A Stable 3d-4f Heterometallic Cluster with Magneto-Optical Activity.

A stable 3d-4f heterometallic cluster, namely, {Dy4Ni5L10(NO3)4(CO3)4(CH3OH)2}·CH3CN (Dy4Ni5, HL = 8-hydroxyquinoline), has been solvothermally synthesized and structurally characterized. The compound exhibits an interesting structure in which a tetrahedron based on 4f ions interpenetrates with a square pyramid based on 3d ions. Besides, a unique intermolecular interaction was found in Dy4Ni5, giving rise to its high stability not only when it is in the solid state but also when it dissolves in organic solvents. In addition, the magnetic behavior of solid Dy4Ni5 and the magneto-optical activity of the Dy4Ni5 solution were also studied.

Static Retention of Dynamic Chiral Arrangements for Achiral Shear Thinning Metal-Organic Colloids.

Chiral compounds are known to be important not only because they are the fundamental components of living organisms, but also for their unique chiroptical properties. In recent years, scientists have fabricated several chiral organic supramolecular aggregates by using chiral physical fields, such as vortex flow. Herein, the relationship between dynamic chiroptical properties and rheological nature is discussed, suggesting the shear thinning properties of non-Newtonian fluids might help colloidal particles adopt a chiral arrangement in vortices. Furthermore, the storage modulus of colloids could be increased by adding a linking agent, which successfully kept the dynamic chiroptical properties in the static state. Moreover, the salt effect on the host-guest interaction involved in the colloids was studied, the results suggested a significant enhancement of the transferred dynamic circular dichroism for the achiral guest molecule.

One-step oxidation preparation of unfolded and good soluble graphene nanoribbons by longitudinal unzipping of carbon nanotubes.

A simple one-step method to prepare graphene nanoribbon (GNR) is reported in this paper. Compared with water steam etching, the oxidation and co-etching of dilute sulfuric acid can result in the more complete longitudinal unzipping of carbon nanotube, although there is no other strong oxidant. As-prepared GNRs are more flat and have more oxygenated functional groups along the edge. Moreover, they can steadily disperse in a water system. These make them suitable as a carrier for supporting palladium (Pd) nanoparticles. The Pd/GNR composite exhibits a superior electrocatalytic activity for ethanol oxidation.

Growth, Faraday and inverse Faraday characteristics of Tb2Ti2O7 crystal.

Tb2Ti2O7 (TTO) single crystal with dimensions of 20 × 20 × 16 mm3 was grown by the Czochralski method. Rietveld structure refinement of X-ray diffraction (XRD) data confirms that the compound crystallizes in the cubic system with pyrochlore structure. Transmission spectra, Magnetic circular dichroism (MCD) spectra, Faraday and inverse Faraday characteristics of TTO crystal have been measured and analyzed in detail. The results demonstrate that TTO crystal has high transmittance at 700-1400 nm waveband and a larger Verdat constant than that of TGG reported. Magnetic circular dichroism (MCD) spectra showed that the 4f→4f transitions of Tb3+ have significant contributions to the magneto-optical activity (MOA). In the time-resolved pump-probe spectroscopy, the rotation signals of the probe beam based on the inverse Faraday effect in magneto-optical crystal were observed at zero time delay, the full width at half maximum of the rotation and ellipticity signals can be as fast as ~500 fs, which indicates that TTO crystal can be a promising material for ultrafast all-optical magnetic switching.

Enantioselective synthesis of a chiral coordination polymer with circularly polarized visible laser.

Circular dichroism is known to be the feature of a chiral agent which has inspired scientist to study the interesting phenomena of circularly polarized light (CPL) modulated molecular chirality. Although several organic molecules or assemblies have been found to be CPL-responsive, the influence of CPL on the assembly of chiral coordination compounds remains unknown. Herein, a chiral coordination polymer, which is constructed from achiral agents, was used to study the CPL-induced enantioselective synthesis. By irradiation with either left-handed or right-handed CPL during the reaction and crystallization, enantiomeric excesses of the crystalline product were obtained. Left-handed CPL resulted in crystals with a left-handed helical structure, and right-handed CPL led to crystals with a right-handed helical structure. It is exciting that the absolute asymmetric synthesis of a chiral coordination polymer could be enantioselective when using CPL, and provides a strategy for the control of the chirality of chiral coordination polymers.

Clean unzipping by steam etching to synthesize graphene nanoribbons.

A simple, clean method of steam etching carbon nanotubes is reported for the synthesis of graphene nanoribbons. The chemical mechanism of carbon nanotube unzipping is also discussed. As an anode catalyst, as-prepared graphene nanoribbons combined with Pt exhibit quite a high catalytic activity for ethanol electro-oxidation in fuel cells.

High efficiency and stable photoluminescence of CH3NH3PbBr3@CsPbBr3 perovskite quantum dots.

