“All-Three-in-One”: A New Bismuth–Tellurium–Borate Bi₃TeBO₉ Exhibiting Strong Second Harmonic Generation Response

A new nonlinear optical (NLO) material, Bi₃TeBO₉ (BTBO), is successfully grown from high temperature solution method. BTBO crystallizes in a polar space group of <i>P</i>6₃ with a framework structure composed of [Bi₃O₉] blocks, with TeO₆ and BO₃ interconnection. It is interesting that in the BTBO structure three types of NLO-active units, including stereochemically active lone pair cations (Bi³⁺ cations), second-order Jahn–Teller distorted octahedra (TeO₆ octahedra) and π-orbital planar groups (BO₃ groups), simultaneously exist. The additive contribution from these three types of groups results in an extremely large second harmonic generation (SHG) response in BTBO (about 20 times that of KDP), exhibiting the largest SHG effect among the known borate NLO materials. The enhancement of the nonlinear optical property is elucidated by the first-principles analysis

“All-Three-in-One”: A New Bismuth–Tellurium–Borate Bi₃TeBO₉ Exhibiting Strong Second Harmonic Generation Response

A new nonlinear optical (NLO) material, Bi₃TeBO₉ (BTBO), is successfully grown from high temperature solution method. BTBO crystallizes in a polar space group of <i>P</i>6₃ with a framework structure composed of [Bi₃O₉] blocks, with TeO₆ and BO₃ interconnection. It is interesting that in the BTBO structure three types of NLO-active units, including stereochemically active lone pair cations (Bi³⁺ cations), second-order Jahn–Teller distorted octahedra (TeO₆ octahedra) and π-orbital planar groups (BO₃ groups), simultaneously exist. The additive contribution from these three types of groups results in an extremely large second harmonic generation (SHG) response in BTBO (about 20 times that of KDP), exhibiting the largest SHG effect among the known borate NLO materials. The enhancement of the nonlinear optical property is elucidated by the first-principles analysis

Biomimetic Mineralization Guided One-Pot Preparation of Gold Clusters Anchored Two-Dimensional MnO₂ Nanosheets for Fluorometric/Magnetic Bimodal Sensing

A novel fluorometric/magnetic bimodal sensor is reported based on gold nanoclusters (Au NCs)-anchored two-dimensional (2D) MnO₂ nanosheets (Au NCs–MnO₂) that are synthesized through a one-pot biomimetic mineralization process. Bovine serum albumin (BSA) was used as the template to guide the formation and assembly of the Au NCs–MnO₂ under physiological conditions and without use of any strong oxidizing agent and toxic surfactants as well as organic solvent. The fluorescence of Au NCs was first quenched by MnO₂ nanosheets, while upon H₂O₂ introduction, the MnO₂ nanosheets can be sensitively and selectively reduced to Mn²⁺ with enhanced magnetic resonance (MR) signal and rapid recovery of Au NCs fluorescence simultaneously. This dual-modal strategy can overcome the weakness of a single-fluorescence detection mode. A linear range of 0.06–2 μM toward H₂O₂ was obtained for the fluorescence mode, whereas the MR mode also allowed detection of H₂O₂ at a concentration that ranged from 0.01 to 0.2 mM. Benefiting from the BSA molecule residual on the product surface, the as-prepared Au NCs–MnO₂ displays low cytotoxicity and good biocompatibility. Importantly, the successful application of Au NCs–MnO₂ for analysis of H₂O₂ in biological samples and cells indicates that the integration of Au NCs fluorescence with Mn²⁺ MR response provides a promising bimodal sensing platform for H₂O₂ in vivo monitoring

Structural Evolution in BaSn₂F₅X (X = Cl, Br, I): A Family of Alkaline Earth Metal Tin Mixed Halides

