Abstract:The crystal structure of synthetic nasinite, Na2[BsOa(OH)].2H20, has been determined and refined from 1320 single-crystal diffractometer data by means of direct methods and least-squares refinement with anisotropic thermal parameters (isotropic for hydrogen atoms), giving R = 0.027. Hydrogen atoms were located on a AF map. Lattice constants determined on the same diffractometer are: a= 12.015 (2), b=6-518 (I), c= 11"173 (1)/~; space group Pna2x; Z=4. The structure is dominated by sheets in the be plane, result… Show more
“…The [CeB 5 O 9 ] layer can also be described by [B 5 O 11 ] as a FBB (5∞ 2 :(3Δ + 2T)) as shown in Figure b. This is also a common borate unit found in other borates, such as nasinite (Na 2 [B 5 O 8 (OH)]·2H 2 O), which contains a similar Na[B 5 O 9 ] layer, but additional Na ions are present between the layers so as to compensate for the negative charge. 6 (a) An overview of structure of Ce[B 5 O 8 (OH)]NO 3 ·3H 2 O projected along the a -axis.…”
Three novel hydrated rare earth polyborates, Ln[B8O11(OH)5] (Ln = La−Nd) (1), Ln[B9O13(OH)4]·H2O (Ln = Pr − Eu) (2), and Ce[B5O8(OH)]NO3·3H2O (3) have been synthesized by
using boric acid as a flux at 240 °C, starting from rare earth oxides or nitrates and an excess
of boric acid. All these polyborates crystallize in monoclinic structures (P21/n) and consist of
borate sheets as the fundamental unit, that is, [LnB6O11] sheet in 1 and 2 and [CeB5O9]
sheet in 3. The borate sheets all contain a nine-membered borate ring, of which the rare
earth cations are located around the center. The borate frameworks in 1 and 3 are two-dimensional, which are interlinked via ionic Ln−O bonds forming 3D structures. While in
2 the borate framework is three-dimensional with small channels filled by water molecules.
Annealing the hydrated polyborates 1 and 2 at moderate temperature leads to two anhydrous
pentaborates, α-LnB5O9 (4) for Ln = Pr−Eu and β-LnB5O9 (5) for Ln = La, Ce. The structure
of β-LaB5O9 has been determined by an ab initio method using powder X-ray diffraction
data. It crystallizes in a monoclinic structure in the space group P21/c with a = 6.4418(1) Å,
b = 11.6888(3) Å, c = 8.1706(2) Å, and β = 105.167(1)°. The structure of β-LnB5O9 contains
buckled nine-membered ring borate sheets that are interlinked by BO3 groups forming a
three-dimensional framework. The Eu3+-doped β-LaB5O9 materials show dominant 5D0 →
7F2 emission and a low quenching concentration (0.6 at. %).
“…The [CeB 5 O 9 ] layer can also be described by [B 5 O 11 ] as a FBB (5∞ 2 :(3Δ + 2T)) as shown in Figure b. This is also a common borate unit found in other borates, such as nasinite (Na 2 [B 5 O 8 (OH)]·2H 2 O), which contains a similar Na[B 5 O 9 ] layer, but additional Na ions are present between the layers so as to compensate for the negative charge. 6 (a) An overview of structure of Ce[B 5 O 8 (OH)]NO 3 ·3H 2 O projected along the a -axis.…”
Three novel hydrated rare earth polyborates, Ln[B8O11(OH)5] (Ln = La−Nd) (1), Ln[B9O13(OH)4]·H2O (Ln = Pr − Eu) (2), and Ce[B5O8(OH)]NO3·3H2O (3) have been synthesized by
using boric acid as a flux at 240 °C, starting from rare earth oxides or nitrates and an excess
of boric acid. All these polyborates crystallize in monoclinic structures (P21/n) and consist of
borate sheets as the fundamental unit, that is, [LnB6O11] sheet in 1 and 2 and [CeB5O9]
sheet in 3. The borate sheets all contain a nine-membered borate ring, of which the rare
earth cations are located around the center. The borate frameworks in 1 and 3 are two-dimensional, which are interlinked via ionic Ln−O bonds forming 3D structures. While in
2 the borate framework is three-dimensional with small channels filled by water molecules.
