Magnetic Resonance) spectra confirmed that binding occurs through hydrogen bonds between hydroxyl groups on the benzo[3]uril 1 and F− or acetate anions. The successful synthesis of benzo[3]uril 2 demonstrates that modification of this macrocycle is relative easy, and the absence of an interaction with anions further supports the importance of hydrogen binding between benzo[3]uril 1 to F− and acetate. Infra-red (IR) spectroscopy suggest the carboxyl groups of benzo[3]uril coordinate metal cations Cu2+ and Fe3+.

The host–guest interactions of hemicucurbit[6 and 12]urils with the Schiff base guest 1 has been investigated. 1H NMR spectra suggest hemicucurbit[6 and 12]urils bind to guest 1 with the formation of hydrogen bondings between the phenol hydroxyl group and carbonyl groups in the host. The formation of interaction complexes are also supported by fluorescence emission spectroscopy. The moderate association constants of the interaction complexes in a ratio of 1:1 are obtained to be (3.2 ± 0.6) × 105 and (5.5 ± 0.8) × 105 L mol−1, respectively, via non-linear curve fitting, which indicate that the formation of hydrogen bondings are important in the host–guest interactions.

The host–guest interactions between hemicucurbit[6 and 12]urils and o-, m-, and p-aminophenols have been investigated by means of 1H NMR spectrometry, fluorescence emission spectroscopy, and isothermal titration calorimetry. The 1H NMR spectra suggest that the interaction could involve hydrogen bonding between the hydroxyl groups of the guests and the carbonyl groups of the hemicucurbiturils. The fluorescence emissions of the guests are enhanced upon addition of increasing amounts of hemicucurbiturils, with a slight blue-shift of the emission peaks. Moreover, the linearity of emission intensity responses of the guests to the HemiQs concentration shows different slopes depending on the structure of the hemicucurbituril. Thermodynamic data have been obtained by isothermal titration calorimetry, and the results indicate 1:1 host–guest interactions between the hemicucurbiturils and aminophenols. All of the interaction systems have similar stabilities and approximately equal association constants, and the negative enthalpy change upon the addition of the hemicucurbiturils is the driving force of the host–guest interaction. Formation of interaction complexes of aminophenols with hemicucurbit[6 and 12] in organic solvent have been investigated.

The host-guest interaction of cucurbit[8]uril (Q[8]) with a synthesized guest molecule, consisting of naphthalene and viologen moieties bridged by a carbon oxygen chain, was investigated by (1)H NMR and UV-Vis spectroscopy. The results indicated the formation of an inclusion complex in a ratio of 1 : 1 with a moderate association constant of Ka = (1.1 ± 0.2) × 10(6) L mol(-1). The formation of this special complex is driven by the markedly enhanced charge-transfer interaction between the electron-rich and electron-deficient guest molecule inside the hydrophobic cavity of Q[8], while the carbon oxygen chain stays outside of Q[8] to form a supramolecular crown ether. Screening of the metal cation substrate suggested that the inclusion complex recognizes Ag(+) ions with high selectivity, as shown by UV-Vis spectroscopy.

Compared to isolated, simple Ln3+/Q[6] complexes in the absence of polychloridometallate ions, linear coordination polymers have been assembled from lanthanide cations (Ln3+) and cucurbituril (Q[6]) in the presence of polychloridometallate ions as inorganic structure inducers in HCl solution. X-ray diffraction analysis has revealed that not only [CuCl4]2− anions but also [FeCl2(H2O)4]+ cations can induce the coordination of Ln3+ cations to Q[6] so as to form Ln3+/Q[6]-based tubular coordination polymers. The driving forces are considered to be interaction of the electron-deficient carbon sites of the carbonyl dipoles of Q[n] molecules with the chloride ends of the Md-block−Cl bonds in the [Md-blockClx]n− anions or [Md-blockClx]m+ cations, as well as unusual hydrogen bonding between the methine and methylene groups on the back of adjacent Q[n] molecules and the chlorine atoms of the [Md-blockClx]n− ions. We have classified such interactions as ‘back-interaction of Q[n]s’.

Fluorescence and electrochemical response of multifarene[3,3](S) to serotonin hydrochloride and its quantitative measurement by hybridization on the surface of reduced graphene oxide were investigated. The fluorescence titration suggested the formation of host–guest complex in a radio of 1:1, and the moderate association constants of (1.7 ± 0.3) × 104 M (in DMSO) and (2.7 ± 0.2) × 104 M (in water) were obtained by non-linear curve fitting, which implied the supramolecular interaction could be irrelevant to the species of solvents. Furthermore, the hybridization of multifarene[3,3](S) with reduced graphene oxide improved the response to serotonin hydrochloride in both fluorescence and voltammetry, which was employed to realize the quantitative analysis for the drug, and a low limit of detection of 3.9 × 10−7 M was found for determination in the real simple of human serum.

