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In this paper, a thiacalix[4]arene complex [Zn2(TIT4A)L2]·4DMF·2CH3OH (H2L = 4,4′-oxybisbenzoic acid) (Zn-TIT4A-L) was synthesized by a solvothermal method. The composites were prepared by combining Zn-TIT4A-L with reduced graphene oxide (RGO), mesoporous carbon (MC), and multi-walled carbon nanotubes (MWCNTs), respectively. Three representative composites are Zn-TIT4A-L@RGO(1:1), Zn-TIT4A-L@MC(1:2), and Zn-TIT4A-L@MWCNT(1:2). X-ray diffraction and scanning electron microscopy characterized their structures and morphologies. The results showed that three composites were successfully prepared, and the crystals of the complex remained in the composites. The electrochemical properties of the composites were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The results indicated that they had good electrocatalytic activity and conductivity. Among them, Zn-TIT4A-L@RGO(1:1) had the best performance and was used for the quantitative detection of flutamide (FTA). The linear range of detection is 0.1–200 μM, and the limit of detection is 0.015 μM. At the same time, the sensor also had good reproducibility, anti-interference, and stability. The sensor was also used for the detection of FTA in lake water, human urine, and serum with a satisfactory recovery rate. The possible mechanism of electrochemical detection of FTA was also discussed.

The design of artificial receptors with a specific recognition function and enhanced selectivity is highly desirable in the electrochemical sensing field, which can be used for detection of environmental pollutants. In this facet, metal–organic frameworks (MOFs) featured adjustable porosities and specific host-guest recognition properties. Especially, the large hydrophobic cavity formed in the porous MOFs may become a potential artificial receptor. We herein designed a new porous MOF [Zn2(L)(IPA)(H2O)]·2DMF·2MeOH·3H2O (Zn-L-IPA) by using a functionalized sulfonylcalix[4]arene (L1) and isophthalic acid (H2IPA) (DMF = N,N′-dimethylformamide). The specific pore size and pore shape of Zn-L-IPAmade it efficiently selective for absorption of bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS). Therefore, a rapid, highly selective, and ultrasensitive electrochemical sensing platform Zn-L-IPA@GP/GCEwas fabricated by using Zn-L-IPAas a host to recognize and absorb bisphenol guests (GP= graphite powder, GCE= glassy carbon electrode). Most strikingly, the extremely low detection limits were up to 3.46 and 0.17 nM for BPAand BPF, respectively, using the Zn-L-IPA@GP/GCEelectrode. Furthermore, the “recognition and adsorption” mechanism was uncovered by density functional theory with the B3LYP function. This work offered a prospective strategy for selective absorption and detection of harmful bisphenols with the MOF-based porous material.

Conductive metal–organic frameworks (MOFs) have a wide range of applications in supercapacitors, electrocatalysts, and fuel cells, while gas-driven conductive MOFs have not yet been synthesized so far. Herein, we report a gas-driven conductive MOF (A) constructed from calix[4]resorcinarene macrocycle and Co(II) cations, which shows the conductivity enhancement by about eight orders of magnitude through NO2adsorption. The conductivities of MOF Abefore and after the adsorption of NO2were calculated to be about 1.3 × 10–11and 8.4 × 10–4S/cm, respectively. MOF Arealizes the conversion from an insulator to a conductor by adsorbing NO2. When NO2is evacuated, MOF Aquickly changes from a conductor back to an insulator in 42 s. In the crystal structure of NO2-adsorbed MOF (termed as A-NO2), NO2molecule connects Co(II) and uncoordinated carboxylate groups through hydrogen-bonding interactions to form a conductive pathway, greatly reducing the electron transmission distance between each two metal clusters. In addition, NO2molecule and H3O+may also form a conductive pathway by hydrogen-bonding interactions. This work presents an interesting macrocycle-based MOF with a NO2-driven on/off conductivity switch, proving the possibility for designing advanced gas-driven conductive systems.

