Luminescent Lanthanide Selenites and Tellurites Decorated by MoO4 Tetrahedra or MoO6 Octahedra: Nd2MoSe2O10, Gd2MoSe3O12, La2MoTe3O12, and Nd2MoTe3O12

Ln2 F2 (OH2 )(MoO3 )2 (SeO3 )2 : Promising Multifunctional Nonlinear Optical Materials Created by Partial Fluorination Strategy under Corrosion Resistant Supercritical Reactions

It has historically been exceedingly challenging to create physically and chemically stable lanthanide compounds with strong second harmonic generation (SHG) due to their strong preference to central symmetry. In this work, five new non-centrosymmetric lanthanide selenites, namely, Ln2 F2 (OH2 )(MoO3 )2 (SeO3 )2 (Ln = Sm, Eu, Gd, Tb and Dy), are achieved by partial fluorination of the lanthanide oxygen polyhedron. An HF corrosion resistant supercritical hydrothermal method is developed, which is a facile and universal method for HF corrosion and high-temperature high-pressure environment. The title compounds displayed a novel 3D framework composed of 1D molybdenum selenite chains bridged by Ln2 F2 O12 (OH2 ) dimers. Their powder SHG responses showed a large difference, ranging from 1.0 to 9.0 × KH2 PO4 (KDP) at 1064 nm. The half-filled Gd compound exhibited very strong SHG efficiency of up to 1.2 × KTP (KTiOPO4 ) at 2050 nm. Compounds Tb and Gd are the first lanthanide selenites with SHG intensity reaching KTP level, which is very rare in this system. Furthermore, these compounds can also possess excellent physicochemical stability and strong luminescence emission, indicating that they are promising multifunctional nonlinear optical materials. This work offered an effective way for design and synthesis of multifunctional and high-performant nonlinear optical materials.

BaMo3O10 Polymorphs with Tunable Symmetries and Properties

Polymorphism is a well-known but important phenomenon in the field of solid-state chemistry. Crystalline materials can form various polymorphs and present drastically varied physical and chemical properties. Herein, systematic exploration of the BaO-MoO₃ binary system leads to the discovery of a new barium molybdate, α-BaMo₃O₁₀. The temperature-dependent phase transition from α-BaMo₃O₁₀ to β-BaMo₃O₁₀ is confirmed. The tunable linear and nonlinear optical properties induced by the phase transition are confirmed by both experimental and theoretical approaches. Also, β-BaMo₃O₁₀ is identified as a nonlinear-optical crystal for the first time. The origin of linear- and nonlinear-optical properties of BaMo₃O₁₀ polymorphs is confirmed by the additional theoretical means. This work indicates that a small change in the structure can induce tunable symmetries and thereby widely divergent optical properties.

KIn0.33IIITe0.67VITe2IVO7: Zirconolite-like Mixed-Valent Metal Oxide with a 3D Framework

We provide the material synthesis method, crystal structure information, and characterization of a novel mixed-valent metal oxide KIn_0.33^IIITe_0.67^VITe₂^IVO₇, closely related to zirconolite (CaZrTi₂O₇), a radioactive waste immobilized material, having a 3D framework. The reported metal oxide containing an alkali-metal cation (K⁺), main-group cation (In³⁺), tellurate, and tellurite has been synthesized as both single crystals and a pure polycrystalline phase through a hydrothermal synthesis method. Single-crystal X-ray diffraction indicates that KIn_0.33Te_2.67O₇ crystallizing in the orthorhombic space group Cmcm (No. 63) reveals a 3D framework structure with a 1D channel consisting of Te/InO₆ octahedra and TeO₄ polyhedra. An interesting transition reaction from KIn_0.33Te_2.67O₇ to KIn(TeO₃)₂ under hydrothermal conditions at 230 °C is discussed.

Structural Diversity of Molybdate Iodate and Fluoromolybdate: Syntheses, Structures, and Calculations on Na3(MoO4)(IO3) and Na3Cs(MoO2F4)2

The alkali-metal molybdate iodate Na₃(MoO₄)(IO₃) (I) and mixed-alkali-metal fluoromolybdate Na₃Cs(MoO₂F₄)₂ (II) were obtained via a mild hydrothermal reaction using a "Teflon-pouch" method. I crystallizes in the triclinic space group P1, whose structure comprises a 3D backbone made up of isolated [IO₃]^- pyramids and [MoO₄]^2- tetrahedra connected via 5- and 6-fold coordinated sodium cations. II crystallizes in the monoclinic space group P2₁/c and comprises isolated [MoO₂F₄]^2- octahedra with strong out-of-center distortions and the Na⁺ as well as Cs⁺ cations acting as interstitial ions. Both compounds have been characterized by infrared (IR) spectra and ultraviolet-visible-near-infrared (UV-vis-NIR) diffuse reflectance spectra. First-principles calculations respectively reveal that they exhibit birefringence values with Δn = 0.078 and 0.210 at 1064 nm for I and II, and the origin of the birefringence is discussed.

