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Beckett MA, Horton PN, Hursthouse MB, Timmis JL. Synthesis and Thermal Studies of Two Phosphonium Tetrahydroxidohexaoxidopentaborate(1-) Salts: Single-Crystal XRD Characterization of [ iPrPPh 3][B 5O 6(OH) 4]·3.5H 2O and [MePPh 3][B 5O 6(OH) 4]·B(OH) 3·0.5H 2O. Molecules 2023; 28:6867. [PMID: 37836710 PMCID: PMC10574587 DOI: 10.3390/molecules28196867] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/19/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
Two substituted phosphonium tetrahydoxidohexaoxidopentaborate(1-) salts, [iPrPPh3][B5O6(OH)4]·3.5H2O (1) and [MePPh3][B5O6(OH)4]·B(OH)3·0.5H2O (2), were prepared by templated self-assembly processes with good yields by crystallization from basic methanolic aqueous solutions primed with B(OH)3 and the appropriate phosphonium cation. Salts 1 and 2 were characterized by spectroscopic (NMR and IR) and thermal (TGA/DSC) analysis. Salts 1 and 2 were thermally decomposed in air at 800 °C to glassy solids via the anhydrous phosphonium polyborates that are formed at lower temperatures (<300 °C). BET analysis of the anhydrous and pyrolysed materials indicated they were non-porous with surface areas of 0.2-2.75 m2/g. Rhe recrystallization of 1 and 2 from aqueous solution afforded crystals suitable for single-crystal XRD analyses. The structure of 1 comprises alternating cationic/anionic layers with the H2O/pentaborate(1-) planes held together by H-bonds. The cationic planes have offset face-to-face (off) and vertex-to-face (vf) aromatic ring interactions with the iPr groups oriented towards the pentaborate(1-)/H2O layers. The anionic lattice in 2 is expanded by the inclusion of B(OH)3 molecules to accommodate the large cations; this results in the formation of a stacked pentaborate(1-)/B(OH)3 structure with channels occupied by the cations. The cations within the channels have vf, ef (edge-to-face), and off phenyl embraces. Both H-bonding and phenyl embrace interactions are important in stabilizing these two solid-state structures.
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Affiliation(s)
| | - Peter N. Horton
- Chemistry Department, University of Southampton, Southampton SO17 1BJ, UK
| | | | - James L. Timmis
- School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK
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Li JJ, Chen WF, Lan YZ, Cheng JW. Recent Progress in Crystalline Borates with Edge-Sharing BO 4 Tetrahedra. Molecules 2023; 28:5068. [PMID: 37446729 DOI: 10.3390/molecules28135068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/25/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Crystalline borates have received great attention due to their various structures and wide applications. For a long time, the corner-sharing B-O unit is considered a basic rule in borate structural chemistry. The Dy4B6O15 synthesized under high-pressure is the first oxoborate with edge-sharing [BO4] tetrahedra, while the KZnB3O6 is the first ambient pressure borate with the edge-sharing [BO4] tetrahedra. The edge-sharing connection modes greatly enrich the structural chemistry of borates and are expected to expand new applications in the future. In this review, we summarize the recent progress in crystalline borates with edge-sharing [BO4] tetrahedra. We discuss the synthesis, fundamental building blocks, structural features, and possible applications of these edge-sharing borates. Finally, we also discuss the future perspectives in this field.
