The Ca3Sc2Ge3O12:Cr3+ NIR emission garnet phosphor exhibits broadband emission peaking at 817 nm with a FWHM value of 128 nm. The developed phosphor presents balanced comprehensive performance and is suitable for NIR-LED application.

Abstract

The rapid growth in phosphor-converted near-infrared light-emission diodes (NIR-LEDs) has led to the development of NIR emitter with high efficiency, broadband emission and high thermal stability. In this work, an efficient broad NIR emission of Cr³⁺ in novel Ca₃Sc₂Ge₃O₁₂ (CSGO) garnet-based host was developed for the first time, which located at 700 to 1000 nm peaking at 817 nm with a broad bandwidth of ~128 nm. Such a broadband NIR emission originated from the preferential occupancy of Cr³⁺ in Sc³⁺ sites with weak octahedral field, which was manifested by the luminescence spectrum and decay behaviors. The Cr³⁺-doping concentration was regulated to achieve a good internal quantum efficiency (IQE) of 72.1 % and a fantastic thermal stability (at 423 K, sustained approximately 85 % of the initial intensity). The mechanism for concentration and thermal quenching was further investigated. Benefiting from the excellent luminescence features, a prototype NIR-LEDs was assembled via integrating the optimized samples with commercial blue InGaN LED chips, which exhibited a satisfactory photoelectric property and a brilliant performance in night vision. These results demonstrated the as-obtained sample to be a great potential candidate for NIR-LEDs.

Metal-containing peptide (bio-)conjugates have received continuous interest due to their enormous potential for bioinorganic and medicinal research. In many bioconjugates the chemical inertness of the metal-containing units facilitates synthesis e.g. by copper-catalyzed alkyne-azide cycloaddition or the formation of peptide bonds. However, when the metal complex contains labile ligands, which are often critical to their biological activity, the synthetic proceeding requires careful planning. Here, we report on the synthesis of a set of peptide bioconjugates with a platinum(II) core, coordinated through widely variable (O,S) chelating β-hydroxydithiocinnamic ester and two monodentate ligands. We have evaluated the synthetic applicability of metal-peptide bioconjugation techniques between the model peptide Leu5-enkephalin and differently functionalized (O,S)Pt units. Within this, the type and position of anchor used at the β-hydroxydithiocinnamic unit proved to be crucial for success, but equally important was the synthetic order of conjugation and complexation.

Metal-free cycloaddition reactions between a diazido-diborane and alkynes are used to synthesize new ditriazolyl-diborane molecules, a bis(ferrocenyl-1,2,3-triazolyl)-diborane and a bis(2-pyridyl-1,2,3-triazolyl)-diborane. Then, the bis(2-pyridyl-1,2,3-triazolyl)-diborane was used as polydentate ligand for the synthesis of larger architectures. Reaction with ditriflato-diborane yielded a tetracationic hexaboron compound, and reaction with metal salts yielded dicationic ring compounds with two hexacoordinate metal atoms and two integrated diborane units.

Transition-metal oxides (MOx) play essential roles in chemistry, catalysis, materials science and metallurgy. The MOx reduction and doping are two ubiquitous reactions in academic research and industrial manufacturing, but they are notoriously energy-demanding and require harsh conditions (high temperatures, long durations). In this work, facilitated by mechanochemical ball milling, we report a new route to conduct MOx reduction and doping at room temperature within 20 minutes enabled by mechanochemical ball milling and lithium metal.

Copper (I) based halide scintillators have received high attention due to their high light yield. At the same time, researchers are increasingly interested in exploring organic-inorganic hybrid copper(I) based halides, due to the diversity and tunability of structures. Here, we describe high-efficiency photoluminescence and X-ray excited luminescence in (DFPD)3Cu2I5 (1) (DFPD = 4,4-difluoro-bipiperidinium). 1 is comprised of a unique [Cu2I5]3− cluster, which have typical structure allowing high-transition-probability self-trapped exciton emission (one Cu+ ion adopts the tetrahedral coordination geometry, the other trigonal planar coordination geometry, the Cu−Cu distance (2.574 Å) is short). Accordingly, 1 shows efficient yellow-green photoluminescence with the maximum at 527 nm, a full-width at half-maximum of 99.2 nm, a large Stokes shift of 214 nm (1.6 eV) and a quantum yield of 77.15%. Polycrystalline 1 can also convert high-energy X-ray photons into UV-visible pulsed fluorescence with the light yield of 5000 photons/MeV. This finding plays a valuable role in the development of organic-inorganic hybrid copper(I) based scintillators.

We report the synthesis of a series of temperature-sensitive non-classical early Ln(II) (Ln = lanthanide) complexes, [K(2.2.2-cryptand)][Ln(Cptt)3] (Cptt = C5H3tBu2-1,3; 1-Ln; Ln = La-Nd). Complexes 1-Ln were typically prepared using Schlenk line techniques rather than more common glove box protocols, by the reduction of the parent Ln(III) complexes [Ln(Cptt)3] (2-Ln) with KC8 in THF in the presence of 2.2.2-cryptand at –30 °C. The majority of the 2-Ln series have been reported previously by the salt metathesis reactions of 3 eq. KCptt with parent LnCl3, and these methods were adapted here to afford 2-Pr. Complexes 1-Ln and 2-Pr were characterized by single crystal XRD, elemental analysis, ATR-IR and UV-Vis-NIR spectroscopy; 1-La and 2-Pr were additionally characterized by c.w. EPR spectroscopy, and variable temperature magnetic susceptibility measurements were performed on 2-Pr. During attempts to synthesize 2-Nd and 2-Sm we also obtained small crops of crystals of [Nd(Cptt)2(μ-I)]2 (3) and [Sm(Cptt)2(μ-Cl)]2·C7H8 (4·C7H8), respectively; these complexes were also structurally authenticated. The combination of data obtained indicate that the Ln(II) centers in 1-Ln adopt 4fn5d1 electron configurations, in common with other literature examples of [Ln(CpR)3]– anions (CpR = substituted cyclopentadienyl) for these metals.

