No abstract

Metal clusters exhibit diverse structures, emerging functions, and applications; thus, incorporating clusters into metal-organic frameworks (MOFs) brings tremendous merits. Although the construction of cluster-based MOFs is sophisticated, the reticular materials constructed from a combination of the chemistry of metal clusters and covalent organic frameworks (COFs) remain unexplored. Herein, we prepared two Cu(I) cluster-based MOFs with cyclic trinuclear units (CTUs), termed JNM-1 and JNM-2, either by a stepwise synthetic approach or by a one-pot reaction, for networking clusters with dynamic covalent chemistry, rarely utilized in MOF synthesis. The generated JNMs exhibited excellent stability and could be used as recyclable catalysts for palladium-free Sonogashira coupling reactions with high efficiency and tolerance (>90% yield for nine examples), without loss of performance for at least five cycle runs. In addition, conjugated single molecular wires with lengths ranging from 1.6 to 2.7 nm were synthesized feasibly using the JNM-1 catalyst.

Tungsten-based polyoxometalates( POMs) have been employeda sU V-driven photo-catalysts for ar ange of organic transformations. Their photoactivityi sd ependent on electronic transitionsb etween frontier orbitals and thus manipulation of orbital energy levels provides ap romising meanso fe xtending their utility into the visible regime. Herein, an organic-inorganic hybrid polyoxometalate, K 6 [P 2 W 17 O 57 (PO 5 H 5 C 7 ) 2 ]·6C 4 H 9 NO, was foundt o exhibite nhanced redox behaviour andp hotochemistry compared to its purely inorganicc ounterparts. Hybridization with electron-withdrawingm oieties was shownt o tune the frontier orbitale nergy levels and reduce the HOMO-LUMO gap, leading to direct visible-lightp hotoactivationof the hybrid and establishing as imple, cheap and effective approacht ot he generation of visible-lightactivated hybrid nanomaterials.Systemst hat harness energy from visible light are among the most prized targets in modern materials design.[1] Ap romising group of photoactive materials, polyoxometalates (POMs), are discrete early transition-metal-oxide clusters that exhibite xcellent stability,s olubility in both aqueous and organic mediaa nd aw ide range of potentialc ompositions and structures.[2] These nanoscopic clusters are characterized in large part by their rich redox chemistry,l eadingt op otentiala pplicationsi nm ulti-electron transfer and charge-storaget echnologies.[3] Most importantly,t heir capacity to form highly active photo-excited states (oxo-centred radicals) upon excitation of the O!Ml igand-tometal charge transfer (LMCT) band [4] has led to sustainedi nterest in their use as both heterogeneous and homogeneous photocatalysts for ar ange of transformations.[5] In particular, tungstate-based POMs have been successfully employed in ar ange of UV-light-driven photooxidationr eactions. [4a, 6] In their native state, POMs typically exhibit negligible visible light absorption, with the broad LMCT band located almostentirely within in the UV region of the spectrum.P OMs have thus had limited application in visible-light-driven catalysis and while the absorption profiles of molybdate-and vanadatebased POMs often tail into the near-visible/blue range, [4, 7] they do not generally exhibit the stability or easeo ff unctionalization seen in tungstate-baseda nalogues.Mizuno and co-workersr ecently reported two examples of polyoxotungstate photoactivation in systemsb ased on the lacunary POM [g-SiW 10 O 36 ] 8À ,i nw hich charget ransferf rom secondary components (Ce III or bound substrates) facilitated photo-reduction of the POMcorea nd allowedo xidative catalysis on the appended moieties.[8] Another approach to the visible-lighta ctivation of POMs is through functionalization with (typically, preciousm etal-based) visible-light-activec hromophores or 'photosensitizers' (PS), throughe ither supramolecular or covalenta pproaches.[9] Subsequentp hoto-excitation can lead to PS!POMc harge transfer.[10] Indeed, to the best of our knowledge,a ll previous reports of polyoxot...

Luminescence piezochromism have risen to prominence in recent decades, while most are limited in pure organic compound and fluorescence. In this work, a Cu3Pz3 (Cu3, Pz: pyrazolate) cyclic trinuclear complex...

Two-dimensional (2D) metal–organic framework nanosheets (MONs) or membranes are classes of periodic, crystalline polymeric materials that may show unprecedented physicochemical properties due to their modular structures, high surface areas, and high aspect ratios. Yet preparing 2D MONs from multiple components and two different types of polymerization reaction remains challenging and less explored. Here, we report the synthesis of MOF films via interfacial polymerization, which involves three active monomers for simultaneous polycondensation and polycoordination taking place in a confined interface. The well-defined lamellar structure of the MOF films allowed feasible and scalable exfoliation to produce free-standing 2D MONs with high aspect ratio up to 2000:1 and ultrathin thickness (∼1.7 nm). The pore structure was revealed by high-resolution TEM images with near-atomic precision. The imide-linkage of MONs provided superior thermal (up to 530 °C) and good chemical stability in the pH range from 3 to 12. More importantly, the MONs exhibited exceptional catalytic activity and superior reusability for the hydroboration reactions of alkynes, in which the turnover frequency (TOF) reached 41734 h–1, which is 2–4 orders of magnitude greater than that reported for homogeneous and heterogeneous catalysts.