From LiB₃O₅ to NaRbB₆O₉F₂: Fluorine‐Directed Evolution of Structural Chemistry

Abstract

Introducing fluorine into borates indicates the direction for structural evolution. A new fluorooxoborate, NaRbB O F featuring a unique [B O F ] layered structure and excellent optical properties has been synthesized. It is further demonstrated that incorporation of fluorine can enrich the structural chemistry of borates.

β‐CsB9O14: A Triple‐Layered Borate with Edge‐Sharing BO4 Tetrahedra Exhibiting a Short Cutoff Edge and a Large Birefringence

“…On the other hand, the crystal preparation method is also important. During the past few years, under vacuum‐sealed conditions, our group has synthesized some fluorooxoborates with unique structures, which increase the structural diversity of borates. Hence, guided by the above ideas, we carried out our research based on the Cs‐B‐O system using the vacuum‐sealed method to obtain structurally unique borates.…”

“…The IR spectrum was measured to specify the coordination of boron in β‐CsB 9 O 14 (Figure S4 in the Supporting Information). The IR spectrum exhibits the following absorption peaks, which were assigned by referring to the literature . The absorption peaks observed at 1435 and 1253 cm −1 arise from the modes of edge‐sharing BO 4 tetrahedra, which agree well with those of other reported borates .…”

NaRbB3O4F3: A New Fluorooxoborate with a Short UV Cutoff Edge Enriching the Structural Chemistry of Borate

“…It is clear that the reflectance has no obvious change from 175 to 300 nm, and its cutoff edge is below 175 nm, which indicates that NaRbB 3 O 4 F 3 may have potential application in the DUV optical areas. And its cutoff edge is comparable to that of other fluorooxoborates, such as, NaRbB 6 O 9 F 2 (<180 nm), [39] RbB 3 O 4 F 2 (<190 nm) [40] and so on [41] …”

“…In addition, the F atoms can also substitute O atoms of the [BO 4 ] groups forming [BO 3 F], [BO 2 F 2 ] or [BOF 3 ], [30] which can be considered as the preferred genes for designing novel optical functional crystals due to their large hyperpolarizability, polarizability anisotropy and the HUMO‐LUMO gap [31] . After much effort, several fluorooxoborates with various B−O−F frameworks and excellent properties have been reported, such as the promising candidates for deep‐UV nonlinear optical crystals AB 4 O 6 F (A=NH 4 , Na, Rb, Cs) [32–35] and MB 5 O 7 F 3 (M=Ca, Sr, Mg) series, [36–38] the birefringent crystals, NaRbB 6 O 9 F 2 , [39] RbB 3 O 4 F 2 , [40] and so on [41] . To date, the number of fluorooxoborates is relatively limited compared with the thousands of borates and there are still plenty of new fluorooxoborates to be explored, so how to design fluorooxoborates to extend the species and structural chemistry?…”

Pb2Al2B3O8F3: structure and properties of a new fluoroaluminoborate with non-traditional chain-like B3O8 groups

“…27 Moreover, [AlO m F n ] polyhedra have numerous coordination environments, allowing them to combine with other B–O anionic groups to provide more structural possibilities. 7,28,29 Then, a series of fluoroaluminoborates with excellent properties were designed and synthesized, such as SrAlB 3 O 6 F 2 with a special primitive group [Al 2 B 6 O 14 F 4 ] and RbAlB 3 O 6 F with prominent deep-ultraviolet nonlinear optical properties. 27,30 Therefore, it is valuable to continuously explore and design fluoroaluminoborates to enrich the borate structure chemistry.…”