Uranium is a key resource for the development of the nuclear industry, and extracting uranium from the natural seawater is one of the most promising ways to address the shortage of uranium resources. ...Herein, a semiconducting covalent organic framework (named NDA‐TN‐AO) with excellent photocatalytic and photoelectric activities was synthesized. The excellent photocatalytic effect endowed NDA‐TN‐AO with a high anti‐biofouling activity by generating biotoxic reactive oxygen species and promoting photoelectrons to reduce the adsorbed UVI to insoluble UIV, thereby increasing the uranium extraction capacity. Owing to the photoinduced effect, the adsorption capacity of NDA‐TN‐AO to uranium in seawater reaches 6.07 mg g−1, which is 1.33 times of that in dark. The NDA‐TN‐AO with enhanced adsorption capacity is a promising material for extracting uranium from the natural seawater.
Photoelectric and photocatalytic effects endow the covalent organic framework NDA‐TN‐AO with good anti‐biofouling activity. This occurs by generating biotoxic reactive oxygen species and promoting photoelectrons to reduce the adsorbed UVI to insoluble UIV, thereby improving the uranium adsorption capacity.
Integrating the advantages of homogeneous and heterogeneous catalysis has proved to be an optimal strategy for developing catalytic systems with high efficiency, selectivity, and recoverability. ...Supramolecular metal‐organic cages (MOCs), assembled by the coordination of metal ions with organic linkers into discrete molecules, have performed solvent processability due to their tunable packing modes, endowing them with the potential to act as homogeneous or heterogeneous catalysts in different solvent systems. Here, the design and synthesis of a series of stable {Cu3} cluster‐based tetrahedral MOCs with varied packing structures are reported. These MOCs, as homogeneous catalysts, not only show high catalytic activity and selectivity regardless of substrate size during the CO2 cycloaddition reaction, but also can be easily recovered from the reaction media through separating products and co‐catalysts by one‐step work‐up. This is because that these MOCs have varied solubilities in different solvents due to the tunable packing of MOCs in the solid state. Moreover, the entire catalytic reaction system is very clean, and the purity of cyclic carbonates is as high as 97% without further purification. This work provides a unique strategy for developing novel supramolecular catalysts that can be used for homogeneous catalysis and recycled in a heterogeneous manner.
A series of {Cu12} based tetrahedral (Td) metal‐organic cages (MOCs) with varied packing modes are self‐assembled, which act as highly active homogeneous catalysts for CO2 cycloaddition with epoxides. The varied packing of Td cages from hexagonal to cubic mode in the MOC enables one‐step heterogenous separation of the catalyst, co‐catalyst, and product, which perfectly bridges the homogeneous and heterogeneous catalysis.
Stimuli‐responsive circularly polarized luminescence (CPL) materials are ideal for information anti‐countering applications, but the best‐performing materials have not yet been identified. This work ...presents enantiomorphic hybrid antimony halides R‐(C5H12NO)2SbCl5 (1) and S‐(C5H12NO)2SbCl5 (2) showing mirror‐imaged CPL activity with a dissymmetry factor of 1.2×10−3. Interestingly, the DMF‐induced structural transformation is realized to obtain non‐emissive R‐(C5H12NO)2SbCl5 ⋅ DMF (3) and S‐(C5H12NO)2SbCl5 ⋅ DMF (4) upon exposure to DMF vapor. The transformation process is reversed upon heating. DFT calculations showed that the DMF‐induced‐quenched‐luminescence is attributed to the intersection of the ground and excited state curves on the configuration coordinates. Unexpectedly, the nanocrystals of the chiral antimony halides 1 and 2 were prepared and indicate the excellent solution process performance. The reversible PL and CPL switching gives the system applications in information technology, anti‐counterfeiting, encryption‐decryption, and logic gates.
The chiral hybrid antimony halides R‐/S‐(C5H12NO)2SbCl5 have excitation‐dependent emission originating from the synergistic effects of ligand and self‐trapped excitons, and exhibit reversible structural transformation between non‐emissive R‐/S‐(C5H12NO)2SbCl5 ⋅ DMF upon exposure to DMF and heat. CPL switch, chiral optical logic gate and anti‐counterfeiting applications have been investigated based on the multiple stimuli‐responsive properties.
A cationic sliver-triazolate MOF displays an efficient function of Cr(VI) removal via anion exchange.
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•The anion-exchange pattern of the silver-triazolate MOF has been ...established.•Hofmeister bias has been invoked to explain the experimental results.•The MOF possesses a good function of Cr(VI)-removal from water.
Gram-scale synthesis of a silver-triazolato framework − {Ag8(tz)6(NO3)2·6H2O}n (1-NO3; tz−=3,5-diphenyl-1,2,4-triazolate) − has been achieved, enabling the systematic investigation of its anion-exchange properties. Our experimental results show that the anion-exchange pattern of 1-NO3 conforms to the so-called Hofmeister bias, which has been correlated to the hydrophobic nature of the MOF pores, and can be understood by considering the difference between the hydration energies of the exchanging anions. Furthermore, 1-NO3 displays a fast, efficient, and reversible adsorption of HCrO4− (via anion-exchange) from Cr(VI)-containing aqueous solution (Qmax=37.0 Cr mg/g, 303K), rendering it a promising prototype of a recyclable MOF for Cr(VI) removal.