CH3NH3PbBr3@CsPbBr3 quantum dots were prepared by epitaxially growing a CsPbBr3 shell on the surface of CH3NH3PbBr3 due to their similar crystal structures. The inorganic CsPbBr3 shell provides enhanced stability for the CH3NH3PbBr3 core. Compared with that of CH3NH3PbBr3, the photoluminescence of CH3NH3PbBr3@CsPbBr3 quantum dots is not only strong, but also stable for months, in addition to having a high quantum yield.

Growth, structure and defects of (La,Sr)(Al,Ta)O3 crystals for preparing BiFeO3 thin films.

A new (La,Sr)(Al,Ta)O3 (LSAT) crystal is focused on in this paper to be used as an ideal substrate for preparing perfect BiFeO3 thin films. The crystal structures are designed with a low lattice mismatch between LSAT and BiFeO3. LSAT crystals were grown by the Czochralski method. In order to get colourless crystals with high transmittance, density functional theory is used to simulate the crystals with different defects. From the results, it is found that the colour centre originates from the defect of VSr + VO or VSr + 2VO. Thus, it is necessary for the crystals to be annealed in O2 and then in N2. High-quality BiFeO3/LSAT thin films will have promising application prospects.

Influence of choice of substrate and film thickness on magneto-optical properties of SmFeO3 thin films.

Herein, SmFeO3 thin films are prepared by using magnetron sputtering technology on quartz-glass and SrTiO3(STO)(1 0 0) substrates. The influence of film thickness and choice of substrate on film quality and growth orientation is studied in detail. Moreover, the impact of phase purity and growth orientation on optical, magnetic and magneto-optical properties is discussed. The results reveal that the film thickness and choice of substrate significantly influence the induced stresses at film/substrate interface and growth orientation of the annealed film. The as-fabricated SmFeO3 thin films have demonstrated highly crystalline structure, excellent transmittance and enhanced magneto-optical properties. Moreover, obvious anisotropy in magnetization and magneto-optical properties has been observed. The SmFeO3 films with excellent magneto-optical properties can be fabricated by selecting optimal film thickness and substrate. It is expected that SmFeO3 film is a promising material for integrated optical isolators and magneto-optical modulators.

Structural design of cubic Sr,V:CeFeO3 thin films with a strong magneto-optical effect and high compatibility with a Si substrate.

This paper focuses on strong magneto-optical thin films that closely match a Si substrate. The orthorhombic perovskite crystal structure of CeFeO3 was optimized to a cubic perovskite structure by introducing strontium and vanadium ions into lattice. The cubic Ce1-xSrxFe1-xVxO3 (x = 0.3, 0.5, 0.7) thin films with high quality and high growth orientation were prepared on a Si substrate by using the RF magnetron sputtering method. Moreover, the birefringence effect, which may weaken the magneto-optical effect, should not occur in the cubic thin film. The calculation results based on density functional theory show that the increased electronic transition probability is attributed to the strong spin-coupling between the hybrid Ce3+ 4f and Fe3+/V4+ 3d states. The magnetic circular dichroism ellipticity |ΨF| of the Ce0.7Sr0.3Fe0.7V0.3O3 thin film is up to 4300 deg. cm-1, which indicates a strong magneto-optical effect. Therefore, the cubic Ce1-xSrxFe1-xVxO3/Si film with high Ce3+ concentration is expected to be a new candidate for integrated magneto-optical devices.

A series of pure-blue-light emitting Cu(i) complexes with thermally activated delayed fluorescence: structural, photophysical, and computational studies.

Four mononuclear Cu(i)-halide complexes containing phosphines and pyridine ligands with strong electron donor substituents, [CuCl(PPh3)2(4-NMe2py)] (1), [CuI(PPh3)2(4-NH2py)] (2), [CuI(POP)(4-NH2py)] (3), and [CuI(POP)(4-NMe2py)]·0.5(Et2O) (4), (PPh3 = triphenylphosphine, 4-NMe2py = 4-(dimethylamino)pyridine, POP = bis[(2-diphenyl-phosphino)phenyl]ether, 4-NH2py = 4-aminopyridine, Et2O = diethyl ether) were synthesized and studied with regard to their structural, photophysical properties and theoretical calculations. The complexes exhibit pure blue thermally activated delayed fluorescence (λmax = 442 (1), 436 (2), 464 (3), and 448 nm (4)) in crystalline at room temperature. Emission lifetime analyses and density functional theory (DFT) calculations show that the blue-light emission at room temperature is the singlet (metal + halide)-to-ligand charge transfer state, (1(M + X)LCT), while that at 77 K is the state of 3(M + X)LCT transition character, owing to the small singlet-triplet energy gaps (ΔE = 660-1680 cm-1). X-ray diffraction structure analysis, photophysical studies and theoretical calculations suggest that the much larger torsion angle between the N-heterocyclic rings and N-Cu-X planes of complex 3 than that of 1, 2 and 4 might causes the bathochromic shift of luminescence, although these complexes containing similar heterocycle ligands.