Molecules

Research

Jump to: Review

14 pages, 3939 KiB

Open AccessArticle

New Boron Containing Acridines: Synthesis and Preliminary Biological Study

by Anna A. Druzina, Nadezhda V. Dudarova, Ivan V. Ananyev, Anastasia A. Antonets, Dmitry N. Kaluzhny, Alexey A. Nazarov, Igor B. Sivaev and Vladimir I. Bregadze

Molecules 2023, 28(18), 6636; https://doi.org/10.3390/molecules28186636 - 15 Sep 2023

Cited by 1 | Viewed by 1396

Abstract

The synthesis of the first conjugates of acridine with cobalt bis(dicarbollide) are reported. A novel 9-azido derivative of acridine was prepared through the reaction of 9-methoxyacridine with N₃CH₂CH₂NH₂, and its solid-state molecular structure was determined [...] Read more.

The synthesis of the first conjugates of acridine with cobalt bis(dicarbollide) are reported. A novel 9-azido derivative of acridine was prepared through the reaction of 9-methoxyacridine with N₃CH₂CH₂NH₂, and its solid-state molecular structure was determined via single-crystal X-ray diffraction. The azidoacridine was used in a copper (I)-catalyzed azide-alkyne cycloaddition reaction with cobalt bis(dicarbollide)-based terminal alkynes to give the target 1,2,3-triazoles. DNA interaction studies via absorbance spectroscopy showed the weak binding of the obtained conjugates with DNA. The antiproliferative activity (IC₅₀) of the boronated conjugates against a series of human cell lines was evaluated through an MTT assay. The results suggested that acridine derivatives of cobalt bis(dicarbollide) might serve as a novel scaffold for the future development of new agents for boron neutron capture therapy (BNCT). Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

16 pages, 2673 KiB

Open AccessArticle

The Synthesis, Characterization, and Fluxional Behavior of a Hydridorhodatetraborane

by Fatou Diaw-Ndiaye, Pablo J. Sanz Miguel, Ricardo Rodríguez and Ramón Macías

Molecules 2023, 28(18), 6462; https://doi.org/10.3390/molecules28186462 - 6 Sep 2023

Cited by 2 | Viewed by 1398

Abstract

The octahydridotriborate anion plays a crucial role in the field of polyhedral boron chemistry, facilitating the synthesis of higher boranes and the preparation of diverse transition metal complexes. Among the stable forms of this anion, CsB₃H₈ (or (n-C₄H [...] Read more.

The octahydridotriborate anion plays a crucial role in the field of polyhedral boron chemistry, facilitating the synthesis of higher boranes and the preparation of diverse transition metal complexes. Among the stable forms of this anion, CsB₃H₈ (or (n-C₄H₉)₄N)[B₃H₈] have been identified. These salts serve as valuable precursors for the synthesis of metallaboranes, wherein the triborate anion acts as a ligand coordinating to the metal center. In this study, we have successfully synthesized a novel rhodatetraborane dihydride, [Rh(η²-B₃H₈)(H)₂(PPh₃)₂] (1), which represents a Rh(III) complex featuring a bidentate chelate ligand fasormed by B₃H₈⁻. Extensive characterization of this rhodatetraborane complex has been performed using NMR spectroscopy in solution and X-ray diffraction analysis in the solid state. Notably, the complex exhibits intriguing fluxional behavior, which has been investigated using NMR techniques. Moreover, we have explored the reactivity of complex 1 towards pyridine (py) and dimethylphenylphosphine (PMe₂Ph). Our findings highlight the labile nature of this four-vertex rhodatetraborane as it undergoes disassembly upon attack from the corresponding Lewis base, resulting in the formation of borane adducts, LBH₃, where L = py, PMe₂Ph. Furthermore, in these reactions, we report the characterization of new cationic hydride complexes, such as [Rh(H)₂(PPh₃)₂ (py)]⁺ (2) and [Rh(H)₂(PMe₂Ph)₄]⁺. Notably, the latter complex has been characterized as the octahydridotriborate salt [Rh(H)₂(PMe₂Ph)₄][B₃H₈] (3), which extends the scope of rhodatetraborane derivatives. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