The composites of benzo[6]uril-hybridized graphene oxide were realized with the full characterization of atomic force microscopy (AFM), Infrared spectroscopy (IR), and Raman spectroscopy, which exhibited dramatical improvement of the fluorescence response to the supramolecular interactions of umbelliferones with the macrocyclic compounds to produce the ternary supramolecular hybrid materials, and the host-guest interactions were evidenced with 1H NMR, fluorescence titrations, and molecular simulations to confirm the encapsulation of the umbelliferone guests within the cavities of the macrocyclic hosts. The supramolecular materials were applied for quantitative determination for diquat to give the limits of detection of 3.4 × 10−7 mol L−1 and 5.0 × 10−7 mol L−1, respectively, with high selectivity in coexistence of other bipyridyl interferences including 2,2′-bipyridine, 4,4′-bipyridine, and methyl viologen in aqueous solutions.

The chem-sensors, based on the triazole-CH2-anthracene-functionalized multifarene[2,2] were successfully synthesized, which could efficiently and rapidly detect 2,4,6-trinitrophenol (TNP). The high specificities of the proposed macrocyclic sensors were achieved by selective response for TNP in the existence of other competing phenolic compounds, and the limits of detection in ∼10−8 mol/L range were produced to confirm the high sensitivities of the chem-sensors, which could be attributed to the mechanism of electron and resonance energy transfer processes in the complexes with the supramolecular interactions. 1H NMR titration analysis revealed the actual binding position should be the triazole rings of sensors with the hydroxyl group on TNP to offer a hydrogen bonding. The extraordinary sensing properties endued the compounds as sensitive fluorometric chem-sensors for the potential application of TNP detection.

Electrochemical response of a carbon paste electrodes modified by cucurbit[8]uril (Q[8]) has been described. The electrochemical characterization of Q[8]-modified electrode (Q[8]MCPE) by using cyclic voltammetry exhibits the recognition to phenols. For two series of substrates, o-, m-, p-hydroxybenzyl alcohol and o-, m-, p-methoxyphenol, the special response depends on the structures of substrates, the modification with macrocyclic compound Q[8] always favors m-substituted phenols. The electrochemical response of a cucurbit[8]uril-modified carbon paste electrodes to phenols has been described.

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. Interestingly, a recent study revealed that other weak noncovalent interactions such as hydrogen bonding and π···π stacking, as well as C-H···π and ion-dipole interactions, could also be defined as "outer-surface interactions", which are derived from the electrostatically positive outer surface of Q[n]s. These interactions could be the driving forces in the formation of various novel Q[n]-based supramolecular architectures and functional materials. In this Account, we provide a comprehensive overview of supramolecular self-assemblies based on the outer-surface interactions of Q[n]s. These outer-surface interactions include those between Q[n]s, Q[n]s and aromatic molecules, Q[n]s and calixarenes, Q[n]s and inorganic complex ions, and Q[n]s and polyoxometalates. Pioneering work has shown that such weak noncovalent interactions play very important roles in the formation of various Q[n]-based functional materials and supramolecular architectures. For example, hydrogen bonds in outer-surface interactions between Q[n] molecules not only function as the sole driving force in the formation of one-dimensional Q[n] porous channels but also assist the bonding forces of the channels in capturing and accommodating acetylene molecules and carbon dioxide in the channel cavities. Moreover, upon introduction of a third species such as an aromatic molecule or inorganic anion into the Q[n]/metal system, "outer-surface interactions" could lead to Q[n]/metal-based self-assemblies from simple finite supramolecular coordination complexes to infinite polydimensional supramolecular architectures and other structures. Overall, this Account focuses on the novel self-assembly driving force derived from Q[n]s including (i) concepts of the outer-surface interactions of Q[n]s, (ii) providing plausible explanations of the mechanisms of the outer-surface interactions of Q[n]s, and (iii) introduction of an overview of the developments and practical applications of outer-surface interactions of Q[n]s in supramolecular chemistry. It is hoped that this study based on the outer-surface interactions of Q[n]s can enrich the field of molecular engineering of functional supramolecular systems and provide new opportunities for the construction of functional materials and architectures.

In the present work, we describe four previously unreported cucurbituril-based coordination supramolecular self-assemblies, formed in the presence of alkali metal and cadmium ions. Unexpectedly, in the presence of potassium or rubidium and cadmium cations, cucurbituril prefers to coordinate with cadmium to form three dimensional frameworks. The alkali metal ions seem to play a role of structure inducer in HCl medium and are not present in the final structures. In neutral aqueous solution, cadmium cations also show stronger coordination to cucurbituril and form one-dimensional supramolecular chains through static electronic interactions. When the alkali metal ion is sodium in HCl solution, sodium ions show stronger coordination to cucurbituril and form one-dimensional coordination polymers. [CdCl4]2– anions link the linear polymers through static electronic interactions between coordinated chloride anions and sodium cations, which results in the formation of two-dimensional networks.

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.

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.

