Exploring short-wavelength birefringent crystals triggering cooperative arrangement between different π-conjugated groups.

We herein reported our strategy to assemble planar π-conjugated [B(OH)] and [CO]/[HCO]/[CO] functional groups to explore short-wavelength birefringent crystals. Three compounds, KCO·B(OH), Cs(HCO)(CO)·[B(OH)] and K(CO)·B(OH), which all exhibit a layered structure favorable for generating large optical anisotropy, were synthesized and characterized. The strategy of assembling π-conjugated [B(OH)] and C-O functional modules shows the potential to explore promising UV birefringent materials.

Observing the Surface Termination of LaScO Perovskite Using Solid-State Nuclear Magnetic Resonance.

Materials with well-defined surfaces are drawing increased attention for the design of bespoke catalysts and nanomaterials. Gaining a detailed understanding of the surfaces of these materials is an important challenge, which is often complicated by surface polymorphism and dynamic restructuring. We introduce the use of surface-enhanced NMR spectroscopy for the observation of such surfaces, focusing on LaScO as an example.

Informatics-Based Learning of Oxygen Vacancy Ordering Principles in Oxygen-Deficient Perovskites.

Ordered oxygen vacancies (OOVs) in perovskites can exhibit long-range order and may be used to direct materials properties through modifications in electronic structures and broken symmetries. Based on the various vacancy patterns observed in previously known compounds, we explore the ordering principles of oxygen-deficient perovskite oxides with O stoichiometry to identify other OOV variants. We performed first-principles calculations to assess the OOV stability on a data set of 50 OOV structures generated from our bespoke algorithm.

Supported Platinum Nanoparticles Catalyzed Carbon-Carbon Bond Cleavage of Polyolefins: Role of the Oxide Support Acidity.

Supported platinum nanoparticle catalysts are known to convert polyolefins to high-quality liquid hydrocarbons using hydrogen under relatively mild conditions. To date, few studies using platinum grafted onto various metal oxide (MO) supports have been undertaken to understand the role of the acidity of the oxide support in the carbon-carbon bond cleavage of polyethylene under consistent catalytic conditions. Specifically, two Pt/MO catalysts (MO = SrTiO and SiO-AlO; Al = 3.

Chiral and Polar Duality Design of Heteroanionic Compounds: Sr Ge O S Based on [Sr OGeS ] and [Sr SGeS ] Groups.

Chirality and polarity are the two most important and representative symmetry-dependent properties. For polar structures, all the twofold axes perpendicular to the principal axis of symmetry should be removed. For chiral structures, all the mirror-related symmetries and inversion axes should be removed.

Rapid and Reversible Lithium Insertion in the Wadsley-Roth-Derived Phase NaNbO.

The development of new high-performing battery materials is critical for meeting the energy storage requirements of portable electronics and electrified transportation applications. Owing to their exceptionally high rate capabilities, high volumetric capacities, and long cycle lives, Wadsley-Roth compounds are promising anode materials for fast-charging and high-power lithium-ion batteries. Here, we present a study of the Wadsley-Roth-derived NaNbO phase and examine its structure and lithium insertion behavior.

Beyond π-π Stacking: Understanding Inversion Symmetry Breaking in Crystalline Racemates.

The design of noncentrosymmetric (NCS) solid state materials, specifically how to break inversion symmetry between enantiomers, has intrigued chemists, physicists, and materials scientists for many years. Because the chemical complexity of molecular racemic building units is so varied, targeting these materials is poorly understood. Previously, three isostructural racemic compounds with a formula of [Cu(HO)(bpy)][MF]·2HO (bpy = 2,2'=bipyridine; M = Ti, Zr, Hf) were shown to crystallize in the NCS space group 2, of polar, achiral crystal class 2.

Wet to Dry Controls Lanthanide Scandate Synthesis.