20 pages, 7866 KiB

Open AccessArticle

Synthesis, Reactivity and Coordination Chemistry of Group 9 PBP Boryl Pincer Complexes: [(PBP)M(PMe₃)_n] (M = Co, Rh, Ir; n = 1, 2)

by Philipp M. Rutz, Jörg Grunenberg and Christian Kleeberg

Molecules 2023, 28(17), 6191; https://doi.org/10.3390/molecules28176191 - 22 Aug 2023

Cited by 1 | Viewed by 1766

Abstract

The unsymmetrical diborane(4) derivative [(d(CH₂P(iPr)₂)abB)–Bpin] (1) proved to be a versatile PBP boryl pincer ligand precursor for Co(I) (2a, 4a), Rh(I) (2–3b) and Ir(I/III) (2–3c [...] Read more.

The unsymmetrical diborane(4) derivative [(d(CH₂P(iPr)₂)abB)–Bpin] (1) proved to be a versatile PBP boryl pincer ligand precursor for Co(I) (2a, 4a), Rh(I) (2–3b) and Ir(I/III) (2–3c, 5–6c) complexes, in particular of the types [(d(CH₂P(iPr)₂)abB)M(PMe₃)₂] (2a–c) and [(d(CH₂P(iPr)₂)abB)M–PMe₃] (2b–c). Whilst similar complexes have been obtained before, for the first time, the coordination chemistry of a homologous series of PBP pincer complexes, in particular the interconversion of the five- and four-coordinate complexes 2a–c/3a–c, was studied in detail. For Co, instead of the mono phosphine complex 2a, the dinitrogen complex [(d(CH₂P(iPr)₂)abB)Co(N₂)(PMe₃)] (4a) is formed spontaneously upon PMe₃ abstraction from 2a in the presence of N₂. All complexes were comprehensively characterised spectroscopically in solution via multinuclear (VT-)NMR spectroscopy and structurally in the solid state through single-crystal X-ray diffraction. The unique properties of the PBP ligand with respect to its coordination chemical properties are addressed. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

13 pages, 5383 KiB

Open AccessCommunication

1,8-Dihydroxy Naphthalene—A New Building Block for the Self-Assembly with Boronic Acids and 4,4′-Bipyridine to Stable Host–Guest Complexes with Aromatic Hydrocarbons

by Chamila P. Manankandayalage, Daniel K. Unruh, Ryan Perry and Clemens Krempner

Molecules 2023, 28(14), 5394; https://doi.org/10.3390/molecules28145394 - 14 Jul 2023

Viewed by 1336

Abstract

The new Lewis acid–base adducts of general formula X(nad)B←NC₅H₄-C₅H₄N→B(nad)X [nad = 1,8-O₂C₁₀H_6, X = C₆H₅ (2c), 3,4,5-F₃-C₆H₂ (2d)] [...] Read more.

