Two novel metal borates with three-dimensional open-framework layers constructed from [M2B8O20(OH)2] (M = Al, Ga) cluster units

Three new aluminoborates: from 1D tube to 3D framework

Three new aluminoborates (ABOs) KCs[Al{B5O9(OH)}{BO(OH)2} (1), K0.5Cs[Al{B5O10}1/2{BO2(OH)}] (2), and Cs1.5[Al{B5O10}1/2{BO2(OH)}] (3) have been made under solvothermal conditions. 1 features a 1D tube constructed by the alternation of [B5O9(OH)]4- clusters and AlO4 units, onto which the [BO(OH)2]- triangles are grafted. To further construct higher dimensional structures based on the structure 1, solvents were adjusted for high basicity, resulting in the formations of the 3D ABO frameworks 2 and 3. 2 and 3 are isostructural and built from [B5O10]5- clusters, AlO4 tetrahedra and [BO2(OH)]2- triangles, in which [B5O10]5- clusters are bridged by AlO4 tetrahedra to produce a 2D ABO layer with 14-membered ring (MR) windows, and the [BO2(OH)]2- triangles act as the linkers to bridge the adjacent ABO layers to form 3D ABO frameworks containing eight types of channels. UV-vis diffuse reflectance spectra indicate that 1, 2, and 3 have potential applications in deep ultraviolet (DUV) regions.

Two layered galloborates from centric to acentric structures: syntheses and NLO properties

Two layered galloborates (GBOs), Na₃GaB₄O₉ (1) and Na₅Ga[B₇O₁₂(OH)]₂·2B(OH)₃ (2), have been solvothermally made. 1 exhibits an unprecedented layer built by GaO₄ tetrahedra and B₄O₉ clusters. 2 was made by raising the ratio of B/Ga and the reaction temperature of 1, featuring a 2D acentric layer built by GaO₄ groups and B₇O₁₃(OH) clusters. 2 shows the highest second-harmonic generation (SHG) response of 4.6 times that of KDP (KH₂PO₄) among main group metal borates (MBOs).

Synthesis and optical properties of N→Ga coordinated gallium boroxines

Reactions of the N,C,N-chelated organogallium amide LGa(NEt₂)₂ (1), where L is {2,6-(Me₂NCH₂)₂C₆H₃}^-, with organoboronic acids RB(OH)₂ yielded molecular gallium boroxines LGa(O₃B₂R₂) (2: R = OH, 3: R = Ph, 4: R = 4-MeO-C₆H₄, 5: R = 4-CHO-C₆H₄, 6: R = Fc), neutral analogues of gallaborates. The molecular structures revealed the presence of a six-membered central GaB₂O₃ ring. The film forming properties of 5 allowed the deposition of transparent thin films by a spin coating method. The thicknesses, refractive index, energy of the optical gap (Eoptg), activation energy of surface electrical conductivity (Esa) and pre-exponential factor (σ₀) of the thin layers of 5 were measured and they are close to those found for related oxygen glass. Finally, GBO 5 was also used as an additive to printing ink and a thin film of 5 was prepared by the gravure printing technique.

LiB9O15·H2dap·H2O: A Cotemplated Acentric Layer-Pillared Borate Built by Mixed Oxoboron Clusters

An acentric layer-pillared borate, LiB₉O₁₅·H₂dap·H₂O (1, dap = 1,3-diaminopropane), cotemplated by organic and inorganic cations and build by mixed oxoboron cluster units of B₆O₁₃^8- and B₃O₇^5-, has first been made under solvothermal conditions, in which the B₆O₁₃^8- clusters link each other to form 2D layers containing 9-membered ring (MR) windows, while the B₃O₇^5- clusters join together to produce 1D chains that further perform as the pillars to connect neighboring layers, resulting in a 3D layer-pillared framework with 13- and 7-MR channels located by H₂dap²⁺ and Li⁺ cations, respectively. Its second harmonic generation shows a response of ∼2.1 times that of KDP (KH₂PO₄).