Low-valent N-coordinated cations and dications of heavier group 14 elements are of great interest in recent years. Their unique electronic structure gives them an ambiphilic character, as they contain both a lone electron pair and an empty p-orbital on the central metal atom. Thanks to their nucleophilic character, these compounds can act as ligands in transition metal chemistry, and conversely, their electrophilic character allows them to interact with a wide range of organic substrates and thus replace catalysts based on transition metal complexes in many chemical transformations. The aim of this article is to summarize the synthesis of N-coordinated ionic compounds of heavier group 14 elements with their subsequent reactivity towards various nucleophiles and electrophiles.

The size induced phase transition for non-cubic β-pyrochlore compounds Rb0.95NbxMo2-xO6.475-0.5x (x = 1.31–1.663) has been studied in detail. The Rb0.95NbxMo2-xO6.475-0.5x (x = 1.31–1.663) powders with different size particles have been prepared and investigated by X-ray powder diffraction analysis and scanning electron microscopy with X-ray microanalysis. The Rb0.95Nb1.5Mo0.5O5.73 and Rb0.95Nb1.375Mo0.625O5.79 powders consisted of ~ 20 µm crystals possess orthorhombic Pnma symmetry, whereas the same powders with particle size less 1 µm have cubic Fd-3m and characterized by decreasing Rb content - Rb0.7Nb1.5Mo0.5O5.58 and Rb0.9Nb1.625Mo0.375O5.62. The crystal structure of Rb0.7Nb1.5Mo0.5O5.58 cubic phase refinement has been performed using the Rietveld method; and crystallographic reasons of structure reconstruction have been discussed. The electronic structure and band gap of Rb0.95NbxMo2-xO6.475-0.5x (x = 1.31–1.663) compounds have been studied. Moreover the comparison of electronic structure for cubic and orthorhombic phases has been performed.

3-Formyl- and 3-dicyanovinyl-functionalized oxido-molybdenum corroles have been synthesized and utilized as an efficient catalyst with high TOF values (59801–71174 h⁻¹) for oxidative bromination for a wide variety of phenol derivatives at room temperature in water in the presence of KBr/H₂O₂/HClO₄ as brominating agent.

Abstract

Two new β-functionalized oxidomolybdenum(V) corroles, oxido[3-formyl-5,10,15-triphenylcorrolato]molybdenum(V) (Mo-1) and oxido[3-dicyanovinyl-5,10,15-triphenylcorrolato]molybdenum(V) (Mo-2) were synthesized and characterized by various spectroscopic techniques and electrochemical studies. Mo-2 manifests splitted B bands due to x and y polarizations and highly red shifted longest B and Q bands due to the electron-deficient nature of the dicyanovinyl group. EPR data showed that these complexes exhibit an axial compression with d _xy ¹ configuration. DFT studies revealed that HOMO and LUMO orbitals are stabilized in Mo-2 relative to Mo-1. Mo-1 exhibits two successive reversible reductions and two oxidation potentials in cyclic voltammetry. Surprisingly, Mo-2 exhibits three successive reversible reductions and two oxidations; the one extra reduction could possibly be due to the reduction of the dicyanovinyl moiety. The catalytic activities of Mo-1 and Mo-2 for the oxidative bromination of various phenols using H₂O₂-KBr-HClO₄ mixture in water have been explored and exhibited excellent activity at a very low catalyst loading of 0.0030 and 0.0028 mol%, respectively. Both synthesized β-functionalized Mo(V) corroles manifest much higher conversion and TOF (59801–71174 h⁻¹) for oxidative bromination of phenols relative to earlier reported meso-functionalized Mo(V) corroles (20781–61646 h⁻¹). Hence, Mo-1 and Mo-2 mimic vanadium bromoperoxidase (VBPO) and act as functional models for these catalytic applications. These catalysts were reused upto 3 cycles and showed conversion rate upto 82 % indicating their excellent thermal and chemical stabilities.

A nanosheet catalyst consisting of MoC/Mo₂C-coated carbon nanotubes was prepared by hydrothermal synthesis and annealing, which exhibited excellent catalytic performance and stability for electrolytic water in a two-electrode system.

Abstract

The conventional electrolytic water-splitting process for hydrogen production is plagued by high energy consumption, low efficiency, and the requirement of expensive catalysts. Therefore, finding effective, affordable, and stable catalysts to drive this reaction is urgently needed. We report a nanosheet catalyst composed of carbon nanotubes encapsulated with MoC/Mo₂C, the Ni@MoC-700 nanosheet showcases low overpotentials of 275 mV for the oxygen evolution reaction and 173 mV for the hydrogen evolution reaction at a current density of 10 mA ⋅ cm⁻². Particularly noteworthy is its outstanding performance in a two-electrode system, where a cell potential of merely 1.64 V is sufficient to achieve the desired current density of 10 mA ⋅ cm⁻². Furthermore, the catalyst demonstrates exceptional durability, maintaining its activity over a continuous operation of 40 hours with only minimal attenuation in overpotential. These outstanding activity levels and long-term stability unequivocally highlight the promising potential of the Ni@MoC-700 catalyst for large-scale water-splitting applications.