The new Lewis acid–base adducts of general formula X(nad)B←NC₅H₄-C₅H₄N→B(nad)X [nad = 1,8-O₂C₁₀H_6, X = C₆H₅ (2c), 3,4,5-F₃-C₆H₂ (2d)] were synthesized in high yields via reactions of 1,8-dihydroxy naphthalene [nadH₂] and 4,4′-bipyridine with the aryl boronic acids C₆H₅B(OH)₂ and 3,4,5-F₃-C₆H₂B(OH)₂, respectively, and structurally characterized by multi-nuclear NMR spectroscopy and SCXRD. Self-assembled H-shaped Lewis acid–base adduct 2d proved to be effective in forming thermally stable host–guest complexes, 2d × solvent, with aromatic hydrocarbon solvents such as benzene, toluene, mesitylene, aniline, and m-, p-, and o-xylene. Crystallographic analysis of these solvent adducts revealed host–guest interactions to primarily occur via π···π contacts between the 4,4′-bipyridyl linker and the aromatic solvents, resulting in the formation of 1:1 and 1:2 host–guest complexes. Thermogravimetric analysis of the isolated complexes 2d × solvent revealed their high thermal stability with peak temperatures associated with the loss of solvent ranging from 122 to 147 °C. 2d, when self-assembled in an equimolar mixture of m-, p-, and o-xylene (1:1:1), preferentially binds to o-xylene. Collectively, these results demonstrate the ability of 1,8-dihydroxy naphthalene to serve as an effective building block in the selective self-assembly to supramolecular aggregates through dative covalent N→B bonds. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

16 pages, 2680 KiB

Open AccessArticle

Synthesis and Structural Characterization of Copper Complexes Containing “R-Substituted” Bis-7-Azaindolyl Borate Ligands

by Miriam Jackson, Simon D. Thomas, Graham J. Tizzard, Simon J. Coles and Gareth R. Owen

Molecules 2023, 28(12), 4825; https://doi.org/10.3390/molecules28124825 - 17 Jun 2023

Viewed by 1763

Abstract

The coordination chemistry of scorpionate ligands based on borates containing the 7-azaindole heterocycle is relatively unexplored. Thus, there is a requirement to further understand their coordination chemistry. This article outlines the synthesis and characterization of a family of complexes containing anionic flexible scorpionate [...] Read more.

The coordination chemistry of scorpionate ligands based on borates containing the 7-azaindole heterocycle is relatively unexplored. Thus, there is a requirement to further understand their coordination chemistry. This article outlines the synthesis and characterization of a family of complexes containing anionic flexible scorpionate ligands of the type [(R)(bis-7-azaindolyl)borohydride]⁻ ([^RBai]⁻), where R = Me, Ph or naphthyl. The three ligands were coordinated to a series of copper(I) complexes containing a phosphine co-ligand to form the complexes, [Cu(^MeBai)(PPh₃)] (1), [Cu(^PhBai)(PPh₃)] (2), [Cu(^NaphthBai)(PPh₃)] (3), [Cu(^MeBai)(PCy₃)] (4), [Cu(^PhBai)(PCy₃)] (5) and [Cu(^NaphthBai)(PCy₃)] (6). Additional copper(II) complexes, namely, [Cu(^MeBai)₂] (7) and [Cu(^PhBai)₂] (8), were obtained during attempts to obtain single crystals from complexes 4 and 2, respectively. Complexes 7 and 8 were also prepared independently from CuCl₂ and two equivalents of the corresponding Li[^RBai] salt alongside an additional complex, namely, [Cu(^NaphthBai)₂] (9). The copper(I) and copper(II) complexes were characterized using spectroscopic and analytical methods. Furthermore, a crystal structure was obtained for eight of the nine complexes. In all cases, the boron-based ligand was found to bind to the metal centers via a κ³-N,N,H coordination mode. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

23 pages, 3546 KiB

Open AccessArticle

Synthesis and In Vitro Biological Evaluation of p-Carborane-Based Di-tert-butylphenol Analogs

by Sebastian Braun, Sanja Jelača, Markus Laube, Sven George, Bettina Hofmann, Peter Lönnecke, Dieter Steinhilber, Jens Pietzsch, Sanja Mijatović, Danijela Maksimović-Ivanić and Evamarie Hey-Hawkins

Molecules 2023, 28(11), 4547; https://doi.org/10.3390/molecules28114547 - 4 Jun 2023

Cited by 3 | Viewed by 2346

Abstract

Targeting inflammatory mediators and related signaling pathways may offer a rational strategy for the treatment of cancer. The incorporation of metabolically stable, sterically demanding, and hydrophobic carboranes in dual cycloxygenase-2 (COX-2)/5-lipoxygenase (5-LO) inhibitors that are key enzymes in the biosynthesis of eicosanoids is [...] Read more.

