Synthesis, Crystal Structure, and Spectrum Properties of a New Quaternary Borate NaSr7AlB18O36 with the Cyclic B18O36 18− Group, Notation of 6 × (3[2Δ + 1T])

Abstract

A new sodium strontium aluminoborate, NaSr 7 AlB 18 O 36 , has been synthesized by high-temperature solution reaction at 860°C. Its crystal structure was established by single-crystal X-ray diffraction technique: the space group R " 3c (No. 167), cell parameters a = 11.356(2) Å , c = 36.655 (7) Å , V = 4093.7(12) Å 3 , and Z = 6. It is isostructural with Sr 8 MgB 18 O 36 and the crystal structure consists of the cyclic B 18 O 36 18-building unit of corner-sharing twelve BO 3 triangles and six BO 4 tetrahedra. Each B 18 O 36 18-group is bonded to six octahedrally coordinated Al 3? centers via Al-O bonds to generate a 3D 3 1 [Al(B 18 O 36 )] 15-framework that has intersecting open channels occupied by Sr 2? /Na ? cations.The IR spectrum has further confirmed that the compound contains low symmetric BO 3 and BO 4 groups; UV-Vis diffuse reflectance spectrum revealed an optical band gap of about 3.65 eV; while solid-state fluorescence spectrum exhibited a broad emission band with the emitted main peak localized at about 533.3 nm and shoulder at 420 nm upon excitation by laser of 325 nm.

Identical in Formula but Not Isotypic in Configuration: Discovery of a New Highly Polymerized [B12O24] Cluster in Cs3AlB6O12

“…15 O 8 ] branches with an end-to-end model, and both types show identical formulas and structures. [13][14][15]21,22 Of course, the discovery of such borates greatly enriched the structural chemistry of the borate system.…”

“…In addition, borates containing isolated B–O/F groups usually have metal cations with strong covalence (like M = Zn, Be, Al, etc. ), in which the cations with a higher valence state can form rigid chemical bonds (M–O/F) and break the anionic framework into a 0D configuration because of their stronger coordination ability. , Among them, the low polymerization degree of isolated B m –O/F ( m < 6) groups, like [BO 2 ], [BO 3 ], [BO 4 ], [B 2 O 5 ], [B 3 O 6 ], and [B 5 O 10 ] units, is much more than that of the highly polymerized ones (∼97 vs 3%). ,− To date, the [B 18 O 36 ] cluster is the largest one in the anhydrous borates and is found in Sr 8 MB 18 O 36 (M = Mg, Zn, Cd) , and NaSr 7 AlB 18 O 36 series . Other highly polymerized 0D clusters B m -O/F ( m ≥ 6), like [B 6 O n ] ( n = 12, 14), [B 7 O 14 ], [B 9 O 21 ], [B 11 O 22 ], [B 12 O 24 ] units, etc., are also very limited and have only been discovered in few borates. − Studies have shown that the highly polymerized B–O clusters tend to form the same and certain configurations, like [B 12 O 24 ] and [B 18 O 36 ] units, in related compounds and are all in a cyclic formation constructed by [B 3 O 7 ] and [B 3 O 8 ] branches with an end-to-end model, and both types show identical formulas and structures. − ,, Of course, the discovery of such borates greatly enriched the structural chemistry of the borate system.…”

“…1,8−12 To date, the [B 18 O 36 ] cluster is the largest one in the anhydrous borates and is found in Sr 8 MB 18 O 36 (M = Mg, Zn, Cd) 13,14 and NaSr 7 AlB 18 O 36 series. 15 O 8 ] branches with an end-to-end model, and both types show identical formulas and structures. [13][14][15]21,22 Of course, the discovery of such borates greatly enriched the structural chemistry of the borate system.…”

Structural Insights into Borates with an Anion‐Templated Open‐Framework Configuration: Asymmetric K2BaB16O26 versus Centrosymmetric K3CsB20O32 and Na2M2NB18O30 (M=Rb, Cs; N=Ba, Pb)

“…With respect to borates featuring open‐framework configurations, aluminoborates and borogermanates constructed by polyhedral AlO n and GeO n building blocks, respectively, have been continuously reported, for example, PKU‐1 and PKU‐2 with channels formed of 18 and 24 octahedrally coordinated atoms. A new borogermanate, SU‐16, with intersecting 12‐ and 8‐membered rings channels has also been successfully synthesized under mild hydrothermal conditions and shows a novel zeolite framework topology with coordination sequences different from those of other zeolite frameworks.…”

Na8MB21O36 (M = Rb and Cs): Noncentrosymmetric Borates with Unprecedented [B21O36]9– Fundamental Building Blocks

“…Anhydrous Borates with High-Polymeric FBBs Sr 8 M(B 18 O 36 ) 15,32 18:[6(3:2Δ+T)] NaSr 7 Al(B 18 O 36 )33 …”