Four alkali metal molybdates with two types of Mo–O chains, ABMo3O10 (A = Li, B = Rb; A = Li, Na, K, B = Cs): synthesis, structure comparison and optical properties

The effects of cation size on the framework structures of four stoichiometrically equivalent alkali metal molybdates were discussed in detail.

Structural and magnetic studies on three new mixed metal copper(II) selenites and tellurites

Three new transition metal copper(II) selenites or tellurites, namely, CdCu(SeO3)2 (1), HgCu(SeO3)2 ()2, and Hg2Cu3(Te3O8)2 (3), have been obtained by conventional hydrothermal reactions of CdO (or Hg2Cl2), CuO and SeO2 (or TeO2). Compounds 1 and 2 are isostructural and crystallize in P2(1)/c. Their structures feature a 3D anionic framework of Cu(SeO3)2(2-) with 1D channels of eight-membered rings (MRs) along the c-axis and a-axis, respectively, which are filled by Cd(2+) or Hg(2+) cations. Compound 3 crystallizes in a tetragonal system of space group P42(1)2. Its structure is characterized by a [Cu3(Te3O8)2](2-) honeycomb layer composed of [Te3O8](4-) anions interconnected by Cu(2+) ions with 1D channels of 8-MRs along the c-axis. TOPOS analysis indicates that the copper(ii) tellurite layer exhibits a new topological structure with a Schläfli symbol of {4(6)·8(9)}(2){4(6)}(3). The above anionic copper(II) tellurite layers are further linked by dumbbell Hg2(2+) cations to form a novel 3D framework. Magnetic measurements based on magnetic susceptibility and heat capacity indicate that compounds 1 and 2 show a spin-singlet ground state with a spin gap based on the [Cu2O8](12-) dimeric model, whereas compound e3 xhibits a 2D spin-system with an antiferromagnetic ordering around 25 K correlated with its honeycomb [Cu3(Te3O8)2](2-) layer. Furthermore, crystalline structures, thermal stabilities, IR spectra and UV-Vis diffuse reflectance spectra have also been studied.

Effects of Te(IV) Oxo-Anion Incorporation into Thorium Molybdates and Tungstates

The exploration of phase formation in the Th-Mo/W-Te systems has resulted in four mixed oxo-anion compounds from high-temperature solid-state reactions: ThWTe2O9, Th(WO4)(TeO3), ThMoTe2O9, and Th2(MoO4)(TeO3)3. All four compounds contain edge-sharing thorium polyhedra linked by MoO4/WO6 and different tellurium oxo-groups to form three-dimensional frameworks. In ThWTe2O9, each helical Th based chain is connected by four tungstotellurite clusters resulting in a building fragment which has a cross-section of four-leafed clovers. The structure of Th(WO4)(TeO3) exhibits a multilayer-sandwich framework composed of thorium tellurite layers with tungsten chains in between. In the case of the molybdate family, ThMoTe2O9 and Th2(MoO4)(TeO3)3 are built from puckered Th-Te sheets which are further interconnected by MoO4 tetrahedral linkers. The DSC-TG technique was performed to gain insight into the thermal behavior of the synthesized compounds. Raman spectra of as-prepared phases were obtained and analyzed for signature peaks.

Explorations of new phases in the Ga(III)/In(III)-Cu(II)-Se(IV)-O system

Four new gallium(III)/indium(III), copper(II), selenium(IV) oxides, namely, Ga(2)Cu(SeO(3))(4) (1), Ga(2)CuO(SeO(3))(3) (2), and M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4), have been synthesized by hydrothermal or high-temperature solid-state reactions. The structure of Ga(2)Cu(SeO(3))(4) (1) features a 2D layer of corner-sharing GaO(6) and CuO(6) octahedra with the SeO(3) groups hanging on both sides of the 2D layer. Ga(2)CuO(SeO(3))(3) (2) features a pillared layered structure in which the 1D Cu(SeO(3))(3)(4-) chains act as the pillars between 2D layers formed by corner- and edge-sharing GaO(n) (n = 4, 5) polyhedra. Although the chemical compositions of M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4) are comparable, they belong to two different structural types. Ga(2)Cu(3)(SeO(3))(6) (3) exhibits a pillared layered structure built by [Ga(2)Cu(3)(SeO(3))(4)](4+) thick layers with Se(3)O(3)(2-) groups as pillars. The structure of In(2)Cu(3)(SeO(3))(6) (4) features a 3D network composed of [In(2)(SeO(3))(2)](2+) layers and [Cu(3)(SeO(3))(4)](2-) layers interconnected through Se-O-Cu and In-O-Cu bridges, exhibiting 8-MR helical tunnels along the a-axis. Results of magnetic property measurements indicate that there are considerable antiferromagnetic interactions between copper(II) centers in Ga(2)CuO(SeO(3))(3) (2) and M(2)Cu(3)(SeO(3))(6) (M = Ga 3, In 4). Interestingly, Ga(2)Cu(3)(SeO(3))(6) (3) behaves as a weak ferromagnet below the critical temperature of T(c) = 15 K. Further magnetic studies indicate that the compound is a canted antiferromagnet with a large canting angle of about 7.1 degrees.