Targeting inflammatory mediators and related signaling pathways may offer a rational strategy for the treatment of cancer. The incorporation of metabolically stable, sterically demanding, and hydrophobic carboranes in dual cycloxygenase-2 (COX-2)/5-lipoxygenase (5-LO) inhibitors that are key enzymes in the biosynthesis of eicosanoids is a promising approach. The di-tert-butylphenol derivatives R-830, S-2474, KME-4, and E-5110 represent potent dual COX-2/5-LO inhibitors. The incorporation of p-carborane and further substitution of the p-position resulted in four carborane-based di-tert-butylphenol analogs that showed no or weak COX inhibition but high 5-LO inhibitory activities in vitro. Cell viability studies on five human cancer cell lines revealed that the p-carborane analogs R-830-Cb, S-2474-Cb, KME-4-Cb, and E-5110-Cb exhibited lower anticancer activity compared to the related di-tert-butylphenols. Interestingly, R-830-Cb did not affect the viability of primary cells and suppressed HCT116 cell proliferation more potently than its carbon-based R-830 counterpart. Considering all the advantages of boron cluster incorporation for enhancement of drug biostability, selectivity, and availability of drugs, R-830-Cb can be tested in further mechanistic and in vivo studies. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

15 pages, 2843 KiB

Open AccessArticle

A Window into the Workings of anti-B₁₈H₂₂ Luminescence—Blue-Fluorescent Isomeric Pair 3,3′-Cl₂-B₁₈H₂₀ and 3,4′-Cl₂-B₁₈H₂₀ (and Others)

by Marcel Ehn, Dmytro Bavol, Jonathan Bould, Vojtěch Strnad, Miroslava Litecká, Kamil Lang, Kaplan Kirakci, William Clegg, Paul G. Waddell and Michael G. S. Londesborough

Molecules 2023, 28(11), 4505; https://doi.org/10.3390/molecules28114505 - 1 Jun 2023

Cited by 3 | Viewed by 2278

Abstract

The action of AlCl₃ on room-temperature tetrachloromethane solutions of anti-B₁₈H₂₂ (1) results in a mixture of fluorescent isomers, 3,3′-Cl₂-B₁₈H₂₀ (2) and 3,4′-Cl₂-B₁₈H₂₀ (3 [...] Read more.

The action of AlCl₃ on room-temperature tetrachloromethane solutions of anti-B₁₈H₂₂ (1) results in a mixture of fluorescent isomers, 3,3′-Cl₂-B₁₈H₂₀ (2) and 3,4′-Cl₂-B₁₈H₂₀ (3), together isolated in a 76% yield. Compounds 2 and 3 are capable of the stable emission of blue light under UV-excitation. In addition, small amounts of other dichlorinated isomers, 4,4′-Cl₂-B₁₈H₂₀ (4), 3,1′-Cl₂-B₁₈H₂₀ (5), and 7,3′-Cl₂-B₁₈H₂₀ (6) were isolated, along with blue-fluorescent monochlorinated derivatives, 3-Cl-B₁₈H₂₁ (7) and 4-Cl-B₁₈H₂₁ (8), and trichlorinated species 3,4,3′-Cl₃-B₁₈H₁₉ (9) and 3,4,4′-Cl₃-B₁₈H₁₉ (10). The molecular structures of these new chlorinated derivatives of octadecaborane are delineated, and the photophysics of some of these species are discussed in the context of the influence that chlorination bears on the luminescence of anti-B₁₈H₂₂. In particular, this study produces important information on the effect that the cluster position of these substitutions has on luminescence quantum yields and excited-state lifetimes. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

10 pages, 8811 KiB

Open AccessArticle

Two New Aluminoborates with 3D Porous-Layered Frameworks

by Chen Wang, Juan Chen, Chong-An Chen, Zhen-Wen Wang and Guo-Yu Yang

Molecules 2023, 28(11), 4387; https://doi.org/10.3390/molecules28114387 - 27 May 2023

Cited by 1 | Viewed by 1214

Abstract

Two new aluminoborates, NaKCs[AlB₇O₁₃(OH)]·H₂O (1) and K₄Na₅[AlB₇O₁₃(OH)]₃·5H₂O (2), have been hydro(solvo)thermally made with mixed alkali metal cationic templates. Both 1 and [...] Read more.