By employing a bowl-like tetra(benzimidazole)resorcin[4]arene (TBR4A) ligand, two new polyoxometalate-templated metal–organic frameworks (POMOFs), [Co8Cl14(TBR4A)6]·3[H3.3SiW12O40]·10DMF·11EtOH·20H2O (1) and [Co3Cl2(TBR4A)2(DMF)4]·[SiW12O40]·2EtOH·3H2O (2), have been prepared under solvothermal conditions (DMF = N,N′-dimethylformamide). 1shows a 2D cationic layer, whereas 2exhibits a 3D framework. Remarkably, the Keggin POMs in 1and 2were located in the cavities formed by two bowl-like resorcin[4]arenes in sandwich fashions. Their framework structures were highly dependent on the coordination modes of the TBR4A ligands. To increase the conductivity of POMOFs, the samples of 1and 2were loaded on the conductive polypyrrole-reduced graphene oxide (PPy-RGO) viaball milling (1@PGand 2@PG). Then, the obtained composites experienced calcination at a proper temperature to produce 1@PG-Aand 2@PG-A. The resulting 1@PG-Aand 2@PG-Acomposites, with improved conductivities, uniform sizes and micropores, exhibited promising electrochemical performance for lithium-ion batteries. We herein proposed a size-controlled route for the rational fabrication of functional POMOFs and their usage in energy fields.

Self-assembly of polyoxometalates, transition metal salts, and 2,6-bis(2′-pyridyl)-4-hydroxypyridine (LOH) obtained four organic–inorganic hybrids [Co2.5(LOH)(LO)2(H2O)2(PW12O39)]·3CH3CN·2OH (1), [Zn1.5(LOH)3]·(PMo12O40)·CH3OH·2H2O (2), [Cd1.5(LOH)3]·(PW12O40)·2CH3OH·1.5H2O (3), and [Mn(LOH)2]·(PW12O40)·2CH3CN·H3O (4). Hybrid 1exhibits an extended chain, which could be further connected into a 3D supramolecular architecture by H-bonds. Hybrids 2–4feature monomolecular structures, which are further bridged via H-bonds to yield charming 3D supramolecular structures. Noteworthy, 1and 2can be employed as recyclable and highly efficient heterogeneous catalysts. The activated 1displays a high catalytic activity for the cycloaddition reaction of CO2and epoxides. Hybrid 2exhibits an excellent catalytic performance for the oxidative desulfurization reaction.

The design and assembly of polyoxometalate-resorcin[4]arene-based metal–organic molecular materials are particularly attractive for their elegant structures and potential functions. By applying a newly designed resorcin[4]arene ligand (TPC4R-II), a copper(I)-coordinated polyoxometalate-based metal–organic molecular material, namely, [CuI6(Br)3(TPC4R-II)3(PMo12O40)]·8H2O (1), was rationally assembled. Three copper(I)-coordinated resorcin[4]arenes are held together by a central [PMo12O40]3–to yield a supramolecular propeller. 1features efficient catalytic performances for oxidation desulfurization (ODS) and azide–alkyne cycloaddition (AAC) reactions. This work affords a feasible method for the nanosized polyoxometalate-based metal-resorcin[4]arene assemblies by well combinating two types of large composites as well as low coordination metal cations.

The design and synthesis of effective and recyclable oxidative desulfurization catalysts is of great importance in view of environmental protection and human health. Herein, a family of polyoxomolybdate-based inorganic–organic hybrid materials, namely, [Mn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (1), [Ni(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (2), [Zn(TMR4A)(H2O)4][Mo6O19]·0.5CH3CH2OH·H2O (3), and [Co2(TMR4A)2(H2O)4(β-Mo8O26)]·CH3CN·12H2O (4), were assembled by the functionalized resorcin[4]arene ligand (TMR4A) with polyoxomolybdate and metal ions under solvothermal conditions. In isostructural 1–3, the [M(TMR4A)(H2O)4]2+species (M = MnII, NiII, ZnII) and [Mo6O19]2–anions are held together via C–H···O hydrogen bonds to give a 3D supramolecular architecture. In 4, two [Co(TMR4A)(H2O)2]2+cations were linked by one [β-Mo8O26]4–anion to produce an attractive molecular dimer. Remarkably, 1–4, as recyclable heterogeneous catalysts, exhibit efficient catalytic oxidation desulfurization activities toward thioethers. Particularly, 1, as a representative example, features selective catalytic oxidation for sulfur mustard simulant. Moreover, their electrochemical properties were also studied.

The design and synthesis of polynuclear metal cluster-based coordination cages is of considerable interest due to their appealing structural characteristics and potential applications. Herein, we report a calix[4]resorcinarene-based [Co12] coordination cage, [Co12(TPC4R-I)2(1,3-BDC)10(μ3-OH)4(H2O)10(DMF)2]·7DMF·23H2O (1), assembled with 2 bowl-shaped calix[4]resorcinarenes (TPC4R-I), 10 angular 1,3-benzenedicarboxylates (1,3-BDC), and 12 Co(II) cations. Remarkably, it is shown to be a highly efficient recyclable heterogeneous catalyst for CO2conversion due to its exposed Co(II) Lewis acid sites.