Constructing redox semiconductor heterojunction photocatalysts is the most effective and important means to complete the artificial photosynthetic overall reaction (i.e., coupling CO
photoreduction ...and water photo-oxidation reactions). However, multiphase hybridization essence and inhomogeneous junction distribution in these catalysts extremely limit the diverse design and regulation of the modes of photogenerated charge separation and transfer pathways, which are crucial factors to improve photocatalytic performance. Here, we develop molecular oxidation-reduction (OR) junctions assembled with oxidative cluster (PMo
, for water oxidation) and reductive cluster (Ni
, for CO
reduction) in a direct (
-OR), alternant (
-OR), or symmetric (
-OR) manner, respectively, for artificial photosynthesis. Significantly, the transfer direction and path of photogenerated charges between traditional junctions are obviously reformed and enriched in these well-defined crystalline catalysts with monophase periodic distribution and thus improve the separation efficiency of the electrons and holes. In particular, the charge migration in
-OR shows a periodically and continuously opposite mode. It can inhibit the photogenerated charge recombination more effectively and enhance the photocatalytic performance largely when compared with the traditional heterojunction models. Structural analysis and density functional theory calculations disclose that, through adjusting the spatial arrangement of oxidation and reduction clusters, the energy level and population of the orbitals of these OR junctions can be regulated synchronously to further optimize photocatalytic performance. The establishment of molecular OR junctions is a pioneering important discovery for extremely improving the utilization efficiency of photogenerated charges in the artificial photosynthesis overall reaction.
In modern industries, the aerobic oxidation of C(sp
)-H bonds to achieve the value-added conversion of hydrocarbons requires high temperatures and pressures, which significantly increases energy ...consumption and capital investment. The development of a light-driven strategy, even under natural sunlight and ambient air, is therefore of great significance. Here we develop a series of hetero-motif molecular junction photocatalysts containing two bifunctional motifs. With these materials, the reduction of O
and oxidation of C(sp
)-H bonds can be effectively accomplished, thus realizing efficient aerobic oxidation of C(sp
)-H bonds in e.g., toluene and ethylbenzene. Especially for ethylbenzene oxidation reactions, excellent catalytic capacity (861 mmol g cat
) is observed. In addition to the direct oxidation of C(sp
)-H bonds, CeBTTD-A can also be applied to other types of aerobic oxidation reactions highlighting their potential for industrial applications.
Polyoxometalates (POMs), which possess strong acidity and chemical stability, are promising solid proton conductors and potential candidates for proton exchange membrane fuel cell applications. To ...investigate how factors such as proton concentration and carrier affect the overall proton conduction, we have synthesized new compounds HImMo132 (Im, imidazole), HMeImMo132, ILMo132, and TBAMo132 with hollow structures and HImPMo12 with a solid spherelike structure. These crystal models were prepared by encapsulating POM with organic molecules with different proton contents. Among them, the single-crystal sample of the hollow structure HImMo132 containing more proton sources shows a high proton conductivity of 4.98 × 10–2 S cm–1, which was approximately 1 order of magnitude greater than that of the solid cluster HImPMo12 with the same proton sources and 3 orders of magnitude greater than that of the proton-free organic cation-encapsulated giant ball TBAMo132. This study provides a theoretical guidance toward designing and developing new-generation proton conductors and studying their performances at the molecular level.
The selective oxidation of C-H bonds of benzylic compounds to synthesize high-value-added ketones remains a challenge under mild conditions, and the ambiguity of its oxidation mechanism limits the ...further development of this field. In this work, we construct a polyoxometalate-based metal-organic framework (POMOF), Cu
I
2
Cu
II
(bix)
2
{V
4
O
12
} (
1
, bix = 1,4-bis(imidazole-1-ylmethyl)benzene), successfully achieving the efficient oxidation catalysis of various benzylic compounds with outstanding conversion, selectivity and durability under mild conditions. Our experimental studies suggest that the highly catalytic activity of
1
derives from its attractive structure with multiple active sites, which consists of V
V
centers in a unique U-type {V
4
O
12
}
4−
({V
4
}) cluster and Cu
I
and Cu
II
centers bridged to the {V
4
} cluster. Importantly, further theoretical calculations indicate that there exists synergistic catalysis between Cu
I
/{V
4
} sites and Cu
II
/{V
4
} sites for
1
as catalyst in the oxidation of benzylic compounds, where the {V
4
} cluster mainly provides deprotonation and oxidation sites, and the Cu
I
site plays a role in the reduction of the oxidant, while the Cu
II
site plays a role in the adsorption of the oxidant. This is the first POMOF whose catalytic mechanism towards the oxidation of benzylic C-H bonds is deeply studied through the combination of experiments and theoretical calculations, providing a new perspective for the design of related catalysts.
Multi-active site synergy in a polyoxovanadate-based mixed-valence copper metal-organic framework for efficient catalysis of C-H bond oxidation of benzylic compounds.
The design and fabrication of electrocatalysts for HER, with superior activity and stability, still remain a significant challenge for clean and renewable energy technologies. Here we have ...synthesized Fe 3 C/Mo 2 C-containing N, P co-doped graphitic carbon derived from POM@MOF-100 (Fe) (denoted as Fe 3 C/Mo 2 C@NPGC) via a “killing three birds with one stone” strategy. The Fe 3 C/Mo 2 C@NPGC catalyst demonstrates excellent electrocatalytic activity and stability towards HER with a low onset overpotential of 18 mV ( vs. RHE), small Tafel slope of 45.2 mV dec −1 , as well as long-term durability for 10 h, which is one of the best non-noble metal HER catalysts in acidic media reported so far. Most importantly, this work opens up exciting opportunities for fabricating novel and highly efficient electrocatalysts to replace Pt or Pt-based catalysts utilizing POM-based metal–organic frameworks (MOFs) as precursors.
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