Cascade Performance of Nitroarenes with Alcohols Boosted by a Hollow Flying Saucer-Shaped Ni-Al2O3 Catalyst via a MOF-Templated Strategy Induced by the Kirkendall Effect.

Catalysts with an open hollow structure can enhance the mass transfer capability of the catalyst during the reaction process, thereby further improving the catalytic performance. In this work, uniform and monodisperse flying-squircher-shaped Al-MOFs were synthesized via a solvothermal method. Furthermore, a hollow structure Al2O3-supported metallic Ni catalyst (termed Ni-Al2O3-HFA) was synthesized via the Kirkendall effect for the hydrogenation-alkylation cascade reaction by employing as-synthesized Al-MOFs as a carrier for impregnation of Ni(NO3)2·6H2O through further calcination and reduction. Various characterizations (e.g., XRD, HADDF-STEM, H2-TPR) were conducted to reveal the superior performance of the developed Ni-Al2O3-HFA catalyst compared to Ni/Al2O3-IWI (Al2O3 obtained from calcination of Al-MOFs) in cascade reaction between nitroarenes and alcohols. We hope to use the MOF template method via the Kirkendall effect to prepare hollow structure nanocatalysts, which can provide a guideline for the preparation of other hollow materials.

Mechanistic Insights into a Co(II)-Coordinated "Free" Metal Site of 2D Zinc-Based MOFs for ß-Alkylation of Secondary Alcohols with Primary Alcohols.

Through in-depth study of the properties and reaction mechanisms of catalysts, it is possible to better optimize catalytic systems and improve reaction efficiency and selectivity. This remains one of the challenges in the field of catalysis. Therefore, the research and design of catalysts play crucial roles in understanding and optimizing catalytic reaction mechanisms. A robust 2D zinc-based MOFs (Zn-HA) supported Co(II) ion catalyst (Zn-HA@Co) has been designed and synthesized via a coordination-assisted strategy for ß-alkylation of secondary alcohols with primary alcohols. The characterization demonstrated that the anchoring of Co(II) on Zn-HA via coordination could efficiently enhance the Co(II) ion dispersity and interaction between Co(II) and Zn-HA MOFs. Importantly, the density functional theory results have provided mechanistic insights into the energy of the HOMO and LUMO of the Zn-HA@Co catalyst as well as the energy change of the entire process after interacting with the reactants and the specific energy changes of each orbital. The synthesized Zn-HA@Co MOFs effectively lower the energy barrier of the catalytic reaction process. We expect that our research and design of catalysts will serve as valuable guideline for understanding and optimizing catalytic reaction mechanisms.

Lanthanide Polyoxometalate Based Water-Jet Film with Reversible Luminescent Switching for Rewritable Security Printing.

Luminescent security printing is of particular importance in the information era. However, the use of conventional paper still carries a lot of economic and environmental issues. Therefore, developing new environmentally friendly security printing material with a low cost is imperative. To achieve the aforementioned goals, novel lanthanide polyoxometalate doped gelatin/glycerol films with high transparency, high strength, and good flexibility have been developed via a solution-casting method. The electrostatic interaction between zwitterionic gelatin and polyoxometalate was confirmed by attenuated total reflection Fourier transform infrared spectroscopy. Luminescent spectra and digital images indicated that the films exhibited reversible luminescent switching properties through association and dissociation of hydrogen bonds between glycerol and water molecules, allowing its potential application as water-jet rewritable paper for luminescent security printing. Furthermore, the printed information can be conveniently "erased" by heating, and the film can be reused for printing. The film exhibited excellent ability to be both rewritten and re-erased. A QR code pattern and hybrid printing were employed to improve the security of information. In addition, the rewritable films possessed excellent regeneration ability and low toxicity, as well as good stability against UV irradiation and organic solvents. The water-jet rewritable film based on lanthanide polyoxometalate for luminescent security printing, to the best of our knowledge, has not yet been reported up to date. This work provides an attractive alternative strategy on fabricating rewritable films for luminescent security printing in terms of cutting down the cost, simplifying the preparation process, and protecting the environment.

Ultrathin Porous Carbon Nitride Bundles with an Adjustable Energy Band Structure toward Simultaneous Solar Photocatalytic Water Splitting and Selective Phenylcarbinol Oxidation.

Actiniae-like carbon nitride (ACN) bundles were synthesized by the pyrolysis of an asymmetric supramolecular precursor prepared from L-arginine (L-Arg) and melamine. ACN has adjustable band gaps (2.25 eV-2.75 eV) and hollow microtubes with ultrathin pore walls, which enrich reaction sites, improve visible-light absorption and enhance charge separation. In the presence of phenylcarbinol, ACN exhibited excellent water-splitting ability (95.3 µmol h-1 ) and in the meanwhile phenylcarbinol was selectively oxidized to benzaldehyde (conversion of 90.9 %, selectivity of 99.7 %) under solar irradiation. For the concurrent reactions, 2 D isotope labeling, separation, and detection were conducted to confirm that the proton source of released hydrogen is water. The mechanism of water splitting and phenylcarbinol oxidation was also investigated.

Correction: Effect of molybdenum carbide concentration on the Ni/ZrO2 catalysts for steam-CO2 bi-reforming of methane.