As the first family of Sn-based alkaline earth metal mixed halides, three new compounds, BaSn₂F₅X (X = Cl, Br, and I), are synthesized by hydrothermal method. These compounds are crystallized in the centrosymmetric space groups of <i>P</i>2₁/<i>c</i>, <i>P</i>4/<i>nmm</i>, and <i>Pmma</i> for BaSn₂F₅Cl, BaSn₂F₅Br, and BaSn₂F₅I, respectively, and their microscopic frameworks are all composed of the fundamental structural unit [SnF₄]^2– and its derivatives ([SnF₄Cl]^3– and [SnF₅]^3– groups). Interestingly, the structures in BaSn₂F₅X are significantly changed from one-dimensional (1D) to two-dimensional (2D) and then to 1D motifs as X varies from Cl, Br, to I. Structural analysis combined with theoretical calculations reveals that the structural diversities are caused by the difference of ionic radius and electronegativity of X^– anions as well as the orientation of the lone-pair electrons on Sn²⁺ cations. Moreover, the optical, electronic, and thermal properties for these three compounds are determined. This work provides a representative example to show how microscopic ions influence the structures, thus in favor of the design for new mixed halides, a type of important functional materials with many optoelectronic applications

1,2-Dichloroethane Deep Oxidation over Bifunctional Ru/Ce_<i>x</i>Al_<i>y</i> Catalysts

Ru/Ce_<i>x</i>Al_<i>y</i> catalysts were synthesized with impregnation of RuCl₃ aqueous solution on Ce_<i>x</i>Al_<i>y</i> (Al₂O₃–CeO₂) and used in 1,2-dichloroethane (1,2-DCE) oxidation. Characterization by X-ray diffraction, Raman, NH₃-temperature-programmed desorption (TPD), CO₂-TPD, X-ray photoelectron spectroscopy, and H₂-temperature-programmed reduction indicates that CeO₂ exists as a form of face-centered cubic fluorite structure, whereas the chemical states and the structure of Ru species are dependent on the Ce content. The reducibility and acidity of catalysts increase with Ce/Ce + Al ratio. However, the latter is promoted only in a Ce/Ce + Al range of 0–0.25 and then decreases quickly. Ru/Ce_<i>x</i>Al_<i>y</i> catalysts have considerable activity for 1,2-DCE combustion. TOF_Ru of 1,2-DCE oxidation increases with strong acid, which is ascribed to a synergy of reducibility and acidity. Ru greatly inhibits the chlorination through the decreases in both Cl deposition and CH₂CHCl formation. High stability of Ru/Ce₁₀Al₉₀ maintains at 280 °C for at least 25 h with CO₂ selectivity of 99% or higher. In situ Fourier transform infrared spectroscopy indicates that 1,2-DCE dissociates to form ClCH₂–CH₂O– species, which is an intermediate species for the production of CH₃CHO and CH₂CHCl, the former responsible for deep oxidation

Two-Dimensional-Layered Perovskite ALaTa₂O₇:Bi³⁺ (A = K and Na) Phosphors with Versatile Structures and Tunable Photoluminescence

Topological chemical reaction methods are indispensable for fabricating new materials or optimizing their functional properties, which is particularly important for two-dimensional (2D)-layered compounds with versatile structures. Herein, we demonstrate a low-temperature (∼350 °C) ion exchange approach to prefabricate metastable phosphors ALa_1–<i>x</i>Ta₂­O₇:<i>x</i>Bi³⁺ (A = K and Na) with RbLa_1–<i>x</i>­Ta₂O₇:<i>x</i>Bi³⁺ serving as precursors. The as-prepared ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) share the same Dion–Jacobson type 2D-layered perovskite phase, and photoluminescence analyses show that ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) phosphors exhibit broad emission bands peaking at 540, 550, and 510 nm, respectively, which are attributed to the nonradiative transition of Bi³⁺ from excited state ³P₁ or ³P₀ to ground state ¹S₀. The various Bi³⁺ local environments at the crystallographic sites enable the different distributions of emission and excitation spectra, and the photoluminescence tuning of ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) phosphors are realized through alkali metal ion exchange. Notably, the combination of superior trivalent bismuth emission and low-temperature ion exchange synthesis leads to a novel yellow-emitting K­(La_0.98Bi_0.02)­Ta₂O₇ phosphor which is successfully applied in a white LED device based on a commercially available 365 nm LED chip. Our realizable cases of this low-temperature ion exchange strategy could promote exploration into metastable phosphors with intriguing properties

Sr₃BeB₆O₁₃: A New Borate in the SrO/BeO/B₂O₃ System with Novel Tri-Six-Membered Ring (BeB₆O₁₅)^10– Building Block