Two new aluminoborates, NaKCs[AlB₇O₁₃(OH)]·H₂O (1) and K₄Na₅[AlB₇O₁₃(OH)]₃·5H₂O (2), have been hydro(solvo)thermally made with mixed alkali metal cationic templates. Both 1 and 2 crystallize in the monoclinic space group P2₁/n and contain similar units of [B₇O₁₃(OH)]⁶⁻ cluster and AlO₄ tetrahedra. The [B₇O₁₃(OH)]⁶⁻ cluster is composed of three classical B₃O₃ rings by vertex sharing, of which two of them connect with AlO₄ tetrahedra to constitute monolayers, and one provides an O atom as a bridging unit to link two oppositely orientated monolayers by Al-O bonds to form 3D porous-layered frameworks with 8-MR channels. UV-Vis diffuse reflectance spectra indicate that both 1 and 2 exhibit short deep-UV cutoff edges below 190 nm, revealing that they have potential applications in deep-UV regions. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

11 pages, 2751 KiB

Open AccessFeature PaperArticle

The Nature of the (Oligo/Hetero)Arene Linker Connecting Two Triarylborane Cations Controls Fluorimetric and Circular Dichroism Sensing of Various ds-DNAs and ds-RNAs

by Lidija-Marija Tumir, Dijana Pavlović Saftić, Ivo Crnolatac, Željka Ban, Matea Maslać, Stefanie Griesbeck, Todd B. Marder and Ivo Piantanida

Molecules 2023, 28(11), 4348; https://doi.org/10.3390/molecules28114348 - 25 May 2023

Viewed by 1557

Abstract

A series of tetracationic bis-triarylborane dyes, differing in the aromatic linker connecting two dicationic triarylborane moieties, showed very high submicromolar affinities toward ds-DNA and ds-RNA. The linker strongly influenced the emissive properties of triarylborane cations and controlled the fluorimetric response of dyes. The [...] Read more.

A series of tetracationic bis-triarylborane dyes, differing in the aromatic linker connecting two dicationic triarylborane moieties, showed very high submicromolar affinities toward ds-DNA and ds-RNA. The linker strongly influenced the emissive properties of triarylborane cations and controlled the fluorimetric response of dyes. The fluorene-analog shows the most selective fluorescence response between AT-DNA, GC-DNA, and AU-RNA, the pyrene-analog’s emission is non-selectively enhanced by all DNA/RNA, and the dithienyl-diketopyrrolopyrrole analog’s emission is strongly quenched upon DNA/RNA binding. The emission properties of the biphenyl-analog were not applicable, but the compound showed specific induced circular dichroism (ICD) signals only for AT-sequence-containing ds-DNAs, whereas the pyrene-analog ICD signals were specific for AT-DNA with respect to GC-DNA, and also recognized AU-RNA by giving a different ICD pattern from that observed upon interaction with AT-DNA. The fluorene- and dithienyl-diketopyrrolopyrrole analogs were ICD-signal silent. Thus, fine-tuning of the aromatic linker properties connecting two triarylborane dications can be used for the dual sensing (fluorimetric and CD) of various ds-DNA/RNA secondary structures, depending on the steric properties of the DNA/RNA grooves. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

