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As a derivable modified hemicucurbituril, aniline-containing hemicucurbituril was synthesized in our previous report. Functionalization on the amino group of this aniline-containing hemicucurbituril was investigated, and a novel sulfonamide modified hemicucurbituril was obtained by sulfonation on the amino group with tosyl chloride, providing a novel hydrogen donor macrocycle. This macrocycle showed no interaction with aniline and benzoic acid and aminobenzoic acid by the 1H NMR study, but showed obvious interaction with these corresponding benzoate salts which was a class of preservative. These host-guest interaction properties made this system a potential acid-base controlling binding molecular device. The binding ratios and association constants between the macrocycle and these benzoate salts were investigated by 1H NMR Job's plot experiments and titration experiment. [ABSTRACT FROM AUTHOR]

Persistent organic pollutants that occur in different environmental matrices create a need for their sensing, removal and remediation [...]

[Display omitted] • A novel sort of macrocyclic CQDs sensor from HemiQ[6] has been developed. • The CQDs sensors exhibited a highly sensitive and real-time response to Pb2+. • The CQDs suggested a potential application for the efficient determination of Pb2+. A macrocyclic compound, hemicucurbit[6]uril (HemiQ[6]), is employed as the carbon source to produce a novel sort of carbon quantum dots (CQDs) with blue fluorescence in aqueous solution. The CQDs are fully identified by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Nuclear Magnetic Resonance (NMR), zeta potential, ultraviolet/visible (UV–vis) and photoluminescence spectroscopy (PL). The nanomaterial is developed for the analysis of Pb2+ in the light of the Resonance Rayleigh scattering (RRS) changes with the increasing Pb2+ concentration. The proposed probe emerges a high selectivity to Pb2+ and excellent sensitivity in the linear concentration range of 0–6 μM with a detection limit low to 0.42 μM, which is superior to the previous values of Pb2+ sensors, as well as the good anti-interference ability is confirmed by the specifical response to Pb2+ in the presence of other metal cations. Therefore, the proposed analysis of Pb2+ is explored for the application in real samples of tap water and lake water, in satisfied results of acceptable recoveries. [ABSTRACT FROM AUTHOR]

A novel hemicucurbituril-based macrocycle, alternately consisting of amidobenzene and 2-imidazolidione moieties was designed and synthesized. Based on the fragment coupling strategy, nitrobenzene-containing hemicucurbituril was firstly prepared facilely under alkaline environment, and reduction of the nitro groups produced the desired amidobenzene-containing hemicucurbituril. As an original fluorescent chemosensor, it exhibited strong interactions with Fe3+ over other metal cations. The experimental evidence of fluorescence spectra suggested that a 1:1 complex was formed between this macrocycle and Fe3+ with an association constant up to (2.1 ± 0.3) × 104 M−1. Meanwhile, this macrocycle showed no obvious or only slight enhancement of the fluorescence intensity with selected anions.

Solid-phase extraction that utilizes selective macrocyclic receptors can serve as a useful tool for removal of chemical wastes. Hemicucurbiturils are known to form inclusion complexes with suitably sized anions; however, their use in selective binding of non-charged species is still very limited. In this study, we found that cyclohexanohemicucurbit[8]uril encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles, which is investigated by single-crystal X-ray diffraction, NMR spectroscopy, isothermal titration calorimetry, and thermogravimetry. The macrocycle acts as a promising selective sorption material for the extraction of sulfur heterocycles, such as 1,3-dithiolane and α-lipoic acid, from water.

This article discusses the use of cyclohexanochemicucurbit[n]urils (cycHC[n]) as molecular containers for the encapsulation of small neutral organic molecules, including environmental pollutants and biologically active compounds. The study confirms the formation of inclusion complexes in the solid state and demonstrates host-guest interactions between cycHC[8] and various hydrophobic neutral heterocycles and haloalkanes in different solvent media. The macrocycle is insoluble in water, but it can selectively capture neutral guests from aqueous solutions. The authors of the article have provided their contributions and declare no conflicts of interest. [Extracted from the article]

