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Structural (XRD) and thermal (DSC, TGA) and BET analysis of materials derived from non-metal cation pentaborate salts

Structural (XRD) and thermal (DSC, TGA) and BET analysis of materials derived from non-metal cation pentaborate salts
Structural (XRD) and thermal (DSC, TGA) and BET analysis of materials derived from non-metal cation pentaborate salts
The synthesis, structural characterization (XRD), and thermal properties of nine non-metal cation (NMC) pentaborate anion salts, [NMC][B5O6(OH)(4)] (1a-1i) is described (NMC = [NH3CMe2(CH2OH)](+) (a), [O(CH2CH2)(2)NH2](+) (b), [NH3CMe(CH2OH)(2)](+) (c), [2-(2-CH2CH2OH)PyH](+) (d), [(CH2)(4)NH(CH2CH2OH)](+) (e), [(CH2)(5)NH(CH2CH2OH)](+) (f), [2-MeImid](+) (g), [Me3NCMe2(CH2OH)](+) (h), [O(CH2CH2)(2)NMe2](+) (i). Single-crystal X-ray diffraction studies on all compounds show that they contain isolated pentaborate anions, H-bonded together in a supramolecular array, with the cations occupying the cavities within the network. Compound 1c was obtained as a partial hydrate (0.16H(2)O). TGA and DSC analysis ( in air, 25-1000 degrees C) indicate that compounds 1a-1i thermally decompose via a 2 stage process to B2O3. The. first stage (<250 degrees C) is dehydration to condensed polymeric pentaborates {approximate composition: [NMC][B5O8] (2a-2i)}. Five condensed pentaborates (2a-c, 2e, 2g) were synthesised and characterized by powder XRD and BET analysis. These condensed pentaborates were amorphous. The isolated pentaborates intumesced at similar to 600 degrees C ( occupying similar to 10 times their original volume), and then contracted back to black glassy B2O3 solids at 1000 degrees C. The intumescent materials (3a), (3b), (3e), (3g), and a. final B2O3 sample (4b) were synthesised and isolated and their porosities determined. BET surface area analysis on the isolated pentaborates (1a-c, 1e, 1g), the condensed pentaborates (2a-c, 2e, 2g), intumesced materials (3a, 3b, 3e, 3g), and B2O3 (4b) showed that they were all 'non-porous' (<1.59 m(2) g(-1))
0300-9246
3944-3951
Beckett, Michael A.
5b021ef6-fa5c-4f6d-9998-3313558f0dc1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Knox, David A.
06c5c36d-b83c-466a-8767-5d2b30b939cb
Timmis, James L.
3bc450de-1482-49d1-8e75-3d957a989300
Beckett, Michael A.
5b021ef6-fa5c-4f6d-9998-3313558f0dc1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Knox, David A.
06c5c36d-b83c-466a-8767-5d2b30b939cb
Timmis, James L.
3bc450de-1482-49d1-8e75-3d957a989300

Beckett, Michael A., Horton, Peter N., Hursthouse, Michael B., Knox, David A. and Timmis, James L. (2010) Structural (XRD) and thermal (DSC, TGA) and BET analysis of materials derived from non-metal cation pentaborate salts. Dalton Transactions, 39 (16), 3944-3951. (doi:10.1039/b927072h). (PMID:20372719)

Record type: Article

Abstract

The synthesis, structural characterization (XRD), and thermal properties of nine non-metal cation (NMC) pentaborate anion salts, [NMC][B5O6(OH)(4)] (1a-1i) is described (NMC = [NH3CMe2(CH2OH)](+) (a), [O(CH2CH2)(2)NH2](+) (b), [NH3CMe(CH2OH)(2)](+) (c), [2-(2-CH2CH2OH)PyH](+) (d), [(CH2)(4)NH(CH2CH2OH)](+) (e), [(CH2)(5)NH(CH2CH2OH)](+) (f), [2-MeImid](+) (g), [Me3NCMe2(CH2OH)](+) (h), [O(CH2CH2)(2)NMe2](+) (i). Single-crystal X-ray diffraction studies on all compounds show that they contain isolated pentaborate anions, H-bonded together in a supramolecular array, with the cations occupying the cavities within the network. Compound 1c was obtained as a partial hydrate (0.16H(2)O). TGA and DSC analysis ( in air, 25-1000 degrees C) indicate that compounds 1a-1i thermally decompose via a 2 stage process to B2O3. The. first stage (<250 degrees C) is dehydration to condensed polymeric pentaborates {approximate composition: [NMC][B5O8] (2a-2i)}. Five condensed pentaborates (2a-c, 2e, 2g) were synthesised and characterized by powder XRD and BET analysis. These condensed pentaborates were amorphous. The isolated pentaborates intumesced at similar to 600 degrees C ( occupying similar to 10 times their original volume), and then contracted back to black glassy B2O3 solids at 1000 degrees C. The intumescent materials (3a), (3b), (3e), (3g), and a. final B2O3 sample (4b) were synthesised and isolated and their porosities determined. BET surface area analysis on the isolated pentaborates (1a-c, 1e, 1g), the condensed pentaborates (2a-c, 2e, 2g), intumesced materials (3a, 3b, 3e, 3g), and B2O3 (4b) showed that they were all 'non-porous' (<1.59 m(2) g(-1))

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e-pub ahead of print date: March 2010
Published date: April 2010
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow

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Local EPrints ID: 347468
URI: http://eprints.soton.ac.uk/id/eprint/347468
ISSN: 0300-9246
PURE UUID: 446aa3b2-3d8e-412b-827e-7d621b009702
ORCID for Peter N. Horton: ORCID iD orcid.org/0000-0001-8886-2016

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Date deposited: 23 Jan 2013 12:57
Last modified: 29 Oct 2019 01:57

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Contributors

Author: Michael A. Beckett
Author: Peter N. Horton ORCID iD
Author: David A. Knox
Author: James L. Timmis

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