17 pages, 4165 KiB

Open AccessArticle

Metallacarborane Synthons for Molecular Construction—Oligofunctionalization of Cobalt Bis(1,2-dicarbollide) on Boron and Carbon Atoms with Extendable Ligands

by Krzysztof Śmiałkowski, Carla Sardo and Zbigniew J. Leśnikowski

Molecules 2023, 28(10), 4118; https://doi.org/10.3390/molecules28104118 - 16 May 2023

Cited by 1 | Viewed by 1766

Abstract

The exploitation of metallacarboranes’ potential in various fields of research and practical applications requires the availability of convenient and versatile methods for their functionalization with various functional moieties and/or linkers of different types and lengths. Herein, we report a study on cobalt bis(1,2-dicarbollide) [...] Read more.

The exploitation of metallacarboranes’ potential in various fields of research and practical applications requires the availability of convenient and versatile methods for their functionalization with various functional moieties and/or linkers of different types and lengths. Herein, we report a study on cobalt bis(1,2-dicarbollide) functionalization at 8,8′-boron atoms with different hetero-bifunctional moieties possessing a protected hydroxyl function allowing further modification after deprotection. Moreover, an approach to the synthesis of three and four functionalized metallacarboranes, at boron and carbon atoms simultaneously via additional functionalization at carbon to obtain derivatives carrying three or four rationally oriented and distinct reactive surfaces, is described. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

11 pages, 2584 KiB

Open AccessArticle

Synthesis and Structural Characterization of p-Carboranylamidine Derivatives

by Nicole Harmgarth, Phil Liebing, Volker Lorenz, Felix Engelhardt, Liane Hilfert, Sabine Busse, Rüdiger Goldhahn and Frank T. Edelmann

Molecules 2023, 28(9), 3837; https://doi.org/10.3390/molecules28093837 - 30 Apr 2023

Cited by 1 | Viewed by 1750

Abstract

In this contribution, the first amidinate and amidine derivatives of p-carborane are described. Double lithiation of p-carborane (1) with n-butyllithium followed by treatment with 1,3-diorganocarbodiimides, R–N=C=N–R (R = ⁱPr, Cy (= cyclohexyl)), in DME or THF afforded [...] Read more.

In this contribution, the first amidinate and amidine derivatives of p-carborane are described. Double lithiation of p-carborane (1) with n-butyllithium followed by treatment with 1,3-diorganocarbodiimides, R–N=C=N–R (R = ⁱPr, Cy (= cyclohexyl)), in DME or THF afforded the new p-carboranylamidinate salts p-C₂H₁₀B₁₀[C(NⁱPr)₂Li(DME)]₂ (2) and p-C₂H₁₀B₁₀[C(NCy)₂Li(THF)₂]₂ (3). Subsequent treatment of 2 and 3 with 2 equiv. of chlorotrimethylsilane (Me₃SiCl) provided the silylated neutral bis(amidine) derivatives p-C₂H₁₀B₁₀[C{ⁱPrN(SiMe₃)}(=NⁱPr)]₂ (4) and p-C₂H₁₀B₁₀[C{CyN(SiMe₃)}(=NCy)]₂ (5). The new compounds 3 and 4 have been structurally characterized by single-crystal X-ray diffraction. The lithium carboranylamidinate 3 comprises a rare trigonal planar coordination geometry around the lithium ions. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

13 pages, 5709 KiB

Open AccessArticle

DFT Surface Infers Ten-Vertex Cationic Carboranes from the Corresponding Neutral closo Ten-Vertex Family: The Computed Background Confirming Their Experimental Availability

by Michael L. McKee, Jan Vrána, Josef Holub, Jindřich Fanfrlík and Drahomír Hnyk

Molecules 2023, 28(8), 3645; https://doi.org/10.3390/molecules28083645 - 21 Apr 2023

Viewed by 1396

Abstract

Modern computational protocols based on the density functional theory (DFT) infer that polyhedral closo ten-vertex carboranes are key starting stationary states in obtaining ten-vertex cationic carboranes. The rearrangement of the bicapped square polyhedra into decaborane-like shapes with open hexagons in boat conformations is [...] Read more.

