RESUMO
Two isoreticular metal-organic frameworks (MOFs) constructed from M8(OH)4(H2O)2(pyz)12 (M = Co, Ni; pyz = pyrazolate) secondary building units (SBUs) and Ni(salen)-derived metalloligands were synthesized. The two MOFs were found to be highly stable in a wide pH and temperature range. Together with the tetrabutylammonium bromide (TBAB) co-catalyst, they catalysed the cycloaddition of CO2 to epoxides with near-quantitative yields and easy recyclability for at least 11 cycles.
RESUMO
A metal-organic framework (MOF) built from a combination of metal cations, neutral azole ligands and sulphate anions, [Cu2(DHBDI)3(SO4)2]n (1, DHBDI = 1H,5H-benzo[1,2-d:4,5-d']diimidazole), was synthesized. MOF 1 exhibits good chemical stability in acids, bases and boiling water while showing high hydrophilicity. Meanwhile, MOF 1 exhibits a proton conductivity of 1.14 × 10-3 S cm-1 at 90 °C and 98% RH, among the best for MOF materials with uncoordinated N sites. Temperature-dependent conductivity measurements suggest a vehicle mechanism (Ea = 0.64 eV) for proton transport.
RESUMO
The catalytic acceptorless dehydrogenation (CAD) is an attractive synthetic route to unsaturated compounds because of its high atomic efficiency. Here we report electrochemical acceptorless dehydrogenation of N-heterocycles to obtain quinoline or indole derivatives using metal-organic layer (MOL) catalyst. MOL is the two-dimensional version of metal-organic frameworks (MOF), and it can be constructed on conductive multi-walled carbon nanotubes via facile solvothermal synthesis to overcome the conductivity constraint for MOFs in electrocatalysis. TEMPO-OPO3 2- was incorporated into the system through a ligand exchange with capping formate on the MOL surface to serve as the active catalytic centers. The hybrid catalyst is efficient in the organic conversion and can be readily recycled and reused.
RESUMO
Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4â¡: <Δ2â¡>Δ<Δ2â¡>). Solid solutions of PbTb1-xEuxB7O13 (x = 0-1) were prepared via a solid state reaction and the photoluminescence properties were studied. The results show that under UV or near-UV excitation, the luminescence colour of samples of PbTb1-xEuxB7O13 (x = 0-1) can be tuned from green through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentrations, because of the Tb3+ â Eu3+ energy transfer mechanism.
RESUMO
A series of orthophosphates Na3Ln(PO4)2 (Ln = lanthanoids) have for a long time been known as good luminescent materials, yet their crystal structures have not been studied in full detail. In this work, compound Na3La(PO4)2 was prepared using molten salt (flux) method and for the first time was structurally determined on X-ray single-crystal diffraction data. Interestingly, it crystallizes in the four-dimensional incommensurately modulated structure with orthorhombic superspace group Pca21(0ß0)000 and modulation wave vector q = 0.387b*. Furthermore, to evaluate the potentiality of Na3La(PO4)2 to be used as a luminescent host material, 5 mol % Eu3+, Tb3+, and Dy3+ doped phosphors were prepared, respectively. The excitation spectra, emission spectra, decay time, quantum efficiency, and the color purity of prepared phosphors, Na3La0.95Eu0.05(PO4)2, Na3La0.95Tb0.05(PO4)2, and Na3La0.95Dy0.05(PO4)2, were studied.