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Affiliation(s)
- Jing-Jing Li
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Wei-Feng Chen
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - You-Zhao Lan
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
| | - Jian-Wen Cheng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China
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Beckett MA, Coles SJ, Horton PN, Rixon TA. Structural (XRD) Characterization and an Analysis of H-Bonding Motifs in Some Tetrahydroxidohexaoxidopentaborate(1-) Salts of N-Substituted Guanidinium Cations. Molecules 2023; 28:molecules28073273. [PMID: 37050036 PMCID: PMC10096507 DOI: 10.3390/molecules28073273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 04/14/2023] Open
Abstract
The synthesis and characterization of six new substituted guanidium tetrahydroxidohexaoxidopentaborate(1-) salts are reported: [C(NH2)2(NHMe)][B5O6(OH)4]·H2O (1), [C(NH2)2(NH{NH2})][B5O6(OH)4] (2), [C(NH2)2(NMe2)][B5O6(OH)4] (3), [C(NH2)(NMe2)2][B5O6(OH)4] (4), [C(NHMe)(NMe2)2][B5O6(OH)4]·B(OH)3 (5), and [TBDH][B5O6(OH)4] (6) (TBD = 1,5,7-triazabicyclo [4.4.0]dec-5-ene). Compounds 1-6 were prepared as crystalline salts from basic aqueous solution via self-assembly processes from B(OH)3 and the appropriate substituted cation. Compounds 1-6 were characterized by spectroscopic (NMR and IR) and by single-crystal XRD studies. A thermal (TGA) analysis on compounds 1-3 and 6 demonstrated that they thermally decomposed via a multistage process to B2O3 at >650 °C. The low temperature stage (<250 °C) was endothermic and corresponded to a loss of H2O. Reactant stoichiometry, solid-state packing, and H-bonding interactions are all important in assembling these structures. An analysis of H-bonding motifs in known unsubstituted guanidinium salts [C(NH2)3]2[B4O5(OH)4]·2H2O, [C(NH2)3][B5O6(OH)4]·H2O, and [C(NH2)3]3[B9O12(OH)6] and in compounds 1-6 revealed that two important H-bonding R22(8) motifs competed to stabilize the observed structures. The guanidinium cation formed charge-assisted pincer cation-anion H-bonded rings as a major motif in [C(NH2)3]2[B4O5(OH)4]·2H2O and [C(NH2)3]3[B9O12(OH)6], whereas the anion-anion ring motif was dominant in [C(NH2)3][B5O6(OH)4]·H2O and in compounds 1-6. This behaviour was consistent with the stoichiometry of the salt and packing effects also strongly influencing their solid-state structures.
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Affiliation(s)
- Michael A Beckett
- School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Simon J Coles
- Chemistry Department, University of Southampton, Southampton SO17 1BJ, UK
| | - Peter N Horton
- Chemistry Department, University of Southampton, Southampton SO17 1BJ, UK
| | - Thomas A Rixon
- School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
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Zinc Borate Hydrolysis. Molecules 2022; 27:molecules27185768. [PMID: 36144495 PMCID: PMC9501296 DOI: 10.3390/molecules27185768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 08/27/2022] [Accepted: 09/03/2022] [Indexed: 11/16/2022] Open
Abstract
The crystalline zinc borate phase ZnB3O4(OH)3, known in commerce as 2ZnO·3B2O3·3.5H2O, is an important industrial material used as a fire-retardant synergist in polymers, a source of micronutrients in agriculture, and a preservative in building materials. It lends durability to wood composite building materials by inhibiting attack by wood destroying organisms. The hydrolysis chemistry of this zinc borate is relevant to its industrial use. ZnB3O4(OH)3 exhibits incongruent solubility, reversibly hydrolyzing at neutral pH to insoluble Zn(OH)2 and soluble B(OH)3. It is sparingly soluble with a room temperature solubility of 0.270 wt% in terms of its equivalent oxide components in solution, comprising 0.0267 wt% B2O3 and 0.003 wt% ZnO. Aspects of the hydrolysis chemistry of zinc borate under neutral pH conditions are discussed.
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Altahan MA, Beckett MA, Coles SJ, Horton PN, Jones CL. Synthesis and characterization of a tertiary amine:boric acid (1:1) co-crystal and a neutral zwitterionic diamine pentaboron adduct. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Modification of Glass/Polyester Laminates with Flame Retardants. MATERIALS 2021; 14:ma14247901. [PMID: 34947505 PMCID: PMC8706711 DOI: 10.3390/ma14247901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/08/2021] [Accepted: 12/16/2021] [Indexed: 11/28/2022]
Abstract
This paper presents a review of flame retardants used for glass/polyester laminates. It concerns flame retardants withdrawn from use such as compounds containing halogen atoms and flame retardants currently used in the industry, such as inorganic hydroxides, phosphorus and nitrogen-containing compounds, antimony, and boron compounds, as well as tin–zinc compounds. Attention is also drawn to the use of nanoclays and the production of nanocomposites, intumescent flame retardant systems, and mats, as well as polyhedral oligomeric silsesquioxanes. The paper discusses the action mechanism of particular flame retardants and presents their advantages and disadvantages.