The choice of temperature and gas conditions used in a water pressure-controlled reactor is guided by density functional theory (DFT) to synthesize nearly phase-pure lanthanide scandate nanoparticles (LnScO, Ln = La, Nd, Sm, Gd). In this synthetic method, low water-vapor partial pressures, well below water's gas liquidus, inhibit particle growth, while an excess of water vapor results in undesired rare-earth hydroxide and oxyhydroxide secondary phases. The optimal humidity for high-purity LnScO particle synthesis is shown to vary with the lanthanide; DFT is used to calculate the thermodynamics of secondary phase formation for each lanthanide tested such that the role of water vapor may be quantified and used to maintain phase purity (greater than 96 mol %) across the series.

NaRb(BO(OH))(BO) Featuring Noncentrosymmetry, Chirality, and the Linear Anionic Group BO.

Noncentrosymmetric (NCS) structures are of particular interest owing to their symmetry-dependent physical properties, e.g., pyroelectricity, ferroelectricity, piezoelectricity, and nonlinear optical (NLO) behavior.

Two Distinct Cu(II)-V(IV) Superexchange Interactions with Similar Bond Angles in a Triangular "CuV" Fragment.

The strength and sign of superexchange interactions are often predicted on the basis of the bond angles between magnetic ions, but complications may arise in situations with a nontrivial arrangement of the magnetic orbitals. We report on a novel molecular tetramer compound [Cu(HO)dmbpy][VOF] (dmbpy = 4,4'-dimethyl-2,2'-bipyridyl) that is composed of triangular "CuV" fragments and displays a spin gap behavior. By combining first-principles calculations and electronic models, we reveal that superexchange Cu-V interactions carry drastically different coupling strengths along two Cu-F-V pathways with comparable bond angles in the triangular "CuV" fragment.

Triple-Wavelength Lasing with a Stabilized β-LaBSiO:Nd Crystal.

Multi-wavelength lasers, especially the triple-wavelength laser around 1060 nm, could be produced by the F → I transition of Nd and present numerous challenges and opportunities in the field of optoelectronics. The Nd-doped high-temperature phase of LaBSiO (β-LBSO) is an ideal crystal to produce triple-wavelength lasers; however, the crystal growth is challenging because of the phase transition from β-LBSO to low-temperature phase (α-LBSO) at 162 °C. This phase transition is successfully suppressed when the doping content of Nd is larger than 6.

Strong Nonlinearity Induced by Coaxial Alignment of Polar Chain and Dense [BO ] Units in CaZn (BO ).

Discovery of new efficient nonlinear optical (NLO) materials with large second-order nonlinearity for the short-wave ultraviolet spectral region (λ ≤266 nm, PM=phase-matching) is still very challenging. Herein, a new beryllium-free borate CaZn (BO ) with Sr Be B O (SBBO) double-layered like configuration was rationally designed, which not only preserves the structural merits but also eliminates the limitations of the SBBO crystal. CaZn (BO ) shows a large PM second harmonic generation (SHG) reponse of 3.

Low Thermal Conductivity in Heteroanionic Materials with Layers of Homoleptic Polyhedra.

Although BiAgOSe, an analogue of a well-studied thermoelectric material BiCuOSe, is thermodynamically stable, its synthesis is complicated by the low driving force of formation from the stable binary and ternary intermediates. Here we have developed a "subtraction strategy" to suppress byproducts and produce pure phase BiAgOSe using hydrothermal methods. Electronic structure calculations and optical characterization show that BiAgOSe is an indirect bandgap semiconductor with a bandgap of 0.

Scalable Synthesis of Pt/SrTiO Hydrogenolysis Catalysts in Pursuit of Manufacturing-Relevant Waste Plastic Solutions.

An improved hydrothermal synthesis of shape-controlled, size-controlled 60 nm SrTiO nanocuboid (STO NC) supports, which facilitates the scalable creation of platinum nanoparticle catalysts supported on STO (Pt/STO) for the chemical conversion of waste polyolefins, is reported herein. This synthetic method (1) establishes that STO nucleation prior to the hydrothermal treatment favors nanocuboid formation, (2) produces STO NC supports with average sizes ranging from 25 to 80 nm with narrow size distributions, and (3) demonstrates how SrCO formation and variation in solution pH prevent the formation of STO NCs. The STO synthesis was scaled-up and conducted in a 4 L batch reactor, resulting in STO NCs of comparable size and morphology ( = 22.