A chemical investigation reveals that the resistance to acylation of an anti-tuberculosis drug, isoniazid is a consequent result of the inclusion or exclusion of cucurbit[n]urils (n = 6 or 7). The (1)H NMR spectra analysis shows that the different interaction models of the isoniazid with the two cucurbiturils are dependent on the cavity size of the hosts. Quantum chemistry calculations with density functional theory method indicate that the interaction of the isoniazid with both cucurbiturils is through thermodynamic stabilization in both the gas phase and aqueous solution through hydrogen bonding on the portal carbonyls of the cucurbiturils. Electronic absorption titration spectra suggest the hosts and guest interact in a ratio of 1 : 1 with moderate binding constants. Acylation kinetics of isoniazid with various acylating agents in the presence of the cucurbiturils revealed that resistance is only dependent on the host-isoniazid ratio, and independent on the size of the cucurbiturils and the species of acylating agents.

The recent work has revealed that Q[n]-based coordination chemistry is gradually changing from simple coordination to novel polydimensional coordination polymers of metal ions to Q[n]s. In particular, our recent study revealed that the coordination of Q[n]s with metal ions in the presence of a third species (often an anionic species or an organic molecule), that is, a structure inducer, can result in the formation of various cucurbit[n]uril-based polydimensional supramolecular coordination architectures and polymers. Weak noncovalent interactions derived from the “outer-surface interactions” of Q[n]s, such as hydrogen bonding, π···π stacking, and C–H···π and ion–dipole interactions, have important roles in those systems. Detailed investigations have indicated that such noncovalent interactions can be the main driving forces in the formation of Q[n]-based supramolecular assemblies and functional materials. For example, the pore sizes and hydrophobic cavities of these compounds that lead to unprecedented properties, and potential applications in gas absorption, polycyclic aromatic hydrocarbons (PAHs) separation, and so on.

The host–guest interaction of cucurbit[7]uril (Q[7]) with the new fluorescent sensor guest molecule (BIBPAH+), formed by alkylation of the secondary amine site in N,N-bis(2-pyridylmethyl)amine with 2-(bromomethyl)benzimidazole, was investigated by fluorescence and 1H NMR spectroscopy. The results indicate the formation of an inclusion complex in a 1:1 ratio with an association constant of Ka = (2.9 ± 0.7) × 105 L ∙ mol−1. There is minimal difference in the fluorescence intensities upon the introduction of each of Mn2+, Ni2+, Co2+, Cr3+, Ho3+ and Lu3+. However, the emission was slightly quenched on the addition of Cu2+ or Fe3+ whether Q[7] is present or not. Further investigation showed that encapsulation of BIBPAH+ in Q[7] improves Cd2+ and Zn2+ recognition by enhancing the fluorescence intensity, leading to an improvement in the limits of detection. In contrast, comparative parallel experiments in which Cu2+, Mn2+, Ni2+, Co2+, Fe3+, Cr3+, Ho3+ or Lu3+ were substituted for Zn2+ or Cd2+ resulted in minimal changes in the fluorescence that occurs for the corresponding metal-free system. The natures of the encapsulated Zn2+ and Cd2+ complexes have been investigated using fluorescence and 1H NMR spectroscopy as well as by quantum chemistry. The selectivity of a fluorescent sensor for Cd2+ and Zn2+ was improved by its encapsulation within the cavity of cucurbit[7]uril.

Because of their superior molecular recognition properties in aqueous media, cucurbit[n]urils (Q[n]s or CB[n]s), which bear a rigid hydrophobic cavity and two identical carbonyl fringed portals, have attracted much attention in supramolecular chemistry. Till date, the homologs of unfunctionalized cucurbit[n]urils include 5, 6, 7, 8, 10, and 14. Meanwhile, a number of substituted cucurbit[n]urils (SQ[n]s) and their derivates were reported during the last decade. Therefore, in this chapter the development of cucurbit[n]urils and their derivates is first briefly reviewed. Importantly, the general properties of out surface-interactions of Q[n]s proposed by us recently and their roles in Q[n]-based coordination chemistry or Q[n]-based host-guest/coordination chemistry are also highlighted in this chapter.

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. It not only presents progress in the knowledge of such macrocyclic compounds, which range from simple to complicated architectures, but also presents new routes of synthesis and their advantages in hybrid porous solids. The concept of structure "inducer" for their structural design to achieve predictable structures and controlled pores is described. The large pore sizes and hydrophobic cavities of these compounds that lead to unprecedented properties and potential applications are also discussed.

The chemo-selective oxidation of bifunctional substrates via a supramolecular strategy has been achieved. IBX (o-iodoxybenzoic acid) oxidations of hydroxybenzyl alcohols produce the corresponding aldehyde and o-quinones, while the presence of HemiQ[6] can restrain the IBX oxidation of phenolic hydroxyl groups to afford the aldehyde product. The conversion and reaction rate are greatly affected by the structures of substrates, and the stereo effect and electronic effect play very important roles in the selective oxidation system. Various spectroscopies, including 1H NMR (proton nuclear magnetic resonance), IR (infrared), and UV-vis (ultra violet-visible) have been employed to confirm the host–guest interaction of HemiQ[6] with hydroxybenzyl alcohols.