Two remarkable polyoxometalate-bridged Cu(I)- and Ag(I)-thiacalix[4]arene dimers, namely, [Cu4(SiW12O40)(L)2(DMF)2]·2EtOH·DMF (1-Cu) and [Ag4(PMo12O40)(L)2]·OH (1-Ag), were prepared by using a new thiacalix[4]arene, metal cation and polyoxometalate (L = tetra[2-(ethylthio)-1-methyl-1H-imidazole]-thiacalix[4]arene). In 1-Cuand 1-Ag, two thiacalix[4]arenes were linked together by one [SiW12O40]4–or [PMo12O40]3–anion via two metal cations to give a molecular dimer. Further, adjacent dimers were extended into a high-dimensional supramolecular architecture through hydrogen bonds. Markedly, these molecular dimers are exceedingly stable in organic solvents and then were employed as efficient catalysts for catalytic oxidation desulfurization as well as the azide–alkyne “click” reaction.

Self-assembly of resorcin[4]arene-based coordination cages involving more than two resorcin[4]arenes poses significant challenges for the requirements of suitable functionalized resorcin[4]arene ligands and metals. Here, we report an unusual example of a metal-coordinated, resorcin[4]arene-based molecular trimer (1-NO3), composed of three resorcin[4]arenes and three Cd(II) cations. In particular, 1-NO3features efficient and selective removal of environmentally toxic dichromate (Cr2O72–) anions. Moreover, the Knoevenagel condensation reaction was also explored by using 1-NO3as an efficient heterogeneous catalyst.

In this work, we report a new polyoxovanadate–resorcin[4]arene-based metal–organic framework (PMOF), [Co2L0.5V4O12]·3DMF·5H2O (1), assembled with a newly functionalized wheel-like resorcin[4]arene ligand (L). 1features an elegant porous motif and represents a rare example of PMOFs composed of both a resorcin[4]arene ligand and polyoxovanadate. Remarkably, 1shows open V sites in the channel, which makes 1an efficient heterogeneous Lewis acid catalyst for the cycloaddition of carbon dioxide to epoxides with high conversion and selectivity. Strikingly, 1also exhibits high catalytic activity for the heterogeneous oxidative desulfurization of sulfides. Particularly, the heterogeneous catalyst 1can be easily separated and reused with good catalytic activity.

Seven new coordination polymers, namely, [Cd(Tipa)(L1)2]·H2O (1), [Cd(Tipa)(L2)]·H2O (2), [Cd(Tipa)(L2)]·CH3OH·H2O (3), Cd(Tipa)(L3)(H2O) (4), [Mn(Tipa)(L2)]·H2O (5), [Ni2(Tipa)2(L4)(H2O)2]2·Cl4·4H2O (6), and [Ni2(Tipa)2(L5)(H2O)4]·(H4L5)·0.5H2O (7), where HL1 = benzoic acid, H2L2 = 5-NH2-1,3-benzenedicarboxylic acid, H2L3 = 2-(4-carboxybenzylamino)benzoic acid, H2L4 = 1,4-benzenedicarboxylic acid, H4L5 = 1,2,4,5-benzenetetracarboxylic acid, and Tipa = tri(4-imidazolylphenyl)amine, have been synthesized by varying the carboxylate anions and metal centers under hydrothermal conditions. Compound 1shows a one-dimensional (1D) chain. Compounds 2and 5are isostructural and display (3,5)-connected (42·6)(42·67·8) topology. In the two compounds, the identical 2D networks entangle in highly rare parallel fashions to give fascinating 2D → 3D frameworks with polycatenation and polyrotaxane characters. Compound 3displays a 2-fold interpenetrating 3D framework with (3,5)-connected (63)(65·85) topology. The structure of 4is a 4-fold interpenetrating 3D (10,3)-b framework. 6is an uncommon 4-fold interpenetrating 3D framework with (3,4)-connected (4·82)(4·85) topology. 7exhibits an unprecedented 2D → 2D polyrotaxane layer with (3,4)-connected (42·6)(42·63·8) topology. The IR spectra, elemental analyses, and luminescent properties for the compounds were also investigated.

