Themed collection Spotlight Collection: Mixed-Anion Compounds

Mixed-anion coordination around Eu³⁺ ions affects the luminescence properties related to the 4f–4f and charge transfer transitions.

The emerging field of spintro-catalysis, at the interface of catalysis and spintronics, offers a compelling strategy to overcome long-standing limitations in catalytic reactions involving spin-sensitive intermediates.

This Frontiers article discusses the recent progress and challenges of non-centrosymmetric oxychalcogenides in the IR nonlinear optical field.

Using tetrabutylammonium cations, we were able to perform polyoxometalate (POM) synthesis in organic solvents. This enabled us to incorporate Al and Si into the POM framework and thoroughly characterise the resulting products.

A mid-infrared functional crystal, Cs₂Pb₂₄O₂₁I₈(3Pb₈O₇I₂·2CsI), with aligned rod-like [Pb₈O₇]²⁺ chains and enhanced symmetry was rationally designed and synthesized by introducing the salt-inclusion compound CsI into heavy metal oxyhalides.

La_xSr_2−xCo_0.5Ir_0.5O_4−yH_y oxyhydride phases have hydride ions located exclusively on their equatorial anion sites.

Novel perovskite-type oxyhydrides, BaLnO₂H (Ln = Tb–Lu), were synthesized by a mechanochemical method. These compounds functioned as efficient catalyst supports of a Ru catalyst for ammonia synthesis due to strong electron donation.

The catalytic reduction of CO₂ to HCOOH was achieved using Zn(OH)(NO₃) and Zn₃(OH)₄(NO₃)₂ under visible light with a Ru(II) photosensitizer and electron donor.

A systematic workflow considering both the octahedral tilting and anion ordering in mixed-anion perovskites is applied to predict potential new oxyfluoride, oxynitride, and nitrofluoride perovskites.

The oxygen partial pressure critically governs the sequential phase transformation from Ta₂O₅ to Ta₃N₅via β-TaON. An oxygen flow rate of 0.25 L h⁻¹ defines the narrow synthesis region necessary for obtaining phase-pure β-TaON.

Partial congener substitution widens the band gap while preserving a strong nonlinear optical response.

A new selenohalide Cs₉Si₈Se₂₀Cl with rare [Si₄Se₁₀] T2-supertetrahedra and unprecedented [CsSe₇Cl] polyhedra has been synthesized by the flux method. The introduction of halide results a wide band gap (3.075 eV) in the selenide.

The novel oxide chloride Ca₂TlO₃Cl has a layered crystal structure and reacts photo-electrochemically to simulated sun light.

(CH₃NH₃)₂Co(NCS)₄ and (CH₃NH₃)₃CoI₄(NCS) with isolated Co²⁺-centered tetrahedra were successfully synthesized. The effective magnetic moment and Curie constant decrease with the substitution of I⁻ by NCS⁻.

Eu²⁺₃Eu³⁺Ta₂ON₅ is an anion deficient oxynitride with square pyramidal coordination for Ta that shows ferromagnetic order of Eu²⁺ ions below 20 K, with superexchange interactions enhanced by nitride-reinforced hybridization of Eu–(N/O)–Eu bonds.

Chemical substitution and physical pressure drive Martensitic-like polymorphic transitions among FeOCl-, SmSI-, and SrI₂-type structures in LnSI mixed-anion compounds, governed by the cation-to-anion radius ratio as a unifying geometric factor.

Single crystals of a series of non-centrosymmetric oxysulfides Ln₃Ga₃Ge₂S₃O₁₀ (Ln = La, Ce, Pr, Nd) are grown out of molten chloride fluxes. The Ga and Ge atoms take heteroleptic and homoleptic coordination geometries, respectively.

The ferroelectricity and phase transition of the solid solution of relaxor ferroelectric dabcoHI and dabcoHBr were studied.

Tb₂O₂NCN offers a conjunction of luminescent thermometry and magnetocaloric effects. Due to two competing effects of thermal quenching, Tb₂O₂NCN may be used in low-temperature sensing, and it also lends itself to magnetic refrigeration.

As the Cl content increased in the organic–inorganic hybrid compounds, a structural transformation from 0D to 2D was observed. Halide mixing induced greater structural distortion, which was correlated with enhanced photoluminescence quantum yield.

Two distinct oxyfluorides were synthesized by annealing a brownmillerite SrCoO_2.5 (BM-SCO) thin film in MgF₂ powder through soft-chemistry reduction.

Reversible intercalation of lithium into the layered oxytelluride V₂Te₂O using both chemical and electrochemical methods is demonstrated.

Single crystals of rare-earth-based multi-anion chalcogenide iodides RE₃Si₂Se_xS_8−xI were synthesized via a reactive flux-assisted Boron Chalcogen Mixture method. All structures crystallize in the La₃Si₂O₈Cl structure type. Selenium incorporation improves optical properties.

Large and single crystals of a family of lamellar sodium methanesulfonates have been grown by ionic substitution of interlayer anions. Structural substitution affects crystal symmetry, growth habit, properties, and crystal quality.

Li₃PO_xS_4-x is synthesised using different sets of precursors, followed by a detailed structural analysis to establish links between the atomic structure and Li-ion conductivity of the materials.

Bi₃O₄Br appears to be nearly inactive for the alkaline oxygen evolution reaction while Mn^II doping into Bi₃O₄Br alters its electronic structure and makes it OER active. Mn–Bi₂O₃ evolves as the reactive species from the Mn–Bi₃O₄Br pre-catalyst.

Cuboid SrTaO₂N single crystals with an edge length of 300 μm were grown by an NH₃-assisted SrCl₂ flux method through evaporation of the flux.

Two novel metal chalcogenides Cs₂InPS₄X₂ (X = Cl, Br) were successfully synthesized and exhibit large optical band gaps induced by the [InS₄X₂]⁷⁻ mixed-anion groups.

The first alkali metal lead oxyhalide RbPb₈O₄Cl₉ is designed and synthesized. The compound shows a porous network framework built from unique [PbO₃Cl₃] and [PbOCl₅] mixed-anion groups and [RbCl₈] polyhedra.

Barium oxynitridosilicates were prepared at a low temperature from a mixture of BaCN₂ and SiO₂. Alkaline earth carbodiimides are a potential nitrogen source for achieving a low-temperature and energy-efficient process for a formation of oxynitrides.