Modern computational protocols based on the density functional theory (DFT) infer that polyhedral closo ten-vertex carboranes are key starting stationary states in obtaining ten-vertex cationic carboranes. The rearrangement of the bicapped square polyhedra into decaborane-like shapes with open hexagons in boat conformations is caused by attacks of N-heterocyclic carbenes (NHCs) on the closo motifs. Single-point computations on the stationary points found during computational examinations of the reaction pathways have clearly shown that taking the “experimental” NHCs into account requires the use of dispersion correction. Further examination has revealed that for the purposes of the description of reaction pathways in their entirety, i.e., together with all transition states and intermediates, a simplified model of NHCs is sufficient. Many of such transition states resemble in their shapes those that dictate Z-rearrangement among various isomers of closo ten-vertex carboranes. Computational results are in very good agreement with the experimental findings obtained earlier. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

11 pages, 2212 KiB

Open AccessArticle

Synthesis of Novel Carborane-Containing Derivatives of RGD Peptide

by Alexander V. Vakhrushev, Dmitry A. Gruzdev, Alexander M. Demin, Galina L. Levit and Victor P. Krasnov

Molecules 2023, 28(8), 3467; https://doi.org/10.3390/molecules28083467 - 14 Apr 2023

Cited by 1 | Viewed by 1864

Abstract

Short peptides containing the Arg-Gly-Asp (RGD) fragment can selectively bind to integrins on the surface of tumor cells and are attractive transport molecules for the targeted delivery of therapeutic and diagnostic agents to tumors (for example, glioblastoma). We have demonstrated the possibility of [...] Read more.

Short peptides containing the Arg-Gly-Asp (RGD) fragment can selectively bind to integrins on the surface of tumor cells and are attractive transport molecules for the targeted delivery of therapeutic and diagnostic agents to tumors (for example, glioblastoma). We have demonstrated the possibility of obtaining the N- and C-protected RGD peptide containing 3-amino-closo-carborane and a glutaric acid residue as a linker fragment. The resulting carboranyl derivatives of the protected RGD peptide are of interest as starting compounds in the synthesis of unprotected or selectively protected peptides, as well as building blocks for preparation of boron-containing derivatives of the RGD peptide of a more complex structure. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

16 pages, 2810 KiB

Open AccessArticle

Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides

by P. Veeraraghavan Ramachandran and Henry J. Hamann

Molecules 2023, 28(8), 3433; https://doi.org/10.3390/molecules28083433 - 13 Apr 2023

Viewed by 2001

Abstract

Dehydrogenative borylation of terminal alkynes has recently emerged as an atom-economical one-step alternative to traditional alkyne borylation methodologies. Using lithium aminoborohydrides, formed in situ from the corresponding amine-boranes and n-butyllithium, a variety of aromatic and aliphatic terminal alkyne substrates were successfully borylated [...] Read more.

Dehydrogenative borylation of terminal alkynes has recently emerged as an atom-economical one-step alternative to traditional alkyne borylation methodologies. Using lithium aminoborohydrides, formed in situ from the corresponding amine-boranes and n-butyllithium, a variety of aromatic and aliphatic terminal alkyne substrates were successfully borylated in high yield. The potential to form mono-, di-, and tri-B-alkynylated products has been shown, though the mono-product is primarily generated using the presented condition. The reaction has been demonstrated at large (up to 50 mmol) scale, and the products are stable to column chromatography as well as acidic and basic aqueous conditions. Alternately, the dehydroborylation can be achieved by treating alkynyllithiums with amine-boranes. In that respect, aldehydes can act as starting materials by conversion to the 1,1-dibromoolefin and in situ rearrangement to the lithium acetylide. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

15 pages, 2790 KiB

Open AccessArticle

Structural (XRD) Characterization and an Analysis of H-Bonding Motifs in Some Tetrahydroxidohexaoxidopentaborate(1-) Salts of N-Substituted Guanidinium Cations

by Michael A. Beckett, Simon J. Coles, Peter N. Horton and Thomas A. Rixon

Molecules 2023, 28(7), 3273; https://doi.org/10.3390/molecules28073273 - 6 Apr 2023

Cited by 2 | Viewed by 1764

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] ( [...] Read more.