Ni(3)(Mo(2)O(8))(XO(3)) (X = Se, Te): the first nickel selenite- and tellurite-containing Mo4 clusters

Two new nickel(II) molybdenum(VI) selenium(IV) and tellurium(IV) oxides generally formulated as Ni3(Mo2O8)(XO3) (X = Se, Te) have been synthesized by solid-state reactions of NiO, MoO3, and SeO2 (or TeO2). Both compounds feature 3D network structures built of [Mo4O16]8- tetranuclear cluster units and 2D nickel(II) selenite or tellurite layers. The nickel(II) selenite layer in Ni3(Mo2O8)(SeO3) is formed by [Ni6O22]32- hexanuclear clusters interconnected by selenite groups whereas the thick nickel(II) tellurite layer in Ni3(Mo2O8)(TeO3) is constructed by corrugated nickel(II) oxide chains bridged by the tellurite groups. The results of magnetic property measurements indicate that there are considerable ferromagnetic interactions between nickel(II) centers in both compounds. Their optical properties and band structures have been also studied.

New Luminescent Solids in the Ln−W(Mo)−Te−O−(Cl) Systems

Solid-state reactions of lanthanide(III) oxide (and/or lanthanide(III) oxychloride), MoO3 (or WO3), and TeO2 at high temperature lead to eight new luminescent compounds with four different types of structures, namely, Ln2(MoO4)(Te4O10) (Ln = Pr, Nd), La2(WO4)(Te3O7)2, Nd2W2Te2O13, and Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W). The structures of Ln2(MoO4)(Te4O10) (Ln = Pr, Nd) feature a 3D network in which the MoO4 tetrahedra serve as bridges between two lanthanide(III) tellurite layers. La2(WO4)(Te3O7)2 features a triple-layer structure built of a [La2WO4]4+ layer sandwiched between two Te3O72- anionic layers. The structure of Nd2W2Te2O13 is a 3D network in which the W2O108- dimers were inserted in the large tunnels of the neodymium(III) tellurites. The structures of Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W) feature a 3D network structure built of lanthanide(III) ions interconnected by bridging TeO32-, Te5O136-, and Cl- anions with the MO4 (M = Mo, W) tetrahedra capping on both sides of the Ln4 (Ln = Pr, Nd) clusters and the isolated Cl- anions occupying the large apertures of the structure. Luminescent studies indicate that Pr2(MoO4)(Te4O10) and Pr5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) are able to emit blue, green, and red light, whereas Nd2(MoO4)(Te4O10), Nd2W2Te2O13, and Nd5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) exhibit strong emission bands in the near-IR region.

Old materials with new tricks: multifunctional open-framework materials

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)

New Members in the Nin+1(QO3)nX2 Family: Unusual 3D Network Based on Ni4ClO3 Cubane-like Clusters in Ni7(TeO3)6Cl2

Three new members in the family of nickel(II) tellurium(IV)/selenium(IV) oxyhalides generally formulated as Ni(n+1)(QO3)nX2 (Q = Te, X = Cl, n = 6, 10; Q = Se, X = Br, n = 4) have been synthesized by solid-state reactions of NiX2, QO2, and NiO (or Ni2O3) at high temperature. The structure of Ni7(TeO3)6Cl2 features a novel 3D network based on Ni4ClO3 cubane-like clusters with Te atoms located at the cavities of the network. Ni4ClO3 clusters are interconnected into a hexagonal layer through additional O...O edges. The neighboring two layers are further interconnected, via sharing of common Ni(II) atoms, into a novel 3D network. The 3D open framework of Ni5(SeO3)4Br2 is built from 2D nickel(II) oxybromide layers bridged by Se and additional Ni atoms. The structure of Ni11(TeO3)10Cl2 features a condensed 3D network based on NiO5Cl, NiO6, and NiO5 polyhedra interconnected via corner and edge sharing, as well as O-Te-O bridges. The results of magnetic property measurements indicate that all three compounds display antiferromagnetic interactions between nickel(II) centers.