A series of remarkable crystalline compounds [Cu(2)(BTC)(4/3)(H(2)O)(2)](6)[H(n)XM(12)O(40)].(C(4)H(12)N)(2) (X = Si, Ge, P, As; M = W, Mo) were obtained from the simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate (BTC), and different Keggin polyoxometalates (POMs). In these compounds, the catalytically active Keggin polyanions were alternately arrayed as noncoordinating guests in the cuboctahedral cages of a Cu-BTC-based metal-organic framework (MOF) host matrix. X-ray crystallographic analyses, TG, FT-IR, UV-vis, N(2) adsorption studies, and acid-base titration demonstrated their high stability and toleration for thermal and acid-base conditions. No POM leaching or framework decomposition was observed in our study. The representative acid catalytic performance of a compound containing PW(12) species was assessed through the hydrolysis of esters in excess water, which showed high catalytic activity and can be used repeatedly without activity loss. Moreover, catalytic selectivity, which is dependent on the molecular size of substrates, and substrate accessibility for the pore surface were observed. It is the first time that the well-defined, crystalline, MOF-supported POM compound has behaved as a true heterogeneous acid catalyst. The unique attributes of MOF and well-dispersed level of POMs prohibited the conglomeration and deactivation of POMs, which allowed for the enhancement of their catalytic properties.

Polyoxometalate (POM)-based metal-organic framework (MOF) materials contain POM units and generally generate MOF materials with open networks. POM-based MOF materials, which utilize the advantages of both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades. They have good prospects in catalysis owing to the electronic and physical properties of POMs that are tunable by varying constituent elements. In this review, we present recent developments in porous POM-based MOF materials, including their classification, synthesis strategies, and applications, especially in the field of catalysis.

A series of all-inorganic, abundant-metal-based, high-nuclearity cobalt-phosphate (Co-Pi) molecular catalysts [{Co4(OH)3(PO4)}4(SiW9O34)4](32-) (1), [{Co4(OH)3(PO4)}4(GeW9O34)4](32-) (2), [{Co4(OH)3(PO4)}4(PW9O34)4](28-) (3), and [{Co4(OH)3(PO4)}4(AsW9O34)4](28-) (4) were synthesized and shown to be highly effective at photocatalytic water oxidation. The {Co16(PO4)4} cluster contains a Co4O4 cubane which is structurally analogous to the [Mn3CaO4] core of the oxygen-evolving complex (OEC) in photosystem II (PSII). Compounds 1-4 were shown to be the first POM-based Co-Pi-cluster molecular catalysts for visible light-driven water oxidation, thus serving as a functional model of the OEC in PSII. The systematic synthesis of four isostructural analogues allowed for investigating the influence of different heteroatoms in the POM ligands on the photocatalytic activities of these Co-Pi cluster WOCs. Further, the POM-based photocatalysts readily recrystallized from the photocatalytic reaction systems with the polyoxoanion structures unchanged, which together with the laser flash photolysis, dynamic light-scattering, (31)P NMR, UV-vis absorption, POM extraction, and ICP-MS analysis results collectively confirmed that compounds 1-4 maintain their structural integrity under the photocatalytic conditions. This study provides not only a valuable molecular model of the "Co-Pi" catalysts with a well-defined structure but also an unprecedented opportunity to fine-tune high-nuclearity POM clusters for visible light-driven water splitting.

Benefiting from the unique advantages of MOFs materials, efficient delivery of various kinds of drugs has been achieved in some MOF materials. However, it is only the outset of MOFs in drug delivery system, and numerous work need to be done before clinical applications, for example, studying their in vivo toxicity, exploring degradation mechanisms so as to establish real stability of MOFs in body's liquid, providing appropriated surface modification avenue for MOFs, and researching in vivo efficiency and pharmacokinetics of drug-loaded MOFs.

To rationalize the marked difference in the energy conversion efficiency of dye sensitized solar cells (DSSCs) based on organic dyes 1 and 2 different only in their p spacer, density functional theory (DFT) and time-dependent DFT calculations of the geometries, electronic structures and absorption spectra of the organic dyes before and after binding to titanium oxide were carried out. These enable us to determine factors such as dipole moments associated with the open-circuit photovoltage (V oc ), and to quantify parameters such as the light harvesting efficiency, the electron injection efficiency associated with the short-circuit photocurrent density (J sc ). The results reveal that compared to 2 with a thiazole spacer, 1 with a thiophene spacer could cause a red shift of the absorption spectrum, increase the oscillator strength and improve the driving force for electron injection, thus leading to the larger J sc , in good agreement with experimental data. As for V oc , our results stress that apart from the generally emphasized vertical dipole moment of the dyes pointing outward from the semiconductor surface, the number of photoinjected electrons from the dye to the semiconductor is also crucial to obtain high performance dyes with high V oc . After justifying the reliability of the quantum-chemical methods, we designed another four dyes with different p spacers to screen more efficient organic dyes. Fortunately, taking 1 as reference, we find that dye 4 with a thienothiophene spacer displays an enhanced J sc and V oc , indicating that it will be a more efficient diarylamine-fluorene-based organic dye used in DSSCs, which will play a theoretical guiding role in the design and synthesis of new organic dyes.

Graphitic carbon nitride (g-C3N4) can be used as a photocatalyst to reduce CO2. Doping is an efficient strategy for improving the photocatalytic activity and tuning the electronic structure of g-C3N4. The sulfur-doped g-C3N4 (S-doped g-C3N4) as a promising photocatalyst for CO2 reduction was investigated by density functional theory methods. The electronic and optical properties indicate that doping S enhances the catalytic performance of g-C3N4. From the reduction Gibbs free energies, the optimal path for CO2 reduction reaction to CH3OH production catalyzed by S-doped g-C3N4 is CO2 → COOH* → CO → HCO* → HCHO → CH3O* → CH3OH. In comparison with g-C3N4, doping S can alter the rate-determining step and reduce the Gibbs free energy from 1.43 to 1.15 eV. CO2 reduction activity of S-doped g-C3N4 is better than that of g-C3N4, which is in well agreement with the experimental results. Our work provides useful insights into designing nonmetal-doped g-C3N4 for photocatalytic CO2 reduction reactions.

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We describe here two unusual polyrotaxane-like metal-organic frameworks of [Co2(1,3-bix)2(bpea)2] and [Cd4(1,4-bix)4(bpea)4] x 4H2O , where both species contain loops and rods that are interlaced in a highly rare "parallel" fashion in , but, uniquely, in an "inclined" fashion in .