Borates A Novel Twofold Interpenetrating 3D Diamondoid Borate Framework Constructed from B4and B5Clusters

Structural characterisation and optical properties of new alkaline earth phosphate CaMg(P4O12) and alkaline alumophosphate Cs3Al4(PO4)5

Two new family members of mixed alkali-earth metal phosphate and aluminophosphate CaMg(P4O12) and Cs3Al4(PO4)5 were prepared from a phosphate system using a high-temperature solution method. The structural analysis results show that two compounds crystallize in the monoclinic space group C2/c and P21/n and feature a three-dimensional (3D) network. The 3D structure of CaMg(P4O12) consists of [CaO6], [MgO6] octahedra and [P4O12] rings, in which the [MgO6] and [P4O12] rings link to form a 3D structure and Ca2+ cations are filled within the structure. Interestingly, for compound Cs3Al4(PO4)5, its structure features 4, 8, and 12-ring channels with [Al2O4O4P2O4], [Al4O8O8P4O8] and [Al6O12O12P6O12] units as BBUs, respectively; the Cs+ cations are located in the cavities. Furthermore, IR spectral analysis and thermal properties are discussed. UV-vis-NIR diffuse reflectance spectroscopy data show that the UV cutoff edges of CaMg(P4O12) are below 200 nm. Remarkably, in order to determine optical properties and the structure-properties relationship, theoretical calculations were adopted. Electronic structure calculations demonstrate that CaMg(P4O12) has an indirect band gap with the value of 5.86 eV, and Cs3Al4(PO4)5 has a direct band gap of 5.21 eV.

Crystal structure of MgK0.5[B6O10](OH)0.5·0.5H2O, poly[dimagnesium potassium bis(hexa-borate) hy-droxide monohydrate]

The solvothermal reaction of H3BO3, KCF3SO3, Mg(CF3SO3)2 and pyridine led to a new alkali- and alkaline-earth-metal borate, MgK0.5[B6O10](OH)0.5·0.5H2O. Its structure features an intricate three-dimensional framework built from [B6O13]8- clusters, thus resulting in a six-connected achiral net with high symmetry. Each [B6O13]8- building block is composed of three trigonal BO3 and three tetra-hedral BO4 units, with these BO4 units being further connected to neighboring BO3 units, giving rise to an oxoboron cluster of the general formula [B6O10]2-.

Two New Nonaborates with {B9} Cluster Open-Frameworks and Short Cutoff Edges

Two new nonaborates, Na₂Ba_0.5[B₉O₁₅]·H₂O (1) and Na₄Ca_1.5[B₉O₁₆(OH)₂] (2), have been solvothermally made with mixed alkali and alkaline-earth metal cationic templates. 1 and 2 are constructed by two different types of nonaborate clusters. In 1, the [B₉O₁₉]¹¹⁻ cluster is composed of three corner-sharing [B₃O₇]⁵⁻ clusters, of which two of them interconnect to the 1D B₃O₇-based chains and are further bridged to the 3D framework with 7 types of 10-MR channels by another [B₃O₇]⁵⁻ bridging cluster. The [B₉O₁₈(OH)₂]¹¹⁻ cluster in 2 is made of four BO₄-sharing [B₃O₈]⁷⁻ clusters. As a 4-connected node, the interconnections of [B₉O₁₈(OH)₂]¹¹⁻ construct the unpreceded 2D layer with large 14-MR windows, which are further joined by H-bonds to the 3D supramolecular framework. UV–Vis absorption spectra reveal that both 1 and 2 have short cutoff edges below 190 nm, exhibiting bandgaps of 6.31 and 6.39 eV, respectively, indicating their potential applications in deep UV (DUV) regions.

MM'B3O4F3 (M = K; M' = Na, K, Cs): Alkali-Metal Fluorooxoborates with ∞1[B3O4F3] Chains and Deep-Ultraviolet Cutoff Edges

Three mixed-alkali-metal fluorooxoborates, KNaB₃O₄F₃ (I), K₂B₃O₄F₃ (II), and KCsB₃O₄F₃ (III), were acquired in a closed system. I-III are isomorphic and adopt orthorhombic structures [Pbcn (No. 60)] with wavy parallelly arranged pseudolayers composed of _∞¹[B₃O₄F₃] chains, which exhibit slight differences in the arrangement modes of the fundamental building blocks. First-principles calculations illustrate that they all have moderate birefringence and large band gaps on the order of 7.0 eV, suggesting deep-ultraviolet (DUV) cutoff edges. In order to investigate the main source of the optical properties, the electronic structure and anisotropy of the response electron distribution were analyzed. Experimental characterizations for I confirm the structure and DUV transparence ability.

Syntheses, structures and optical properties of two B3O7 cluster-based borates

1 is a 2D fluctuant layered borate made from two different B3O7 clusters. 2 features a 3D open framework with large 17-MR channels filled with Li-BO(OH)2-Ca chains.

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).

K2 Na3 [{B6 O10 (OH)}{B3 O4 (OH)3 }] ⋅ H2 O: A Layered Borate Built by Mixed Oxoboron Clusters with Nonlinear-Optical Property

A new acentric borate, K₂ Na₃ [{B₆ O₁₀ (OH)}-{B₃ O₄ (OH)₃ }] ⋅ H₂ O (1) has been made under solvothermal condition. 1 has layered structure made by B₆ O₁₃ (OH)-based chains and B₃ O₅ (OH)₃ -bridging clusters. Second-harmonic generation (SHG) measurements reveal that 1 is a phase-matchable nonlinear optical (NLO) material, showing the SHG signal intensity of 1.8 times that of KDP (KH₂ PO₄ ). Besides, UV-Vis diffuse reflectance spectrum shows that 1 has the short deep UV (DUV) absorption cutoff edge of 198 nm. Thermogravimetric analysis reveals it has good thermal stability. Also 1 represents firstly mixed oxoboron clusters-made 2D layered borate with NLO property.

Two Chiral Metal Complex Templated Aluminoborates Constructed from Three Types of Oxoboron Clusters

The two acentric aluminoborates (ABOs) [M(dap)₃]₂{Al[B₅O₇(OH)₃][B₅O₈(OH)₂][B₆O₉(OH)₂]} (M and dap represent Co(1)/Ni(2) and 1,2-diaminopropane, respectively) templated by chiral metal complexes (CMCs) have been solvothermally synthesized. The isostructural 1 and 2 crystallize in the chiral space group P2₁. Both feature unprecedented 2D wavelike layers built by three kinds of oxoboron (B-O) clusters ([B₅O₇(OH)₃]^2-, [B₅O₈(OH)₂]^3-, and [B₆O₉(OH)₂]^2-) and AlO₄ tetrahedra. In the frameworks of 1 and 2, AlO₄ and [B₆O₉(OH)₂]^2- units are strictly alternating into 1D chains. Further, [B₅O₈(OH)₂]^3- clusters link adjacent chains to form 2D wavelike layers. In addition, the [B₅O₇(OH)₃]^2- units as the hanging clusters are supported on two sides of the wavelike layers through AlO₄ groups, resulting in the first example of a wavelike layer ABO composed of three kinds of B-O clusters and four types of channels. 1 and 2 display second-harmonic generation (SHG) signals about ∼1.3 and ∼0.93 times that of KH₂PO₄ (KDP) and belong to the class of wide-band-gap semiconductors.

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.