Perovskite-like KTiOF Exhibits (3 + 1)-Dimensional Commensurate Structure Induced by Octahedrally Coordinated Potassium Ions.

Elpasolite- and cryolite-type oxyfluorides can be regarded as superstructures of perovskite and exhibit structural diversity. While maintaining a similar structural topology with the prototype structures, changes in the size, electronegativity, and charge of cation and/or anion inevitably lead to structural evolution. Therefore, the nominal one-to-one relation suggested by a doubled formula of perovskite does not guarantee a simple 2-fold superstructure for many cases.

Expanding the Ambient-Pressure Phase Space of CaFeO-Type Sodium Postspinel Host-Guest Compounds.

CaFeO-type sodium postspinels (Na-CFs), with Na occupying tunnel sites, are of interest as prospective battery electrodes. While many compounds of this structure type require high-pressure synthesis, several compounds are known to form at ambient pressure. Here we report a large expansion of the known Na-CF phase space at ambient pressure, having successfully synthesized NaCrTiO, NaRhTiO, NaCrSnO, NaInSnO, NaMgTiO, NaFeTiO, NaMgSnO, NaMnSnO, NaFeSnO, NaCoSnO, NaNiSnO, NaCuSnO, NaZnSnO, NaCdSnO, NaScSbO, NaInSbO, and several solid solutions.

Crystal structures of two copper(I)-6,6'-dimethyl-2,2'-bipyridyl (dmbpy) compounds, [Cu(dmbpy)][F]·HO ( = Zr, Hf; = 1.134, 0.671).

The syntheses and crystal structures of two bimetallic mol-ecular compounds, namely, bis[bis-(6,6'-dimethyl-2,2'-bi-pyridine)-copper(I)] hexa-fluorido-zir-con-ate(IV) 1.134-hydrate, [Cu(dmbpy)][ZrF]·1.134HO (dmbpy = 6,6'-di-methyl-2,2'-bipyri-dyl, CHN), (I), and bis[bis-(6,6'-dimethyl-2,2'-bi-pyr-idine)-copper(I)] hexa-fluorido-hafnate(IV) 0.

Synthetic Lubricants Derived from Plastic Waste and their Tribological Performance.

The energy efficiency, mechanical durability, and environmental compatibility of all moving machine components rely heavily on advanced lubricants for smooth and safe operation. Herein an alternative family of high-quality liquid (HQL) lubricants was derived by the catalytic conversion of pre- and post-consumer polyolefin waste. The plastic-derived lubricants performed comparably to synthetic base oils such as polyalphaolefins (PAOs), both with a wear scar volume (WSV) of 7.

Expanding the chemistry of borates with functional [BO] anions.

More than 3900 crystalline borates, including borate minerals and synthetic inorganic borates, in addition to a wealth of industrially-important boron-containing glasses, have been discovered and characterized. Of these compounds, 99.9 % contain only the traditional triangular BO and tetrahedral BO units, which polymerize into superstructural motifs.

Fluoridation of HfO.

Fluoridation of HfO was carried out with three commonly used solid-state fluoridation agents: PVDF, PTFE, and NHHF. Clear and reproducible differences are observed in the reaction products of the fluoropolymer reagents and NHHF with the latter more readily reacting in air. Strong evidence of distinct, previously unreported hafnium oxyfluoride phases is produced by both reactions, and efforts to isolate them were successful for the air-NHHF reaction.

Crystal structures of [Cu(phen)(HO)(F)]·HO ( = Ti, Zr, Hf) and [Cu(phen)(HO)F][HfF]·HO.

