Ionic metal-organic frameworks (MOFs) are a subclass of porous materials that have the ability to incorporate different charged species in confined nanospace by ion-exchange. To date, however, very few examples combining mesoporosity and water stability have been realized in ionic MOF chemistry. Herein, we report the rational design and synthesis of a water-stable anionic mesoporous MOF based on uranium and featuring tbo-type topology. The resulting tbo MOF exhibits exceptionally large open cavities (3.9 nm) exceeding those of all known anionic MOFs. By supercritical CO2 activation, a record-high Brunauer-Emmett-Teller (BET) surface area (2100 m(2)  g(-1) ) for actinide-based MOFs has been obtained. Most importantly, however, this new uranium-based MOF is water-stable and able to absorb positively charged ions selectively over negatively charged ones, enabling the efficient separation of organic dyes and biomolecules.

Ionic metal-organic frameworks (MOFs) are asubclass of porous materials that have the ability to incorporate different charged species in confined nanospace by ionexchange.T od ate,h owever,v ery few examples combining mesoporosity and water stability have been realized in ionic MOF chemistry.H erein, we report the rational design and synthesis of awater-stable anionic mesoporous MOF based on uranium and featuring tbo-type topology.T he resulting tbo MOF exhibits exceptionally large open cavities (3.9 nm) exceeding those of all knowna nionic MOFs.B ys upercritical CO 2 activation, arecord-high Brunauer-Emmett-Teller (BET) surface area (2100 m 2 g À1 )f or actinide-based MOFs has been obtained. Most importantly,however,this new uranium-based MOF is water-stable and able to absorb positively charged ions selectively over negatively charged ones,e nabling the efficient separation of organic dyes and biomolecules.

A class of metal-organic frameworks (MOFs)-namely CD-MOFs-obtained from natural products has been grown in an epitaxial fashion as films on the surfaces of glass substrates, which are modified with self-assembled monolayers (SAMs) of γ-cyclodextrin (γ-CD) molecules. The SAMs are created by host-guest complexation of γ-CD molecules with surface-functionalized pyrene units. The CD-MOF films have continuous polycrystalline morphology with a structurally out-of-plane ( c-axial) orientation, covering an area of several square millimeters, with a thickness of ∼2 μm. Furthermore, this versatile host-guest strategy has been applied successfully in the growth of CD-MOFs as the shell on the curved surface of microparticles as well as in the integration of CD-MOF films into electrochemical devices for sensing carbon dioxide. In striking contrast to the control devices prepared from CD-MOF crystalline powders, these CD-MOF film-based devices display an enhancement in proton conductance of up to 300-fold. In addition, the CD-MOF film-based device exhibits more rapid and highly reversible CO-sensing cycles under ambient conditions, with a 50-fold decrease in conductivity upon exposure to CO for 3 s which is recovered within 10 s upon re-exposure to air.

Molecules capable of performing highly efficient energy transfer and ultrafast photoinduced electron transfer in well-defined multichromophoric structures are indispensable to the development of artificial photofunctional systems. Herein, we report on the synthesis, characterization, and photophysical properties of a rationally designed multichromophoric tetracationic cyclophane, DAPPBox, containing a diazaperopyrenium (DAPP) unit and an extended viologen (ExBIPY) unit, which are linked together by two p-xylylene bridges. Both H NMR spectroscopy and single-crystal X-ray diffraction analysis confirm the formation of an asymmetric, rigid, box-like cyclophane, DAPPBox. The solid-state superstructure of this cyclophane reveals a herringbone-type packing motif, leading to two types of π···π interactions: (i) between the ExBIPY unit and the DAPP unit (π···π distance of 3.7 Å) in the adjacent parallel cyclophane, as well as (ii) between the ExBIPY unit (π···π distance of 3.2 Å) and phenylene ring in the closest orthogonal cyclophane. Moreover, the solution-phase photophysical properties of this cyclophane have been investigated by both steady-state and time-resolved absorption and emission spectroscopies. Upon photoexcitation of DAPPBox at 330 nm, rapid and quantitative intramolecular energy transfer occurs from the ExBIPY unit to the DAPP unit in 0.5 ps to yield DAPP. The same excitation wavelength simultaneously populates a higher excited state of DAPP which then undergoes ultrafast intramolecular electron transfer from DAPP to ExBIPY to yield the DAPP-ExBIPY radical ion pair in τ = 1.5 ps. Selective excitation of DAPP at 505 nm populates a lower excited state where electron transfer is kinetically unfavorable.

An octacationic diazaperopyrenium (DAPP)-based homo[2]catenane (DAPPHC), wherein no fewer than eight positive charges are associated within a mechanically interlocked molecule, has been produced in 30% yield under ambient conditions as a result of favorable homophilic interactions, reflecting a delicate balance between strong π-π interactions and the destabilizing penalty arising from Coulombic repulsions between DAPP units. This DAPPHC catenane is composed of two identical mechanically interlocked tetracationic cyclophanes, namely DAPPBox, each of which contains one DAPP unit and one extended viologen (ExBIPY) unit, linked together by two p-xylylene bridges. The solid-state structure of the homo[2]catenane demonstrates how homophilic interactions play an important role in the formation of DAPPHC, in which the mean ring planes of the two DAPPBox cyclophanes are oriented at about 60° with respect to each other, with a centroid-to-centroid separation of 3.7 Å between the mean planes of the outer ExBIPY and inner DAPP units, and 3.6 Å between the mean planes of the two inner DAPP units. We show that irradiation of the DAPPHC catenane at 330 nm in acetonitrile solution results in simultaneous energy and electron transfer. The latter occurs from the inner DAPP dimer to the outer ExBIPY unit, leading to the generation of a temporary charge-separated state within a rigid and robust homo[2]catenane. Compared to DAPPBox, both forward- and back-electron transfer in DAPPHC occur with faster rates, owing to the closer proximity between the electron donor and acceptor in the homo[2]catenane than in the separated cyclophane.

The transformation of iminyl radical into primary amine is a challenge work. Practical and green catalytic system to trigger difluoromethyl radical is highly desired. Herein, we developed a metal-free photocatalytic...

With the third technological revolution, the invention and use of electronic computers has completely pushed human development to a new stage. the arrival of the post-2020 epidemic has accelerated the pace of digital transformation, and the digital economy has become the third largest industry after agriculture and industry, becoming the new engine of national economic development. The rise of digital economy also forces the transformation and upgrading of enterprises. This paper takes the main financial indicators of listed companies in digital economy as samples and considers DEA-malmquist index in addition to traditional CCR and BCC models to discuss the linear relationship between corporate R&D inputs and revenues. The study data are more significant and can clearly illustrate the positive linear relationship between R&D investment and revenue. It is an important reference for future strategic decisions and financial expenditure allocation of economic digital companies.