A supramolecular catalytic strategy for the synthesis of dibenzo[a,j]phenazine compounds from 2‐arylamines is demonstrated. The dimerization is achieved through the catalytic action of HemiQ[6] in an acidic environment. Kinetic constants and activation energies have been calculated through UV/Vis spectrophotometric investigations using different amounts of HemiQ[6], whereby the reactivity was found to be related to the electron densities of the substrates. A possible mechanism involving host‐guest interaction between a 2‐arylaminium salt and HemiQ[6] through hydrogen‐bonding is proposed. The transformation of 2‐arylamines to dibenzo[a,j]phenazines in the presence of HemiQ[6] suggests that such supramolecular catalysis is effective for such constructions. [ABSTRACT FROM AUTHOR]

In order to investigate the ability of bis(zinc octaethylporphyrin) (bis–ZnOEP) to discriminate cyclohexanohemicucurbit[n]urils (cycHC[n]) of different shapes and sizes, the self-assembly of barrel-shaped chiral cycHC[n] with bis–ZnOEP was studied by various spectroscopic methods (absorption, fluorescence, circular dichroism (CD), and NMR). While the binding of 6-membered cycHC[6] induced a tweezer-like conformation followed by the formation of anti-form of bis–ZnOEP upon further addition of cycHC[6], the interaction of 8-membered cycHC[8] is more complex and proceeds through the featured syn-to-anti conformational change of bis–ZnOEP and further intermolecular self-assembly via multiple noncovalent associations between cycHC[8] and bis–ZnOEP. Whilst bis–porphyrins are known to be effective chemical sensors able to differentiate various guests based on their chirality via induced CD, their ability to sense small differences in the shape and size of relatively large macrocycles, such as chiral cycHC[6] and cycHC[8], is scarcely examined. Both studied complexes exhibited characteristic induced CD signals in the region of porphyrin absorption upon complexation.

[Display omitted] • A supramolecular photoelectrochemical sensor was constructed by rGO, g-C 3 N 4 QDs, and HemiQ[12]. • The recognition for chloramphenicol was achieved by functionalization of the macrocyclic compound. • The sensitive response was reached with synergic enhanced photocurrent by the ternary composites. A novel photoelectrochemical sensor was constructed by ternary layer-by-layer composites of reduced graphene oxide (rGO), graphitic carbon nitride quantum dots (g-C 3 N 4 QDs), and hemicucurbit[12]uril (HemiQ[12]), on the Indium-Tin Oxide (ITO) piece in sequence. Electrochemical Impedance Spectroscopy (EIS) was employed to confirm the successful assembly of the sandwich electrode, and the functionalization of each layer was explored by comparing of the currents with stepwise coating of the materials to achieve the synergistic enhancement of photoelectrochemical intensity. The application of proposed electrode was achieved by ultrasensitive sensing for chloramphenicol (CAP), which provided a limit of detection low to 0.089 nM, with high selectivity, good reproducibility and stability. The acceptable recoveries for the determination of CAP in real samples of honey and milk illustrated the feasibility of the established analytical method. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Enantiorecognition of a chiral analyte usually requires the ability to respond with high specificity to one of the two enantiomers of a chiral compound. However, in most cases, chiral sensors have chemical sensitivity toward both enantiomers, showing differences only in the intensity of responses. Furthermore, specific chiral receptors are obtained with high synthetic efforts and have limited structural versatility. These facts hinder the implementation of chiral sensors in many potential applications. Here, we utilize the presence of both enantiomers of each receptor to introduce a novel normalization that allows the enantio-recognition of compounds even when single sensors are not specific for one enantiomer of a target analyte. For this purpose, a novel protocol that permits the fabrication of a large set of enantiomeric receptor pairs with low synthetic efforts by combining metalloporphyrins with ( R , R )- and ( S , S )-cyclohexanohemicucurbit[8]uril is developed. The potentialities of this approach are investigated by an array of four pairs of enantiomeric sensors fabricated using quartz microbalances since gravimetric sensors are intrinsically non-selective toward the mechanism of interaction of analytes and receptors. Albeit the weak enantioselectivity of single sensors toward limonene and 1-phenylethylamine, the normalization allows the correct identification of these enantiomers in the vapor phase indifferent to their concentration. Remarkably, the achiral metalloporphyrin choice influences the enantioselective properties, opening the way to easily obtain a large library of chiral receptors that can be implemented in actual sensor arrays. These enantioselective electronic noses and tongues may have a potential striking impact in many medical, agrochemical, and environmental fields.

