The Preparation of a New Boron Hydride B18H22

Pitochelli, Anthony R.; Hawthorne, M. Frederick

doi:10.1021/ja00875a058

Cited by 65 publications

(43 citation statements)

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“…Anti-B 18 H 22 was synthesized by the iodine oxidation of the [B 9 H 12 ] À anion according to the method described in the literature 39 . Pure samples were obtained by repeated crystallizations from hot saturated n-hexane solutions, followed by sublimation under vacuum at 135°C, and had 11 B and 1 H NMR and mass spectroscopic characteristics in agreement with the published data 21,40 . The resulting crystalline powder is readily soluble in organic non-polar aprotic solvents (for example, cyclohexane) and can thus be handled experimentally in an analogous way to that of well-known organic dyes.…”

Section: Methodssupporting

confidence: 73%

“…Of all the known binary boranes (compounds consisting only of boron and hydrogen), anti-B 18 H 22 is the only one to have the property of fluorescence. This attribute was first noticed by Hawthorne et al 21 , and yet only recently described comprehensively, including a full consideration of all transitions between ground and excited electronic states of the molecule 22 . In this latter study, anti-B 18 H 22 was revealed to exhibit an intense blue fluorescence at 407 nm ( Fig.…”

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confidence: 86%

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A borane laser

et al. 2015

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Emission from electronically excited species forms the basis for an important class of light sources-lasers. So far, commercially available solution-processed blue-emitting laser materials are based on organic compounds or semiconductor nanocrystals that have significant limitations: either low solubility, low chemical-and/or photo-stability and/or uncompetitive prices. Here we report a novel and competitive alternative to these existing laser materials that is based on boron hydrides, inorganic cluster compounds with a rich and diverse chemistry. We demonstrate that solutions of the borane anti-B 18 H 22 show, under pulsed excitation, blue laser emission at 406 nm with an efficiency (ratio of output/input energies) of 9.5%, and a photostability superior to many of the commercially available state-of-the-art blue laser dyes. This demonstration opens the doors for the development of a whole new class of laser materials based on a previously untapped resource for laser technology-the boranes.

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Section: Methodssupporting

confidence: 73%

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confidence: 86%

A borane laser

et al. 2015

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“…12 By itself, however, ortho-carborane shows no photoluminescence in solution 13 and just a blue-green phosphorescence in the solid-state at temperatures of 77 K. 13 Indeed, of all the known binary boranes (compounds consisting only of boron and hydrogen), anti-B18H22 -the centrosymmetric isomer of octadecaborane (22) -is the only one known to have the property of fluorescence. This attribute was first noticed by Hawthorne et al some years ago, 14 and subsequently described comprehensively, including a full consideration of all transitions between ground and excited electronic states of the molecule. 15 In this latter study, anti-B18H22 was revealed to exhibit an intense blue fluorescence at 406 nm with a quantum yield approaching unity (ΦF = 0.97).…”

Section: Introductionmentioning

confidence: 89%

Substitution of the laser borane anti-B₁₈H₂₂ with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron hydrides

et al. 2018

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Reaction of anti-BH1 with pyridine in neutral solvents gives sparingly soluble BH-3',8'-Py3a as the major product (ca. 53%) and BH-6',9'-Py2 (ca. 15%) as the minor product, with small quantities of BH-8'-Py 4 (ca. 1%) also being formed. The three new compounds 2, 3a and 4 are characterized by single-crystal X-ray diffraction analyses and by multinuclear multiple-resonance NMR spectroscopy. Compound 2 is of ten-vertex nido:ten-vertex arachno two-atoms-in-common architecture, long postulated for a species with borons-only cluster constitution, but previously elusive. Compound 3a is of unprecedented ten-vertex nido:eight-vertex arachno two-atoms-in-common architecture. The single-crystal X-ray diffraction analysis for the picoline derivative BH(NCHMe)3b, similarly obtained, is also presented. BHPy 4 is also previously unreported but is of known ten-vertex nido:ten-vertex nido two-atoms-in-common architecture of anti configuration, but now with the pyridine ligand positioned differently to other reported examples of BHL compounds. Factors behind the remarkably low solubility of 3a and 3b are elucidated in terms of electrostatic potential (ESP) calculations, polarity, and van der Waals complementarities. In view of contemporary developing high interest in the fluorescent properties of macropolyhedral boron-containing species, a detailed assessment of the photophysical characteristics of 3a and 4 is also presented. In contrast to the thermochromic fluorescence of 2 (from 620 nm brick-red at room temperature to 585 nm yellow at 8 K, quantum yield 0.15), compound 3a is only weakly phosphorescent in the yellow region (590 nm, quantum yield 0.01), whereas compound 4 exhibits no luminescence. The far more photoactive nature of compound 2 is associated with S excited-state minima structures that differ from each other only by the relative rotational positions of the pyridine substituents on its disubstituted ten-vertex {arachno-BPy}-subcluster. The wavelength and relative intensity of fluorescence from these structures depends on the rotational positions of the pyridine ligands, which in turn are influenced by temperature and/or rotational inhibition in the solid-state.

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“…To date, two isomers of the binary borane B 18 At this point it is noted that, since the initial report of the synthesis and the description of absorption bands of both of these isomers, 33 it has been known that anti-B 18 H 22 1 fluoresces but syn-B 18 H 22 2 does not; the two isomers therefore have distinctly different photophysical properties, and we have recently elucidated the origins of this interesting natural phenomenon by means of high-level quantum-chemical computations. 32 From a consideration of the two-dimensional (2D) 'unfolded' projections from Figure 2, it is reasonable to speculate an extension of the B 18 H 22 structural principle by the addition of further pentagonal pyramids, using the two central fused pentagonal pyramids as a starting structure, as represented schematically in Figure 3.…”

Section: New Isomers Derived From B 18 H 22mentioning

confidence: 99%

Borane Polyhedra as Building Blocks for Unknown but Potentially Isolatable New Molecules – Extensions based on Computations of the Known B18H22 Isomers

Oliva¹,

Rué²,

Kennedy³

et al. 2013

Croat. Chem. Acta

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Abstract. Known borane polyhedral cluster characteristics can be used for predicting new architectural constructs. We propose additional structures derived from B 18 H 22 : three positional isomers different from the well-known anti-B 18 H 22 and syn-B 18 H 22 boranes. We have also derived two new cyclic structures based on the condensation of borane pentagonal pyramids and bipyramids. The concatenation of polyhedral borane molecules is also considered from a mathematical point of view.

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The Preparation of a New Boron Hydride B₁₈H₂₂

Cited by 65 publications

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A borane laser

A borane laser

Substitution of the laser borane anti-B₁₈H₂₂ with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron hydrides

Borane Polyhedra as Building Blocks for Unknown but Potentially Isolatable New Molecules – Extensions based on Computations of the Known B18H22 Isomers

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The Preparation of a New Boron Hydride B18H22

Cited by 65 publications

References 0 publications

A borane laser

A borane laser

Substitution of the laser borane anti-B18H22 with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron hydrides

Borane Polyhedra as Building Blocks for Unknown but Potentially Isolatable New Molecules – Extensions based on Computations of the Known B18H22 Isomers

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The Preparation of a New Boron Hydride B₁₈H₂₂

Substitution of the laser borane anti-B₁₈H₂₂ with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron hydrides