Hybrid nanocomposites based on Cu-BTC MOF, graphene oxide (GO), carbon nanotubes (CNTs), and Fe3O4 magnetic nanoparticles (MNPs) were developed via a simple green solvothermal method, at which GO and CNT were used as platforms to load nanostructured Cu-BTC MOF and Fe3O4 MNPs. The as-synthesized hybrid nanocomposites were characterized by XRD, SEM, TEM, XPS, IR, Raman, TGA, and BET techniques. XRD measurements show highly crystalline structures for the prepared hybrid nanocomposites. Morphological analyses carried out by SEM and TEM also confirm successful growth of Fe3O4 MNPs and nanoparticulate Cu-BTC MOF over the carbon-based platforms. Chemical, elemental, and TGA analyses verify chemical bonding and successful compositing of the parent materials. Nitrogen isotherms show a cumulative pore volume of 0.360 cm 3 g-1 for the hybrid nanocomposite of Fe3O4/Cu-BTC@GO compared to 0.030 cm 3 g-1 of the sole Cu-BTC MOF, which suggests potential uses towards small molecule adsorption. We have found that use of GO and CNT substrates (i) diminish the aggregation and increases dispersive forces within the MOFs, (ii) lead to MOFs with different morphology and size, and (iii) result in formation of small pores between the MOF and the platforms. Adsorption capacity of the prepared nanomaterials was examined over methylene blue (MB) as a model organic pollutant. The developed hybrid nanomaterials show enhanced pollutant adsorption capacity compared to that of the parent materials. The improved adsorption capacity is attributed to the synergetic effect of covalent bonding between the parent materials as well as to the unique features of the nanoscale MOF. Overall, these novel materials may be considered as excellent candidates towards a variety of environmental applications such as water remediation.
Red light has the advantages of low energy, less health risk and high penetration depth through various media. Herein, a helical carbenium ion (N,N'-din -propyl-1,13-dimethoxyquinacridinium (nPr-DMQA+) tetrafluoroborate) has been used as an organic photoredox catalyst for photoreductions and photooxidations in the presence of red ligh (max = 640 nm). It has catalyzed red-lightmediated dual transition-metal/photoredox-catalyzed C-H arylation and intermolecular atom transfer radical addition through oxidative quenching, affording products in 57-93% yields. Moreover, its potential in photooxidation catalysis has also been demonstrated by successful applications in red-light-induced aerobic oxidative hydroxylation of arylboronic acids and benzylic C(sp3)-H oxygenation through reductive quenching, delivering products in up to 92% yield. Thus, a versatile organic photoredox catalyst (helical carbenium ion) for red-light-mediated photoredox reactions has been developed. In summary, we have disclosed a helical carbenium ion [nPr-DMQA+][BF4-] (3), which catalyzes photoreductions and photooxidations in the presence of low-energy red light. The role of 3 as an efficient PC in oxidative and reductive quenching were evaluated by transition-metal/nPr-DMQA+-catalyzed C-H arylations and intermolecular ATRA (oxidative quenching), as well as aerobic oxidative hydroxylation of arylboronic acids and benzylic C(sp3)-H oxygenation (reductive quenching). Eight diverse substrates were well-tolerated for red-light-mediated dual Pd/nPr-DMQA+-catalyzed C(sp2)-H arylation. Moreover, with twelve different arylboronic acids as the substrates, red-lightinduced nPr-DMQA+-catalyzed aerobic oxidative hydroxylation proceeded smoothly as well. The successful applications of 3 in these red-light-mediated reactions have established its role as a versatile organic PC, which can serve as a complementary option for current white, blue or green-light-mediated photocatalysis. Further investigations on the applications of 3 towards more challenging photoredox catalysis are in progress.
Redox flow batteries (RFBs) represent a promising technology for grid-scale integration of renewable energy. However, crosscontamination problems, encountered with distinct catholyte and anolyte, limit the development of reliable organic RFBs. Herein, we report the first use of a helical carbocation with three oxidation states, for the development of symmetric cells. Essential kinetic properties of this molecule were assessed by cyclic voltammetry. Its stability was then evaluated by mono-and bielectronic cycling experiments, resulting in 550 and 80 cycles respectively, with high-capacity retention. This helical ion-based electrolyte achieved a proof-of-principle 2.12 V open circuit potential as an all-organic nonaqueous symmetric RFB.
We report the reactivity between the Lewis acidic trioxatriangulenium ion (TOTA+) and a series of Lewis bases such as phosphines and N-heterocyclic carbene (NHC). The nature of the Lewis acid-base...
We report a series of tunable and persistent [4]-helicene neutral radicals by chemical reduction of the [4]-helicenium cation analogue. EPR spectroscopy and DFT calculations indicate that the unpaired electron is localized at the central carbon atom.
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