A new polyborate Sr₃BeB₆O₁₃ has been synthesized and grown by the traditional solid-state reaction method and spontaneous crystallization flux method. It crystallizes in orthorhombic space group <i>Pnma</i> (No. 62) with the following unit cell dimensions: <i>a</i> = 12.775(3) Å, <i>b</i> = 10.029(2) Å, <i>c</i> = 8.0453(16) Å, and <i>Z</i> = 4. The crystal is characterized by an infinite two-dimensional network with a tri-six-membered ring (BeB₅O₁₃)^9– anionic group, which was first found in beryllium borates. Ultraviolet (UV)–visible–near-infrared diffuse reflectance spectroscopy demonstrates that its UV cutoff edge is below 200 nm, and the first-principles electronic structure calculations reveal its energy band gap of 7.03 eV (∼175 nm). Thermal analysis exposes its incongruent feature at 1043 °C. IR spectroscopy measurements are consistent with the crystallographic study. These data reveal that this crystal would be applied as a deep-ultraviolet optical material

Sr₈MgB₁₈O₃₆: a New Alkaline-Earth Borate with a Novel Zero-Dimensional (B₁₈O₃₆)^18– Anion Ring

A new polyborate, Sr₈MgB₁₈O₃₆, has been synthesized. Its crystal structure was determined from single-crystal X-ray diffraction data, and characterizations were made by differential scanning calorimetry, Fourier transform IR, UV–vis–near-IR diffuse-reflectance, and first-principles calculations. The structure of Sr₈MgB₁₈O₃₆ contains a novel isolated anionic groupan 18-membered ring (B₁₈O₃₆)^18–, which is the first found in borates

Visible-Light-Responsive Chalcogenide Photocatalyst Ba₂ZnSe₃: Crystal and Electronic Structure, Thermal, Optical, and Photocatalytic Activity

Visible-light-responsive photocatalytic materials have important applications. In this article, through inserting electropositive ion Ba²⁺ into the three-dimensional framework of ZnSe, a one-dimensional chalcogenide Ba₂ZnSe₃ has been obtained by traditional solid-state reaction. It crystallizes in orthorhombic centrosymmetric space group <i>Pnma</i> with unit cell parameters of <i>a</i> = 9.0744(2) Å, <i>b</i> = 4.4229(1) Å, <i>c</i> = 17.6308(4) Å, and <i>Z</i> = 4. Its structure features [ZnSe₃]^4– anionic straight chains parallel to the <i>b</i> direction, which are further separated by Ba²⁺ cations filling in the cavities. On the basis of the UV–vis–NIR diffuse reflectance spectroscopy, Ba₂ZnSe₃ possesses a typical direct band gap of 2.75 eV, which is in good agreement with the electronic structure calculation. Moreover, Ba₂ZnSe₃ shows good visible-light-responsive photocatalytic activity and excellent thermal stability and cyclability, which are favorable for its application

Two-Dimensional-Layered Perovskite ALaTa₂O₇:Bi³⁺ (A = K and Na) Phosphors with Versatile Structures and Tunable Photoluminescence

Topological chemical reaction methods are indispensable for fabricating new materials or optimizing their functional properties, which is particularly important for two-dimensional (2D)-layered compounds with versatile structures. Herein, we demonstrate a low-temperature (∼350 °C) ion exchange approach to prefabricate metastable phosphors ALa_1–<i>x</i>Ta₂­O₇:<i>x</i>Bi³⁺ (A = K and Na) with RbLa_1–<i>x</i>­Ta₂O₇:<i>x</i>Bi³⁺ serving as precursors. The as-prepared ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) share the same Dion–Jacobson type 2D-layered perovskite phase, and photoluminescence analyses show that ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) phosphors exhibit broad emission bands peaking at 540, 550, and 510 nm, respectively, which are attributed to the nonradiative transition of Bi³⁺ from excited state ³P₁ or ³P₀ to ground state ¹S₀. The various Bi³⁺ local environments at the crystallographic sites enable the different distributions of emission and excitation spectra, and the photoluminescence tuning of ALa_0.98­Ta₂O₇:0.02 Bi³⁺ (A = Rb, K, and Na) phosphors are realized through alkali metal ion exchange. Notably, the combination of superior trivalent bismuth emission and low-temperature ion exchange synthesis leads to a novel yellow-emitting K­(La_0.98Bi_0.02)­Ta₂O₇ phosphor which is successfully applied in a white LED device based on a commercially available 365 nm LED chip. Our realizable cases of this low-temperature ion exchange strategy could promote exploration into metastable phosphors with intriguing properties