Synthesis and Characterization of QD-3: The First Organically Templated Aluminoborate with 11-, 12-, and 14-Ring Intersecting Channels

Two Acentric Aluminoborates Incorporated d10 Cations: Syntheses, Structures, and Nonlinear Optical Properties

Two acentric aluminoborates (ABOs), [Zn(en)₂Al{B₅O₉(OH)}{BO(OH)₂}] (1) and [Cd(en)₂AlB₅O₁₀]·H₂O (2) (en = ethylenediamine), have been solvothermally made. 1 includes a two-dimensional (2D) wavy ABO layer using B₅O₉(OH) clusters and AlO₃{BO(OH)₂} groups, in which both units can be regarded as three-connected nodes, and simplifying the ABO layer to a hcb-type network. 2 features an acentric three-dimensional (3D) porous framework with a unique unc-type network constituted by strictly alternating connected B₅O₁₀ clusters and AlO₄ units. The structural transformation from a 2D layer 1 to a 3D framework 2 was achieved with the elimination of the terminal hydroxyls in layer 1 by adjusting synthetic conditions in the same solvent system. Metal-amine complexes Zn(en)₂/Cd(en)₂ bond to the inorganic walls and are located in the cavity of frameworks 1 and 2, respectively. Compounds 1 and 2 exhibit large second-harmonic generation (SHG) responses that are 2.2 and 2.7 times those of KH₂PO₄ (KDP), respectively, which are among the largest powder SHG responses for all deep-ultraviolet (deep-UV) ABOs. The UV-vis diffuse reflectance spectra of 1 and 2 show a wide transparency window below 190 nm. Density functional theory (DFT) calculations indicate that the B-O units and the introduced distorted d¹⁰ metal polyhedra played a decisive role in the optical properties of both compounds.

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).

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.

Trinuclear Cd3O14 hexaborate and two nickel borates based on molten salt synthesis and precursor synthesis: structure, characterization, and properties

In this work, different synthetic methods were used to prepare metal borates. One cadmium borate Cd3[B6O9(OH)2]2·2NO3·4H2O (1) and two nickel borate Ni0.8Mn0.2{B6O7(OH)3[O(CH2)2NH2]3} (2), [Ni(1-MI)6]·[B5O6(OH)4]2·2DMF (3, 1-MI = 1-methylimidazole, DMF = N,N-dimethylformamide) species were successfully prepared. The structures of these three compounds were confirmed via single crystal powder X-ray diffraction (SCPXRD), elemental analysis, FTIR, PXRD, and ICP studies. Compound 1 was prepared via molten salt synthesis, and compounds 2 and 3 were prepared via precursor synthesis, which is a synthetic method that uses a certain polyanionic cluster as a reagent. Compound 1 shows a novel three-dimensional (3D) structure, in which the [B6O11(OH)2] units acting as the basic polyanionic cluster form a two-dimensional (2D) anionic structure. In addition, the unexpected Cd3O14 clusters are connected with the 2D structures, leading to the 3D structure. The crystal structure of 2 is packed with very large neutral Ni0.8Mn0.2{B6O7(OH)3[O(CH2)2NH2]3} oxo-metal-boron clusters. The crystal structure of 3 consists of a [B5O6(OH)4]- cluster, a DMF molecule, and a [Ni(1-MI)6]2+ complex. In particular, 2 was successfully constructed using the same hexaborate cluster as its precursor. However, 3 only contains Ni2+ cations when a neutral NixMn1-x[B6O7(OH)6] cluster was used as an initial reagent, and it shows an ability to select a certain metal cation during the self-assembly process. Moreover, compounds 1, 2, and 3 exhibit different wide band gaps of 3.06 eV (1), 3.95 eV (2), and 4.24 eV (3).

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.

Na₂B₁₀O₁₇·H₂en: a three-dimensional open-framework layered borate co-templated by inorganic cations and organic amines

A layered borate Na2B10O17·H2en (1, en = ethylenediamine) with three-dimensional microporosity within the layers has been synthesized under solvothermal conditions by using organic amines and inorganic cations as the templates. Its framework displays a unique 5-connected net constructed by B5O11 cluster and emits blue luminescence.

Zn(1,3-DAP)[B4O7]: a rare chiral zeolitic framework constructed of four-connected [B4O9] clusters with a single-stranded helical channel

A zinc borate Zn(1,3-DAP)[B₄O₇] (1) was prepared. 1 possessed a rare chiral zeolitic framework based on a [B₄O₉] cluster. The combination of a [B₄O₉] cluster and Zn(1,3-DAP)O₃ chain produced a helical ribbon motif and gave rise to a single-stranded helical channel.

Series of open-framework aluminoborates containing [B5O10] clusters

Three new open-framework aluminoborates (ABOs), Rb₂AlB₅O₁₀·4H₂O (1), [C₅N₂H₁₆]AlB₅O₁₀ (2, C₅N₂H₁₆ = N-ethyl-1,3-diaminopropane) and [H₂dap][(CH₃)₂NH]AlB₅O₁₀ (3, dap = 1,2-diaminopropane) have been made under solvothermal conditions and characterized. The fluorescence and NLO properties were also studied.