Annealing the hydrated polyborates 1 and 2 at moderate temperature leads to two anhydrous
pentaborates, α-LnB5O9 (4) for Ln = Pr−Eu and β-LnB5O9 (5) for Ln = La, Ce. The structure
of β-LaB5O9 has been determined by an ab initio method using powder X-ray diffraction
data. It crystallizes in a monoclinic structure in the space group P21/c with a = 6.4418(1) Å,
b = 11.6888(3) Å, c = 8.1706(2) Å, and β = 105.167(1)°. The structure of β-LnB5O9 contains
buckled nine-membered ring borate sheets that are interlinked by BO3 groups forming a
three-dimensional framework. The Eu3+-doped β-LaB5O9 materials show dominant 5D0 →
7F2 emission and a low quenching concentration (0.6 at. %).
“…All of these borate anions form hydrogen-bonded supramolecular frameworks that serve as hosts for alkyldiammonium cations, [H 3 N(CH 2 ) n NH 3 ] 2+ (n ) 5-12), and these 10 The first two compounds contain isolated tetraborate anions, whereas the third has a covalent borate sheet structure similar to that found in the mineral nasinite, Na[B 8 O 10 (OH)]‚2H 2 O, also known as Auger's borate. 11 It should also be noted that diamine and long-chain polyamine borates have been exploited as templates in the synthesis of porous tectosilicates. 12…”
Section: Introductionmentioning
confidence: 99%
“…Relevant previously described borates derived from diaminoalkanes include [H 3 N(CH 2 ) 2 NH 3 ][B 4 O 5 (OH) 4 ] from 1,2-diaminoethane and two “organically templated” borates, [H 3 N(C 6 H 10 )NH 3 ][B 4 O 5 (OH) 4 ] and [H 3 N(C 6 H 10 )NH 3 ][B 5 O 8 (OH)], from trans -1,4-diaminocyclohexane . The first two compounds contain isolated tetraborate anions, whereas the third has a covalent borate sheet structure similar to that found in the mineral nasinite, Na[B 8 O 10 (OH)]·2H 2 O, also known as Auger's borate . It should also be noted that diamine and long-chain polyamine borates have been exploited as templates in the synthesis of porous tectosilicates …”
A series of crystalline nonmetal borate compounds was prepared by reactions of linear α,ω-diaminoalkanes, H2N(CH2)
n
NH2 (n = 5−12), with excess boric acid in aqueous solution. These simple reagents self-assemble in water to form complex
ordered structures. The products were characterized by a combination of elemental, thermal, and X-ray diffraction analyses as well
as single-crystal X-ray diffraction studies. In each case except for n = 7 and 12, a bis(pentaborate) product of general formula
[H3N(CH2)
n
NH3][B5O6(OH)4]2 (1, 2, 4−7) was obtained in good yield. When n = 12, the product, [H3N(CH2)12NH3][B5O6(OH)4]2·4H2O (8), contained interstitial water. When n = 7, a product of composition [H3N(CH2)
7
NH3][B8O10(OH)6]·2B(OH)3 (3) was
obtained, containing an unusual octaborate anion and interstitial boric acid. The borate anions form hydrogen-bonded supramolecular
anionic frameworks that host alkyldiammonium dications. These cations contribute to hydrogen bonding and arrange either extended
linearly or folded to varying degrees across channels. This study reveals an interplay between the anionic borate host and the
cationic guest in which the nature of the cation controls the borate framework structure, which in turn influences cation conformation.
“…Several phase had been obtained in the Na 2 O-B 2 O 3 -H 2 O system under hydrothermal conditions [3]. In this paper, we describe the syntheses and structural characterization of new hydrated sodium borate of Na 4 [B 10 O 16 (OH) 2 ]·4H 2 O and the difference with nasinite [3]. * Corresponding author.…”
Section: Introductionmentioning
confidence: 99%
“…These BO 3 and BO 4 groups may further link together via common oxygen atoms to form isolated rings and cages or polymerize into infinite chains, sheets and networks. Several phase had been obtained in the Na 2 O-B 2 O 3 -H 2 O system under hydrothermal conditions [3]. In this paper, we describe the syntheses and structural characterization of new hydrated sodium borate of Na 4 [B 10 O 16 (OH) 2 ]·4H 2 O and the difference with nasinite [3].…”
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