[This corrects the article DOI: 10.1039/C5RA22237K.].

Structures and luminescent sensors of mixed-counterions based salen-type lanthanide coordination polymers.

Reactions of N,N'-bis (salicylidene)-1,2-cyclohexanediamine (H2 L) with mixed lanthanide counterions of LnCl3 ·6H2 O and Ln (NO3 )3 ·6H2 O afford six H2 L lanthanide coordination polymers, e.g. {[Pr(H2 L)2 (NO3 )2 Cl]·2CH2 Cl2 }n (1); {[Ln(H2 L)1.5 (NO3 )3 ]2 ·5CHCl3 ·mCH3 OH}n [Ln = Sm (2), Eu (3), Gd (4), Tb (5) and Yb (6); m = 1 (2-5); m = 0 (6)]. X-ray crystallographic analysis reveals that complex 1 exhibits three-dimensional diamondoid topologic structure and complexes 2-6 are of two-dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near-infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2-5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.

High Catalytic Performance of a CeO2-Supported Ni Catalyst for Hydrogenation of Nitroarenes, Fabricated via Coordination-Assisted Strategy.

A family of two-dimensional salen-type lanthanide complexes was synthesized through a facile solution diffusion method. The two-dimensional lanthanide complexes were characterized by single-crystal X-ray diffraction (SCXRD) and X-ray photoelectron spectroscopy (XPS) analytical techniques. The SCXRD and XPS analyses reveal that the obtained two-dimensional structures are rich in uncoordinated imine (-CH═N-) groups located on the skeleton of the salen-type organic ligand, which retain strong coordination ability with metal ions. On the basis of this unique feature, a highly dispersed CeO2-supported Ni catalyst (Ni/CeO2-CAS) with highly strong metal-support interaction was first synthesized via a coordination-assisted synthesis (CAS) method, which exhibits a much better catalytic activity in the hydrogenation of nitrobenzene than the traditional Ni/CeO2-IWI catalyst prepared by incipient wetness impregnation (IWI). The origin of the improved catalytic activity of Ni/CeO2-CAS as well as the role of Ni@Ce-H2salen was revealed by using diverse characterizations. On the basis of the comparative characterization results, the superior catalytic performance of Ni/CeO2-CAS to Ni/CeO2-IWI could have resulted from the smaller and highly dispersed Ni nanoparticulates, the intensified Ni-CeO2 interaction, the enhanced NiO reducibility, and the higher concentration of oxygen vacancies, favoring the H2 dissociation and adsorption of the nitrobenzene reactant. The Ni/CeO2-CAS catalyst also exhibits high catalytic performance for reduction of diverse nitroarenes to their corresponding functionalized arylamines. We anticipated that this coordination-assisted strategy may provide a new way for preparing other highly oxide-supported catalysts with potential applications in various catalytic reactions.

Investigation of magneto-structural correlation based on a series of seven-coordinated ß-diketone Dy(iii) single-ion magnets with C2v and C3v local symmetry.

A series of four ß-diketone mononuclear Dy(iii) complexes, namely Dy(Hthd)3(MeOH)·2,5-Py (1), Dy(Hthd)3(Tppo) (2), Dy(Hthd)3(PyNO) (3), and Dy(Hthd)3(4-PyNO) (4) (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione, 2,5-Py = 2,5-pyridine, Tppo = triphenylphosphine oxide, PyNO = pyridine N-oxide, 4-PyNO = 4-methylpyridine N-oxide), have been isolated by reactions of Hthd, DyCl3·6H2O and an auxiliary ligand. X-ray crystallographic analysis revealed that complexes 1-4 are all seven-coordinated mononuclear structures with C2v or C3v local symmetry. The magnetic measurements of complexes 1-4 revealed their field-induced single-ion magnet (SIM) behavior, due to mixed low-lying states. The crystal field parameters and orientations of the magnetic easy axes were obtained from simulations of the DC magnetic data and an electrostatic model calculation. The magneto-structural correlation of seven-coordinated Dy(iii) SIMs with low-symmetry coordination environments was further discussed.

Efficient red emission from PMMA films doped with 5,6-DTFI europium(III) complexes: synthesis, structure and photophysical properties.

A new ß-diketone, 5,6-dimethoxy-2(2,2,2-trifluoroethyl)-1-indone (5,6-DTFI), has been designed and synthesized. Two series of four 5,6-DTFI Sm(3+) and Eu(3+) complexes, namely, Eu(5,6-DTFI)3(H2O)2 (1), Eu(5,6-DTFI)3(Phen) (2), Sm(5,6-DTFI)3(H2O)2 (3) and Sm(5,6-DTFI)3(Phen) (4) (Phen = 1,10-phenanthroline), have been isolated. X-ray diffraction analysis reveals that all complexes 1-4 are of mononuclear structures. Luminescent and phosphorescent spectra of complexes 1-4 show strong characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions. Upon complexes 1 and 2 were doped into the poly(methylmethacrylate) (PMMA) forming the films, the PMMA polymer matrix acting as a co-sensitizer for Eu(3+) ion enhances the luminescent lifetimes, overall quantum yields and the thermal stability in comparison with the precursor complexes.