Cotemplating synthesis of a rare borate Ni(en)3·Hen·[B9O13(OH)4]·H2O with a chiral polyanonic chain constructed from two different clusters

Ni(en)3·Hen·[B9O13(OH)4]·H2O was prepared under the cotemplating effect of [Ni(en)3](2+) and Hen(+). It was the first example of a cotemplated borate with an unusual chiral polyanionic chain, which was constructed from [B5O8(OH)2] and [B4O7(OH)2] clusters.

Systematic study of Cr3+ substitution into octahedra-based microporous aluminoborates

Single crystals of pure aluminoborate PKU-1 (Al3B6O11(OH)5·nH2O) were obtained, and the structure was redetermined by X-ray diffraction. There are three independent Al atoms in the R3 structure model, and Al3 locates in a quite distorted octahedral environment, which was evidenced by (27)Al NMR results. This distortion of Al3O6 octahedra release the strong static stress of the main framework and leads to a symmetry lowering from the previously reported R3 to the presently reported R3. We applied a pretreatment to prepare Al(3+)/Cr(3+) aqueous solutions; as a consecquence, a very high Cr(3+)-to-Al(3+) substitution content (∼50 atom %) in PKU-1 can be achieved, which is far more than enough for catalytic purposes. Additionally, the preference for Cr(3+) substitution at the Al1 and Al2 sites was observed in the Rietveld refinements of the powder X-ray data of PKU-1:0.32Cr(3+). We also systematically investigated the thermal behaviors of PKU-1:xCr(3+) (0 ≤ x ≤ 0.50) by thermogravimetric-differential scanning calorimetry, in situ high-temperature XRD in vacuum, and postannealing experiments in furnace. The main framework of Cr(3+)-substituted PKU-1 could be partially retained at 1100 °C in vacuum. When 0.04 ≤ x ≤ 0.20, PKU-1:xCr(3+) transferred to the PKU-5:xCr(3+) (Al4B6O15:xCr(3+)) structure at ∼750 °C by a 5 h annealing in air. Further elevating the temperature led to a decomposition into the mullite phase, Al4B2O9:xCr(3+). For x > 0.20 in PKU-1:xCr(3+), the heat treatment led to a composite of Cr(3+)-substituted PKU-5 and Cr2O3, so the doping upper limit of Cr(3+) in PKU-5 structure is around 20 atom %.

Incorporating [GaB4O11(OH)]8−clusters to construct luminescent galloborate with open-framework layers

A luminescent 5-connected galloborate with open-framework layers has been obtained under mild hydrothermal conditions by incorporating [GaB₄O₁₁(OH)]⁸⁻clusters.

Two Cu-complex directed aluminoborates: from 2D layers to 3D frameworks

Two novel aluminoborates (1 and 2) containing Cu complexes have been prepared under solvothermal conditions. Both are built from AlO₄ groups and [B₅O_10−n(OH)_n] (n = 0 and 2) clusters. 1 features a 2D aluminoborate layer with 16-member rings, whereas 2 is a 3D framework stacked by different building layers, showing the first Cu-complex directed aluminoborate.

A pillared–layered zincoborate with an anionic network containing unprecedented zinc oxide chains

The first pillared–layered 3D zincoborate framework built by Zn–O–B networks and 1,6-diaminohexane pillars, in which the {Zn₂} and {Zn₆} clusters linked alternately to form zigzag chains and joined by BO₃ units, resulting in 2D networks that were further decorated by B₃O₇H₂ clusters.

Synthesis and structure of QD-6: a novel aluminoborate constructed from unprecedented [B@Al6O24] and polyborate clusters

A novel aluminoborate (NH(4))(6)[C(5)NH(12)](6)[Al(12)B(65)O(105)(OH)(33)]·(H(2)O)(15) (QD-6), has been synthesized under mild hydrothermal conditions and characterized by IR, elemental analysis, TGA, powder and single-crystal X-ray diffractions. This compound crystallizes in the rhombohedral space group R3 (No. 148) with the lattice constants a = 23.7421(2) Å, c = 24.7699(3) Å, V = 12091.9(2) Å(3), and Z = 3. QD-6 consists of two unprecedented aluminoborate clusters, [Al(6)B(34)O(54)(OH)(18)](6-) and [Al(6)B(31)O(51)(OH)(15)](6-), which are built from the same hexagon-like [B@Al(6)O(24)] clusters and [B(11)O(17)(OH)(6)] or [B(10)O(16)(OH)(5)] polyborates.

Bis(ethylenediammonium) tetradecaborate

The title compound, 2C₂H₁₀N₂²⁺·B₁₄O₂₀(OH)₆⁴⁻, consists of a centrosymmetric tetra­deca­borate anion and two ethyl­enediammonium cations. The anions are inter­connected through strong O—H⋯O hydrogen bonds into a three-dimensional supra­molecular network with channels along [100], [010], [001] and [111]. The diprotonated cations reside in the channels and inter­act with the inorganic framework by extensive N—H⋯O hydrogen bonds.

Cyclo-hexyldimethyl-ammonium tetra-hydroxy-penta-borate

The title compound, [C(8)H(18)N](+)·[B(5)O(6)(OH)(4)](-), has been synthesized under mild solvothermal conditions in the presence of N,N-dimethyl-cyclo-hexyl-amine acting as a template. The structure consists of penta-borate [B(5)O(6)(OH)(4)](-) anions connected through O-H⋯O hydrogen bonds into a three-dimensional framework, with large channels along [100], [010] and [001] directions. The [C(8)H(18)N](+) cations reside in the channels, inter-acting with the framework through N-H⋯O hydrogen bonds.