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Oxidoborates Templated by Cationic Nickel(II) Complexes and Self-Assembled from B(OH)3. INORGANICS 2021. [DOI: 10.3390/inorganics9090068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Several oxidoborates, self-assembled from B(OH)3 and templated by cationic Ni(II) coordination compounds, were synthesized by crystallization from aqueous solution. These include the ionic compounds trans-[Ni(NH3)4(H2O)2][B4O5(OH)4].H2O (1), s-[Ni(dien)2][B5O6(OH)4]2 (dien = N-(2-aminoethyl)-1,2-ethanediamine (2), trans-[Ni(dmen)2(H2O)2] [B5O6(OH)4]2.2H2O (dmen = N,N-dimethyl-1,2-diaminoethane) (3), [Ni(HEen)2][B5O6(OH)4]2 (HEen = N-(2-hydroxyethyl)-1,2-diaminoethane) (4), [Ni(AEN)][B5O6(OH)4].H2O (AEN = 1-(3-azapropyl) -2,4-dimethyl-1,5,8-triazaocta-2,4-dienato(1-)) (5), trans-[Ni(dach)2(H2O)2][Ni(dach)2] [B7O9(OH)5]2.4H2O (dach = 1,2-diaminocyclohexane) (6), and the neutral species trans-[Ni(en)(H2O)2{B6O7(OH)6}].H2O (7) (en = 1,2-diaminoethane), and [Ni(dmen)(H2O){B6O7(OH)6}].5H2O (8). Compounds 1–8 were characterized by single-crystal XRD studies and by IR spectroscopy and 2, 4–7 were also characterized by thermal (TGA/DSC) methods and powder XDR studies. The solid-state structures of all compounds show extensive stabilizing H-bond interactions, important for their formation, and also display a range of gross structural features: 1 has an insular tetraborate(2-) anion, 2–5 have insular pentaborate(1-) anions, 6 has an insular heptaborate(2-) anion (‘O+’ isomer), whilst 7 and 8 have hexaborate(2-) anions directly coordinated to their Ni(II) centers, as bidentate or tridentate ligands, respectively. The Ni(II) centers are either octahedral (1–4, 7, 8) or square-planar (5), and compound 6 has both octahedral and square-planar metal geometries present within the structure as a double salt. Magnetic susceptibility measurements were undertaken on all compounds.
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Xin SS, Zhou MH, Beckett MA, Pan CY. Recent Advances in Crystalline Oxidopolyborate Complexes of d-Block or p-Block Metals: Structural Aspects, Syntheses, and Physical Properties. Molecules 2021; 26:molecules26133815. [PMID: 34206683 PMCID: PMC8270256 DOI: 10.3390/molecules26133815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/02/2022] Open
Abstract
Crystalline materials containing hybrid inorganic–organic metal borates (complexes with oxidoborate ligands) display a variety of novel framework building blocks. The structural aspects of these hybrid metallaoxidoborates containing Cd(II), Co(II), Cu(II), Ga(III), In(III), Mn(II), Ni(II) or Zn(II) metal centers are discussed in this review. The review describes synthetic approaches to these hybrid materials, their physical properties, their spectroscopic properties and their potential applications.
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Affiliation(s)
- Shu-Sheng Xin
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China; (S.-S.X.); (M.-H.Z.)
| | - Ming-Hua Zhou
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China; (S.-S.X.); (M.-H.Z.)
| | - Michael A. Beckett
- School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK
- Correspondence: (M.A.B.); (C.-Y.P.)
| | - Chun-Yang Pan
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China; (S.-S.X.); (M.-H.Z.)
- Correspondence: (M.A.B.); (C.-Y.P.)