The crystal structures of three bridged bimetallic mol-ecular compounds, namely, tri-aqua-2κ -μ-fluorido-penta-fluorido-1κ -(1,10-phenanthroline-2κ ,')copper(II)titanium(IV) monohydrate, [Cu(TiF)(phen)(HO)]·HO (phen is 1,10-phenanthroline, CHN), (I), tri-aqua-2κ -μ-fluorido-penta-fluorido-1κ -(1,10-phenanthroline-2κ ,')copper(II)zirconium(IV) monohydrate, [Cu(ZrF)(phen)(HO)]·HO, (II), and tri-aqua-2κ -μ-fluorido-penta-fluorido-1κ -(1,10-phenanthroline-2κ ,')copper(II)hafnium(IV) monohydrate, [Cu(HfF)(phen)(HO)]·HO, (III), and one mol-ecular salt, bis-[diaqua-fluorido-(1,10-phenanthroline-κ ,')copper(II)] hexa-fluorido-hafnate(IV) dihydrate, [CuF(phen)(HO)][HfF]·2HO, (IV), are reported. The bridged bimetallic compounds adopt Λ-shaped configurations, with the octa-hedrally coordinated copper(II) center linked to the fluorinated early transition metal a fluoride linkage. The extended structures of these Λ-shaped compounds are organized through both intra- and inter-molecular hydrogen bonds and inter-molecular π-π stacking.

Crystal structures of three copper(II)-2,2'-bi-pyridine (bpy) compounds, [Cu(bpy)(HO)][SiF]·4HO, [Cu(bpy)(TaF)] and [Cu(bpy)][TaF] and a related coordination polymer, [Cu(bpy)(HO)SnF] .

We report the hydro-thermal syntheses and crystal structures of aqua-bis-(2,2'-bi-pyridine-κ ,')copper(II) hexa-fluorido-silicate tetra-hydrate, [Cu(bpy)(HO)][SiF]·4HO (bpy is 2,2'-bi-pyridine, CHN), (I), bis-(2,2'-bi-pyridine-3κ ,')-di-μ-fluorido-1:3κ :;2:3κ :-deca-fluorido-1κ ,2κ -ditantalum(V)copper(II), [Cu(bpy)(TaF)], (II), tris-(2,2'-bi-pyridine-κ ,')copper(II) bis[hexa-fluorido-tantalate(V)], [Cu(bpy)][TaF], (III), and -poly[[di-aqua-(2,2'-bi-pyridine-κ ,')copper(II)]-μ-fluorido-tetra-fluorido-tin-μ-fluorido], [Cu(bpy)(HO)SnF] , (IV). Compounds (I), (II) and (III) contain locally chiral copper coordination complexes with , , and symmetry, respectively. The extended structures of (I) and (IV) are consolidated by O-H⋯F and O-H⋯O hydrogen bonds.

Borates: A Rich Source for Optical Materials.

The primary goal of this review is to present a clear chemical perspective of borates in order to stimulate and facilitate the discovery of new borate-based optical materials. These materials, which exhibit structures as varied as they are complex, are needed to meet the urgent technological milestones. In the current period of rapid sociotechnological breakthroughs, the need for the rational design and discovery of novel borates with superior performance is greater than ever before.

Multimodal Structure Solution with F NMR Crystallography of Spin Singlet Molybdenum Oxyfluorides.

Complex crystal structures with subtle atomic-scale details are now routinely solved using complementary tools such as X-ray and/or neutron scattering combined with electron diffraction and imaging. Identifying unambiguous atomic models for oxyfluorides, needed for materials design and structure-property control, is often still a considerable challenge despite their advantageous optical responses and applications in energy storage systems. In this work, NMR crystallography and single-crystal X-ray diffraction are combined for the complete structure solution of three new compounds featuring a rare triangular early transition metal oxyfluoride cluster, [MoOF].

Machine-Learning-Assisted Synthesis of Polar Racemates.

Racemates have recently received attention as nonlinear optical and piezoelectric materials. Here, a machine-learning-assisted composition space approach was applied to synthesize the missing M = Ti, Zr members of the Δ,Λ-[Cu(bpy)(HO)][MF]·3HO (M = Ti, Zr, Hf; bpy = 2,2'-bipyridine) family (space group: 2). In each (CuO, MO)/bpy/HF() (M = Ti, Zr, Hf) system, the polar noncentrosymmetric racemate (M-NCS) forms in competition with a centrosymmetric one-dimensional chain compound (M-CS) based on alternating Cu(bpy)(HO) and MF basic building units (space groups: Ti-CS (), Zr-CS (1̅), Hf-CS (2/)).