A convenient synthesis of highly luminescent lanthanide 1D-zigzag coordination chains based only on 4,4′-bipyridine as connector

The coordination polymers View the MathML source·C7H8 (Ln = Eu, β-dik = dbm, tta, hfac; Ln = Tb; β-dik = dbm; Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac: hexafluoroacetylacetone) were easily assembled in mild conditions and high yields starting from the anhydrous lanthanide β-diketonates as nodes and 4,4′-bipyridine (bpy) as connector. X-ray single crystal studies have shown zigzag extended chains where lanthanide centres are 8-coordinated in a distorted square-antiprismatic geometry. Photoluminescence studies show bright red europium emission and spectral features dependent on the topology of the polymeric chains

Copper single-atoms embedded in 2D graphitic carbon nitride for the CO2 reduction

AbstractWe report the study of two-dimensional graphitic carbon nitride (GCN) functionalized with copper single atoms as a catalyst for the reduction of CO2 (CO2RR). The correct GCN structure, as well as the adsorption sites and the coordination of the Cu atoms, was carefully determined by combining experimental techniques, such as X-ray diffraction, transmission electron microscopy, X-ray absorption, and X-ray photoemission spectroscopy, with DFT theoretical calculations. The CO2RR products in KHCO3 and phosphate buffer solutions were determined by rotating ring disk electrode measurements and confirmed by 1H-NMR and gas chromatography. Formate was the only liquid product obtained in bicarbonate solution, whereas only hydrogen was obtained in phosphate solution. Finally, we demonstrated that GCN is a promising substrate able to stabilize metal atoms, since the characterization of the Cu-GCN system after the electrochemical work did not show the aggregation of the copper atoms

A film-forming graphene/diketopyrrolopyrrole covalent hybrid with far-red optical features: Evidence of photo-stability

A dianiline derivative of a symmetric donor-acceptor-donor diketopyrrolopyrrole-based dye is employed for the two-sided covalent functionalization of liquid exfoliated few layers graphene flakes, through a direct arylation reaction. The resulting nanohybrid features the properties of a polymeric species, being solution-processed into homogeneous thin films, featuring a pronounced red-shift of the main absorption band with respect to the model dye unit and energy levels comparable to those of common diketopyrrolopyrrole-based polymers. A good electrical conductivity and the absence of radical signals generated after intense white light illumination, as probed through electron paramagnetic resonance, suggest a possible future application of this composite material in the field of photoprotective, antistatic layers with tunable colors

Electronic and relating behavior of Mn-doped ZnO nanostructures: An x-ray absorption spectroscopy study

Controlled synthesis of Mn-doped ZnO nanostructures with Mn concentrations of 1%, 3%, and 10% at. has been carried out using sol\u2013gel methods and temperature treatments at 400, 600, and 800 \u25cbC. It is found that Mn is successfully introduced into the hcp oxide lattice of ZnO nanoparticles of a range of sizes from a few nm to 102 nm, depending on temperature conditions. It is also found that a secondary phase appears as the Mn concentration and processing temperature increase, most probably in the form appropriately described as MnOx clusters on the surface, although the dominant component remains hcp ZnO. The x-ray absorption near edge structure at all edges of interest reveals that the Mn2+ ion substitutes Zn2+ at the tetrahedral site and that the secondary phase exhibits a clear signature of the octahedral local environment at the Mn L3,2 and O K-edge. X-ray excited optical luminescence excited at 1085 eV (just above the Zn L3,2 edge) shows that the characteristic bandgap emission is slightly blue shifted and the luminescence from both the bandgap and defect emission is quenched somewhat with the latter significantly shifted to longer wavelengths in the region observed for surface and near surface defects. The Mn- doped samples processed at low temperature are poor light emitters due to the high degree of disorder and improve markedly with annealing at higher temperature. The magnetic properties of these systems were also investigated. The results suggest that Mn doping impedes radiative recombination, which is in favor of improved photocatalytic behavior. The implication of these findings is discussed