A new highly stable copper(I)-based metal–organic framework (MOF), namely, [CuI4(SiW12O40)(L)]·6H2O·2DMF (1), was synthesized by incorporating Keggin-type polyoxometalate (POM) anions and a functionalized wheel-like resorcin[4]arene-based ligand (L) under sovothermal condition. 1exhibits a charming 3D supramolecular architecture sandwiched by the POM anions. Noticeably, 1has exceptional chemical stability, especially in organic solvents or aqueous solutions with a wide range of pH values. Considering the catalytically active Cu(I) sites in 1, the azide–alkyne cycloaddition (AAC) reaction was studied by employing 1as the heterogeneous catalyst. Most strikingly, 1exhibits excellent catalytic activity as well as recyclability for the AAC reaction.

Six coordination polymers based on three related flexible bis-[(pyridyl)-benzimidazole] ligands and different carboxylates, namely, [Zn2(m-BDC)2(L1)]·2H2O (1), [Zn2(p-BDC)2(L1)(H2O)2] (2), [Zn2(m-BDC)2(L2)]·2.25H2O (3), [Zn2(p-BDC)2(L2)]·CH3OH (4), [Zn2(m-BDC)2(L3)]·2H2O (5), and [Zn2(p-BDC)2(L3)]·2CH3OH (6), where L1= 1,1′-(1,4-butanediyl)bis[2-(2-pyridyl)benzimidazole], L2= 1,1′-(1,6-hexanediyl)bis[2-(2-pyridyl)benzimidazole], L3= 1,1′-(1,10-decanediyl)bis[2-(2-pyridyl)benzimidazole], m-BDC = m-benzenedicarboxylate anion, and p-BDC = p-benzenedicarboxylate anion, have been synthesized under solvothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses and infrared (IR) spectra. Compound 1shows a one-dimensional (1D) double chain which extends into a two-dimensional (2D) supramolecular sheet by π−πinteractions. Polymers 2−4display similar 2D layer structures with 3-connected 63topologies. In 2and 3, the adjacent layers are further connected through π−πinteractions to form three-dimensional (3D) supramolecular structures. However, in 4, two identical layers penetrate each other in parallel modes to give a 2-fold parallel interpenetrating net. Compounds 5and 6show 2-fold interpenetrating networks with α-Po topological structures. A systematic structural comparison of these complexes indicates that the different lengths of the bis-[(pyridyl)-benzimidazole] ligands (L1−L3) are important for the formation of the different structures. In addition, the luminescent properties of L1−L3and 1−6have been studied in the solid state at room temperature.

Chlorpromazine (CPMZ) is a representative drug for the treatment of psychiatric disorders. Excessive use of CPMZ could result in some serious health problems, and therefore, construction of a sensitive electrochemical sensor for CPMZ detection is greatly significant for human health. Herein, a feasible electrochemical method for the detection of CPMZ was provided. To design a suitable electrode surface modifier, a new two-dimensional (2D) thiacalix[4]arene-based metal–organic framework was designed and synthesized under solvothermal conditions, namely, [Co(TMPA)Cl2]MeOH·2EtOH·2H2O (Co-TMPA). Afterward, a series of composite materials was prepared by combining Co-TMPA with highly conductive carbon materials. Markedly, Co-TMPA/MWCNT-2@GCE (GCE = glassy carbon electrode, MWCNT = multiwalled carbon nanotube) exhibited the best electrocatalytic performance for CPMZ detection due to the synergistic effect between MWCNT and Co-TMPA. Particularly, it featured a low limit of detection (8 nM) and a wide linear range (0.05 to 1350 μM) in quantitative determination of CPMZ. Meanwhile, the sensor possessed excellent stability, selectivity, and reproducibility. Importantly, Co-TMPA/MWCNT-2@GCE was employed to analyze CPMZ in urine and serum with satisfactory recoveries (98.87–102.17%) and relative standard deviations (1.44–3.80%). Furthermore, the electrochemical detection accuracy of the Co-TMPA/MWCNT-2@GCE sensor was verified with the ultraviolet–visible spectroscopy technique. This work offers a promising sensor for the efficient analysis of drug molecules.

Two new inorganic–organic hybrid complexes, namely, {[Co4(L)2(HCOO)2(OH)2][SiO4(W3O9)4]}·6DMF·5H2O (1) and {[Zn4(L)2(HCOO)2(OH)2][SiO4(W3O9)4]}·6DMF·5H2O (2), have been solvothermally prepared by using a new methyl imidazole functionalized resorcin[4]arene (L), polyoxometalate (POM), and metal cation. Isostructural 1and 2feature porous supramolecular architectures and represent an unusual example of a successful combination of resorcin[4]arenes with polyoxometalates. Remarkably, selective adsorptions for organic dyes were studied by using 1and 2as adsorbents. Moreover, their electrocatalytic activities for the oxidation of ascorbic acid and reduction of NaBrO3were also studied.