From [B6O13]8− to [GaB5O13]8− to [Ga{B5O9(OH)}{BO(OH)2}]2−: synthesis, structure and nonlinear optical properties of new metal borates

By tuning the synthetic conditions, a 3D gallo-borate with a high second-harmonic generation response was obtained.

Three Inorganic-Organic Hybrid Gallo-/Alumino-Borates with Porous-Layered Structures Containing [MB4O10(OH)] (M = Al/Ga) Cluster Units

Three inorganic-organic hybrid gallo-/alumino-borates [Ga₂B₇O₁₄(OH)]·H₂dah (1, dah = 1,6-diaminohexane), K₂[Ga₂B₇O₁₄(OH)(en)_0.5] (2, en = ethylenediamine), and K₂[Al₂B₇O₁₄(OH)(en)_0.5]·H₂O (3) were synthesized under solvothermal conditions. Compound 1 features a 3D porous-layered structure built by the alternation of [GaB₄O₁₀(OH)]^6-, [B₃O₆]^3- clusters and GaO₄ tetrahedra, in which the novel [GaB₄O₁₀(OH)]^6- cluster is first observed. Compounds 2 and 3 are isostructural and made by [MB₄O₁₀(OH)]^6-, [B₃O₆(en)_0.5]^3- clusters and MO₄ tetrahedra (M = Ga/Al); their 3D porous layers are similar to those of 1 and further bridged by en linkers through the rare B-N-C covalent bonds, resulting in the 3D inorganic-organic hybrid framework. This is the first main-group metal borate with organic molecules participating in the oxoboron frameworks through B-N bonds. Optical diffuse-reflectance spectra reveal that 1, 2, and 3 are potential wide-band-gap semiconductors.

Syntheses and structures of a new 2D layered borate and a novel 3D porous-layered aluminoborate

Two new layered and porous-layered borates ([H₂dap][B₇O₁₁(OH)] (1, dap = 1,2-propanediamine) and [H₃O]K_3.52Na_3.48{Al₂[B₇O₁₃(OH)][B₅O₁₀][B₃O₅]}[CO₃] (2)) have been solvothermally made. 1 features a 2D layer made of the [B₇O₁₃(OH)]^6- cluster, in which H₂dap is located in the windows of the layers. The fundamental building block (FBB) [B₇O₁₃(OH)]^6- cluster in 1 represents a new type of FBB of the hepta-borate family. 2 is a novel aluminoborate with a 3D porous-layered structure formed by three types of oxoboron clusters, [B₇O₁₃(OH)]^6-, [B₅O₁₀]^5- and [B₃O₇]^5-, respectively. The strict alternation of the different oxoboron clusters and AlO₄ tetrahedra leads to the abundant channel systems of the structure. 2 is the first aluminoborate (ABO) containing three types of oxoboron clusters and the first 3D porous-layered ABO with seven types of channels. UV-vis diffuse reflectance spectra reveal that both of them are wide band-gap semiconductors and have potential applications in UV regions.

Two novel 3D borates: porous-layer and layer-pillar frameworks

Two new borates, NaK_1.5[B{B₅O₉(OH)}{B₅O₈(OH)₂}_1/2] (1) and Na_3.5[Al{B₃O₆(OH)}{B₅O₁₀}_1/2{BO(OH)}] (2), have been made by a solvothermal method. Structure 1 is made of two types of oxoboron clusters ([B₅O₉(OH)]^4- and [B₅O₈(OH)₂]^3-) and BO₄ tetrahedra to form a 3D porous layer, in which the [B₅O₉(OH)]^4- clusters are bridged by BO₄ groups to produce a 2D B-O layer with 11-membered ring (MR) windows, while the [B₅O₈(OH)₂]^3- clusters as 2-connected pillars join the adjacent B-O layers to make a 3-D porous layer. Structure 2 is built from two types of oxoboron clusters ([B₃O₆(OH)]^4- and [B₅O₁₂]^9-), AlO₄ units and BO₂(OH) triangles to produce 3D pillar-layered aluminoborate (ABO), in which the [B₅O₁₂]^9- clusters are linked together to form a 2-D B-O layer; the [B₃O₆(OH)]^4- clusters and AlO₄ groups join each other to form 1D tubular ABO; and the BO₂(OH) triangles act as linkers to connect the adjacent B-O layer and the ABO tubes, resulting in 3D pillar-layered ABO. Interestingly, the ABO tubes decorated with the BO₂(OH) triangles act as pillars to make a 3D layer-pillared structure. UV-vis diffuse spectra indicate that both have cut-off edges below 190 nm, and the calculated band gaps are 5.75 and 5.78 eV, respectively.