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The Flame Retardancy of Polyethylene Composites: From Fundamental Concepts to Nanocomposites. Molecules 2020; 25:molecules25215157. [PMID: 33167598 PMCID: PMC7664228 DOI: 10.3390/molecules25215157] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/25/2022] Open
Abstract
Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.
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Altahan MA, Beckett MA, Coles SJ, Horton PN. Oxidopolyborate chemistry: The self-assembled, templated, synthesis, and an XRD study of a 1-D coordination polymer, [Cu(en){B 6O 7(OH) 6}] .3H 2O (en = 1,2-diaminoethane). PHOSPHORUS SULFUR 2020. [DOI: 10.1080/10426507.2020.1804204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
| | | | - Simon J. Coles
- Faculty of Engineering and the Environment Chemistry, University of Southampton, Southampton, United Kingdom
| | - Peter N. Horton
- Faculty of Engineering and the Environment Chemistry, University of Southampton, Southampton, United Kingdom
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Synthesis and Structural Manipulation of a Polyanionic Zincoborate [Zn(H2O)6](NO3)2·[Zn{B3O3(OH)4}2(H2O)4]·2H2O by the Molten Salt Method and its Potential Application as a Flame Retardant. J CLUST SCI 2020. [DOI: 10.1007/s10876-020-01806-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Beckett MA, Meena BI, Rixon TA, Coles SJ, Horton PN. Pentaborate(1-) Salts and a Tetraborate(2-) Salt Derived from C 2- or C 3-Linked Bis(alkylammonium) Dications: Synthesis, Characterization, and Structural (XRD) Studies. MOLECULES (BASEL, SWITZERLAND) 2019; 25:molecules25010053. [PMID: 31877919 PMCID: PMC6982793 DOI: 10.3390/molecules25010053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 12/18/2019] [Accepted: 12/21/2019] [Indexed: 11/26/2022]
Abstract
The synthesis of a number of pentaborate(1-) salts from cations arising from N-substituted α,α-, α,β-, and α,γ-diaminoalkanes has been attempted in aqueous solution from B(OH)3 and the appropriate diammine in a 10:1 ratio. Despite relatively mild work-up conditions the pentaborate(1-) salts prepared were not always as anticipated and the following compounds were isolated in good yield: [Me2NH(CH2)2NHMe2][B5O6(OH)4]2 (1), [Et2NH(CH2)2NHEt2][B5O6(OH)4]2 (2), [Et2NH2][B5O6(OH)4] (3), [Me2NH2][B5O6(OH)4] (4), [Me2NH(CH2)3NHMe2][B5O6(OH)4]2 (5), [Et2NH(CH2)3NHEt2][B5O6(OH)4]2 (6), [Me3NCH2CH=CH2][B5O6(OH)4] (7), and [Me3N(CH2)3NMe3] [B5O6(OH)4]2.0.5H2O (8). The tetraborate(2-) salt, [Me3N(CH2)2NMe3][B4O5(OH)4].2B(OH)3.2H2O (9) was obtained in moderate yield (41%) from a 3:1 reaction of B(OH)3 with [Me3N(CH2)2NMe3](OH)2. All compounds were characterized by spectroscopy (1H, 11B, 13C NMR and IR) and thermal gravimetric analysis (TGA). BET analysis on materials derived thermally from selected samples (1, 2, 6, 7) all had porosities of < 1 m2/g, demonstrating that they were non-porous. Single-crystal XRD structures were obtained for 2, 3, 7, 8 and 9 and all contain extensive H-bonded polyborate lattices.
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Affiliation(s)
- Michael A. Beckett
- School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK; (B.I.M.); (T.A.R.)
- Correspondence: ; Tel.: +44-1248-382-378
| | - Bashdar I. Meena
- School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK; (B.I.M.); (T.A.R.)
| | - Thomas A. Rixon
- School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK; (B.I.M.); (T.A.R.)
| | - Simon J. Coles
- Chemistry Department, University of Southampton, Southampton SO17 1BJ, UK; (S.J.C.); (P.N.H.)
| | - Peter N. Horton
- Chemistry Department, University of Southampton, Southampton SO17 1BJ, UK; (S.J.C.); (P.N.H.)
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