Effective and selective capture of environmentally toxic Cr2O72–from water is desirable for both environment protection and human health, but it still remains a significant challenge. We present a water-stable cationic metal–organic framework (MOF) with large nanotubular channels (ca. 1.4 × 1.4 nm2), (1-Cl). Remarkably, the resulting porous material exhibits rapid aqueous-phase removal of Cr2O72–via an anion-exchange manner. Meaningfully, the capture and separation of aqueous Cr2O72–are highly selective even in the presence of other disturbing anions. More importantly, the crystal structure of 1-Clafter anion exchange (1-Cr2O7) could be determined by single crystal X-ray diffraction, elaborating the single-crystal-to-single-crystal (SC-SC) transformation. The Cr2O72–removal process by 1-Clthus was directly uncovered by the crystal structure of Cr2O72–-incorporated 1-Cr2O7.

A stable microporous anionic metal–organic framework (MOF), [(CH3)2NH2]6[Cd3L(H2O)2]·12H2O (1), has been synthesized via solvothermal assembly of a new resorcin[4]arene-functionalized dodecacarboxylic acid (H12L) and Cd(II) cations. The constructed MOF (1) was characterized by single-crystal X-ray diffraction and other physicochemical analyses. 1exhibits a fascinating 3D microporous framework structure, in which the free water molecules and the [(CH3)2NH2]+cations were located. Remarkably, the exposed Lewis acid Cd(II) sites of activated 1make it an efficient heterogeneous catalyst for the cycloaddition of CO2with epoxides at 1 and 20 atm. Importantly, the activated samples of 1can be reused at least five circles with excellent catalytic performance. Moreover, the fluorescence detection of Cr2O72–and Fe3+was studied by using 1as a potential luminescent sensor.

We herein report the porous 4-fold interpenetrated mog(moganite) metal–organic framework (MOF) [Cd3(tipp)(bpdc)2]·DMA·9H2O (1·Cd; H2tipp = 5,10,15,20-tetrakis(4-(imidazol-1-yl)phenyl)porphyrin, H2bpdc = biphenyl-4,4′-dicarboxylic acid, DMA = N,N′-dimethylacetamide). The incorporation of Cd and carboxylate oxygen affords 1·Cdrich Lewis acid and basic sites. This MOF 1·Cdwas then applied as an efficient heterogeneous catalyst for the important cyanosilylation of aldehydes and Knoevenagel condensation reactions. 1·Cdfeatures excellent catalytic performance and recyclability for the cyanosilylation of various aldehydes with trimethylsilyl cyanide (TMSCN). Moreover, 1·Cdshows highly efficient catalysis and substrate selectivity for Knoevenagel condensation reactions of various aldehydes with malononitrile. The high catalytic activity and stability toward C–C bond formation make 1·Cda promising heterogeneous catalyst.

Previous studies have demonstrated altered metabolites in samples of Alzheimer’s disease (AD) patients. However, the sample size from many of them is relatively small and the metabolites are relatively limited. Here we applied a comprehensive platform using ultraperformance liquid chromatography-time-of-flight mass spectrometry and gas chromatography-time-of-flight mass spectrometry to analyze plasma samples from AD patients, amnestic mild cognitive impairment (aMCI) patients, and normal controls. A biomarker panel consisting of six plasma metabolites (arachidonic acid, N,N-dimethylglycine, thymine, glutamine, glutamic acid, and cytidine) was identified to discriminate AD patients from normal control. Another panel of five plasma metabolites (thymine, arachidonic acid, 2-aminoadipic acid, N,N-dimethylglycine, and 5,8-tetradecadienoic acid) was able to differentiate aMCI patients from control subjects. Both biomarker panels had good agreements with clinical diagnosis. The 2 panels of metabolite markers were all involved in fatty acid metabolism, one-carbon metabolism, amino acid metabolism, and nucleic acid metabolism. Additionally, no altered metabolites were found among the patients at different stages, as well as among those on anticholinesterase medication and those without anticholinesterase medication. These findings provide a comprehensive global plasma metabolite profiling and may contribute to making early diagnosis as well as understanding the pathogenic mechanism of AD and aMCI.