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

Abstract

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.

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

“…[45][46][47][48] However, the coexistence of {B 5 } cluster and [BO n (OH) 3−n ] n− is rare among the known ABOs. To date, only a few examples as follows: [(C 6 H 18 N 2 ) (AlB 6 O 13 H 3 )] (4), 49 [Zn(en) 2 Al{B 5 O 9 (OH)}{BO(OH) 2 }] (5), 50 [M (dien) 2 ][AlB 6 O 11 -(OH)] (M = Co, Ni, Cd, Zn) (6). 51 The number of terminal hydroxyls and the difference in the linking modes result in various structures.…”

From Layered Borate to Porous-Layered Aluminoborate

“…Al 3+ /Ga 3+ ions exhibit similar outer electronic configurations with B 3+ and larger ionic radii, which can coordinate with oxygen atoms to form tetrahedral MO 4 , triangular–bipyramidal MO 5 , and octahedral MO 6 (M = Al/Ga). By introducing Al/Ga as framework heteroatoms into the B–O system, it is possible to make ABOs/galloborates (GBOs) optical materials with wide UV/deep UV transparency by eliminating the hydroxyl group on the isolated B–O clusters and further enhance the structural novelty of the B–O system. − Since 2009, our group first proposed introducing an organic Al source (aluminum isopropoxide, Al­(i-PrO) 3 ) instead of the traditional inorganic Al source in the hydro-/solvothermal synthetic system and made a series of ABOs by amines or metal–amine complexes as the templates . On this basis of the ongoing works, ABOs and GBOs templated by alkali/alkaline earth metals are further explored, for instance, Ba 3 M 2 [B 3 O 6 (OH)] 2 [B 4 O 7 (OH) 2 ] (M = Al/Ga) contains a layer-pillar built by the Al­(Ga)­O 4 –B 3 O 6 (OH) layers and the B 4 O 7 (OH) 2 cluster pillars; Ba­[MB 4 O 8 (OH)]·H 2 O (M = Al/Ga) includes bilayers consisted by B 4 O 8 (OH) units and M 2 O 8 dimers (M = Al/Ga); and Li 7 MAlB 12 O 24 (M = Ba/Sr/Ca) contains a 3D ABO framework built by AlO 6 octahedra and B 6 O 14 -based chains .…”

Recent Progress in Crystalline Borates with Edge-Sharing BO4 Tetrahedra

“…Borates show rich structural chemistry and have broad applications as birefringent materials and nonlinear optical (NLO) materials [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The famous KBe 2 BO 3 F 2 (KBBF), LiB 3 O 5 (LBO), and β -BaB 2 O 4 ( β -BBO) crystals are used to generate ultraviolet (UV) or deep-UV lasers through cascaded frequency conversion in practical application [ 32 , 33 , 34 ].…”