Aluminoborates with Open Frameworks: Syntheses, Structures, and Properties

Abstract

Five aluminoborates Al[B(5)O(10)] x H(2)dab x 2 H(2)O (1), [Al(B(4)O(9))(BO)] x H(2)en (2), [Al(B(4)O(9))(BO)] x H(2)dap (3), K(2)Al[B(5)O(10)] x 4 H(2)O (4), and (NH(4))(2)Al[B(5)O(10)] x 4 H(2)O (5) have been synthesized under hydrothermal conditions and characterized by means of elemental analysis, IR, TG analysis, MAS NMR, UV-vis and fluorescence spectroscopy, powder X-ray diffraction, single-crystal X-ray diffraction, and NLO determination. The structure 1 comprises of AlO(4) tetrahedra and B(5)O(10) clusters and contains 12-, 11-, and 8-MR 3D-intersecting channels with a CrB(4) topological net. Structures 2 and 3 are both constructed from the same AlB(5)O(13) clusters and exhibit a six-connected framework with 4(12)6(3) topology. Structures 4 and 5 are isomorphous and are composed of AlO(4) tetrahedra and B(5)O(10) clusters that possess odd 11-MR channels and 8-MR helical channels. Structures 2-5 crystallized in an acentric structure and presented good SHG properties. UV-vis spectral investigation indicates that they are wide-band-gap semiconductors. The electronic structure calculations for the compounds also have been performed.

A Series of Open‐Framework Aluminoborates Templated by Transition‐Metal Complexes

“…A similar phenomenon has also been observed in [AlA C H T U N G T R E N N U N G (B 4 O 9 )(BO)]·H 2 en, [13] in which the centrosymmetric en as a structure-directing agent (SDA) does not govern the acentric characteristic of the ABO framework. Therefore the chirality of complex cations as SDAs is only one of the important factors in making chiral/acentric materials.…”

“…In addition, AlA C H T U N G T R E N N U N G (iPrO) 3 rather than traditional Al 2 O 3 , AlCl 3 , or AlA C H T U N G T R E N N U N G (NO 3 ) 3 was employed as the Al source, mainly because the AlA C H T U N G T R E N N U N G (iPrO) 3 is easily dissolved in organic solvents, and the chiral Al center may form from three-coordinated AlA C H T U N G T R E N N U N G (iPrO) 3 that transforms into a four-coordinated AlO 4 group through the hydrolysis of Al-A C H T U N G T R E N N U N G (iPrO) 3 in the crystallization process, which will greatly increase the likelihood of producing acentric or chiral ABOs. [13] From the systematic exploration of the experimental conditions, the final products of the reaction systems are strongly dependent on pH value, reaction solvent, reaction temperature, and initial reactants. Although no single crystal of compound I d suitable for X-ray crystallographic analysis was made, its pure phase has been obtained and determined by X-ray powder diffraction (Figure 1).…”

“…[20] The B 5 O 10 5À unit (n = 0) as tetradentate bridging ligand coordinates to four metal centers, thereby generating a 3D open framework. [8, 12a,b, 13] Although the B 6 O 11 (OH) [20] [13] (NH 4 [13] [CH 3 [12a] and Al- [13] in which all building blocks contain a B 5 O 10 cluster. Compound III might be viewed as a derivative of compounds I a-d.…”

“…The combination of chiral AlO 4 groups and acentric B À O clusters results in the acentric characteristic of 3D ABO frameworks. [13] In II a-b, the asymmetric unit contains a unique transition-metal (M = Co, Ni) center. The N atoms of en ligands bonded to the M center occupy two split positions and have an occupancy of 0.5, which forms the rare trigonal prismatic geometry of the [M(en) 3 ] 2 + complex.…”

“…[7,12] More recently, we have successfully made a series of ABOs by using hydrothermal methods. [13] In these ABOs, the various shapes, sizes, and charges of protonated organic amines or inorganic cations have a significant structure-directing effect on the formation of the 3D ABO anionic frameworks.…”