Hemicucurbituril supported ionic liquid phase catalyst (HmCucSILP) has been synthesized by anchoring multilayer of ionic liquid ([Bmim]Cl) containing Pd(OAc) and X-phos on the surface of hemicucurbit[6]uril. The HmCucSILP was effectively employed in intermolecular C-O coupling of aryl halides with sodium alkoxides for the synthesis of alkyl aryl ethers. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The host-guest interactions of hemicucurbit[6 and 12]urils with the Schiff base guest 1 has been investigated. H 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) × 10 and (5.5 ± 0.8) × 10 L mol, respectively, via non-linear curve fitting, which indicate that the formation of hydrogen bondings are important in the host-guest interactions. [ABSTRACT FROM AUTHOR]

The host-guest interactions between hemicucurbit[6 and 12]urils and o-, m-, and p-aminophenols have been investigated by means of H NMR spectrometry, fluorescence emission spectroscopy, and isothermal titration calorimetry. The H 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. Graphical Abstract: Formation of interaction complexes of aminophenols with hemicucurbit[6 and 12] in organic solvent have been investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method for synthesis of hybrid thiohemicucurbiturils has been efficiently developed. • Some carbonyl groups at the portal position of hemicucurbituril are replaced by thiono group. • Contrary to the acid condition for synthesis of traditional hemicucurbiturls, this method provides a moderate condition without acid and base. • This method provides a potential platform for modular synthesis of novel hybrid hemicucurbiturl derivatives with various motifs. A method for synthesis of hybrid thiohemicucurbiturils has been developed. With this method, three novel thiohemicucurbiturils have been constructed. Contrary to the acid condition for synthesis of traditional hemicucurbiturls, this method provides a moderate condition which is compatible for more complicated structure in synthesis of novel hybrid hemicucurbiturils. [ABSTRACT FROM AUTHOR]

In order to investigate the ability of bis(zinc octaethylporphyrin) (bis–ZnOEP) to discriminate cyclohexanohemicucurbit[n]urils (cycHC[n]) of different shapes and sizes, the self-assembly of barrel-shaped chiral cycHC[n] with bis–ZnOEP was studied by various spectroscopic methods (absorption, fluorescence, circular dichroism (CD), and NMR). While the binding of 6-membered cycHC[6] induced a tweezer-like conformation followed by the formation of anti-form of bis–ZnOEP upon further addition of cycHC[6], the interaction of 8-membered cycHC[8] is more complex and proceeds through the featured syn-to-anti conformational change of bis–ZnOEP and further intermolecular self-assembly via multiple noncovalent associations between cycHC[8] and bis–ZnOEP. Whilst bis–porphyrins are known to be effective chemical sensors able to differentiate various guests based on their chirality via induced CD, their ability to sense small differences in the shape and size of relatively large macrocycles, such as chiral cycHC[6] and cycHC[8], is scarcely examined. Both studied complexes exhibited characteristic induced CD signals in the region of porphyrin absorption upon complexation. [ABSTRACT FROM AUTHOR]

A novel hemicucurbituril-based macrocycle, alternately consisting of amidobenzene and 2-imidazolidione moieties was designed and synthesized. Based on the fragment coupling strategy, nitrobenzene-containing hemicucurbituril was firstly prepared facilely under alkaline environment, and reduction of the nitro groups produced the desired amidobenzene-containing hemicucurbituril. As an original fluorescent chemosensor, it exhibited strong interactions with Fe 3+ over other metal cations. The experimental evidence of fluorescence spectra suggested that a 1:1 complex was formed between this macrocycle and Fe 3+ with an association constant up to (2.1 ± 0.3) × 10 4 M -1 . Meanwhile, this macrocycle showed no obvious or only slight enhancement of the fluorescence intensity with selected anions., (Copyright © 2021, Zeng et al.)

Solid-phase extraction that utilizes selective macrocyclic receptors can serve as a useful tool for removal of chemical wastes. Hemicucurbiturils are known to form inclusion complexes with suitably sized anions; however, their use in selective binding of non-charged species is still very limited. In this study, we found that cyclohexanohemicucurbit[8]uril encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles, which is investigated by single-crystal X-ray diffraction, NMR spectroscopy, isothermal titration calorimetry, and thermogravimetry. The macrocycle acts as a promising selective sorption material for the extraction of sulfur heterocycles, such as 1,3-dithiolane and α -lipoic acid, from water., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Shalima, Mishra, Kaabel, Ustrnul, Bartkova, Tõnsuaadu, Heinmaa and Aav.)