High-Temperature, High-Pressure Hydrothermal Synthesis, Crystal Structure, Thermal Stability, and Solid State NMR Spectroscopy of an Aluminum Borate, Ba[AlB4O8(OH)]

A new aluminum borate, Ba[AlB₄O₈(OH)], has been synthesized under high-temperature, high-pressure hydrothermal conditions at 550 °C and 1400 bar and its structure characterized by single-crystal X-ray diffraction, IR, and MAS ¹¹B, and ²⁷Al NMR spectroscopy. It crystallizes in the monoclinic space group P2₁/n with a = 7.0695(5) Å, b = 15.108(1) Å, c = 7.0746(5) Å, β = 93.593(2)°, and Z = 4. Its 2D layer structure is formed of corner-sharing B₄O₈(OH) clusters and AlO₄ tetrahedra with the charge-compensating Ba²⁺ cations between the layers. While the same in the framework composition, the title compound and the hydrate, Ba[AlB₄O₈(OH)]·H₂O, differ greatly in structure. Although the title compound contains an OH group, it is thermally stable up to 740 °C and then decomposes into Ba₂Al₂B₈O₁₇, as indicated by high-temperature DSC/TG analysis and powder X-ray diffraction.

Extending Unique 1D Borate Chains to 3D Frameworks by Introducing Metallic Nodes

Two novel alkali/alkaline-earth borates, Ba₆ [B₆ O₉ (OH)₆ ]₂ (H₃ BO₃ ) (1) and Li₇ MAlB₁₂ O₂₄ (M=Ba, Sr, Ca) (2 a-c), with 1D and 3D structures have been made hydrothermally and characterized. 1 features a rare 1D anionic chain built by hexaborate clusters of B₆ O₁₁ (OH)₆ ; each made of six BO₄ /BO₂ (OH)₂ tetrahedra. The anionic chains are embedded in the channels of a Ba₆ -based wheel-cluster open-framework. On the basis of the structural analyses of 1, by incorporating Al atoms as the linkers and tuning the reaction conditions, the novel anhydrous 3D aluminoborates (ABOs) 2 a-c have been successfully obtained, constructed from B₆ O₁₄ -based cluster chains and AlO₆ octahedra. The 3D ABO framework and 3D Ba-O-Li network are interpenetrated to give a final dense structure. The study not only realized the expansion of the structure from the 1D chain of 1 to the 3D dense ABOs 2 a-c, but also obtained the first 3D AlO₆ -containing ABOs made under hydrothermal conditions. Different from the previously known 4-connected zeolite-type ABOs, alternately arranged from AlO₄ tetrahedra and oxo-boron clusters, the AlO₆ octahedra in 2 a-c as the linkers join to six 1D B₆ O₁₄ -based cluster chains to produce 3D ABOs. The optical diffuse reflectance spectra reveal that 2 a-c have wide range transparency. In addition, the thermal property analysis proves that 2 a-c are congruently melting compounds and possess high thermostability.

β-BaGa[B4O8(OH)](H2O) and Ba4Ga[B10O18(OH)5](H2O): new barium galloborates featuring unusual [B4O8(OH)]5− and [B10O18(OH)5]11− clusters

Centrosymmetric β-BaGa[B₄O₈(OH)](H₂O) with a layered structure and polar Ba₄Ga[B₁₀O₁₈(OH)₅](H₂O) with a novel 3D framework structure have been reported.