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. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

9 pages, 1218 KiB

Open AccessCommunication

Facile Attachment of Halides and Pseudohalides to Dodecaborate(2-) via Pd-catalyzed Cross-Coupling

by Mahmoud K. Al-Joumhawy, Jui-Chi Chang, Fariba Sabzi and Detlef Gabel

Molecules 2023, 28(7), 3245; https://doi.org/10.3390/molecules28073245 - 5 Apr 2023

Cited by 5 | Viewed by 1983

Abstract

Cross-coupling reactions with [B₁₂H₁₁I]²⁻ as one partner have been used successfully for Kumada and Buchwald Hartwig couplings with Pd catalysis. Here, we found that the iodide could be substituted easily, and unexpectedly, with other halides such as Br [...] Read more.

Cross-coupling reactions with [B₁₂H₁₁I]²⁻ as one partner have been used successfully for Kumada and Buchwald Hartwig couplings with Pd catalysis. Here, we found that the iodide could be substituted easily, and unexpectedly, with other halides such as Br and Cl, and with pseudohalides such as cyanide, azide, and isocyanate. We found that for Cl, Br, N₃, and NCO, tetrabutylammonium salts—or sodium salts—were successful halide sources, whereas for cyanide, CuCN was the only halide source that allowed a successful exchange. The azide could be reacted further in a click reaction with triazoles. While no substitution with fluoride occurred, tetrabutylammonium fluoride in the presence of water led to [B₁₂H₁₁OH]²⁻. Yields were high to very high, and reaction times were short when using a microwave oven as a heating source. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Scheme 1

17 pages, 3666 KiB

Open AccessArticle

Polyhedral Dicobaltadithiaboranes and Dicobaltdiselenaboranes as Examples of Bimetallic Nido Structures without Bridging Hydrogens

by Amr A. A. Attia, Alexandru Lupan and Robert Bruce King

Molecules 2023, 28(7), 2988; https://doi.org/10.3390/molecules28072988 - 27 Mar 2023

Viewed by 1695

Abstract

The geometries and energetics of the n-vertex polyhedral dicobaltadithiaboranes and dicobaltadiselenaboranes Cp₂Co₂E₂B_n₋₄H_n₋₄ (E = S, Se; n = 8 to 12) have been investigated via the density functional theory. Most of [...] Read more.

The geometries and energetics of the n-vertex polyhedral dicobaltadithiaboranes and dicobaltadiselenaboranes Cp₂Co₂E₂B_n₋₄H_n₋₄ (E = S, Se; n = 8 to 12) have been investigated via the density functional theory. Most of the lowest-energy structures in these systems are generated from the (n + 1)-vertex most spherical closo deltahedra by removal of a single vertex, leading to a tetragonal, pentagonal, or hexagonal face depending on the degree of the vertex removed. In all of these low-energy structures, the chalcogen atoms are located at the vertices of the non-triangular face. Alternatively, the central polyhedron in most of the 12-vertex structures can be derived from a Co₂E₂B₈ icosahedron with adjacent chalcogen (E) vertices by breaking the E–E edge and 1 or more E–B edges to create a hexagonal face. Examples of the arachno polyhedra with two tetragonal and/or pentagonal faces derived from the removal of two vertices from isocloso deltahedra were found among the set of lowest-energy Cp₂Co₂E₂B_n₋₄H_n₋₄ (E = S, Se; n = 8 and 12) structures. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

12 pages, 3283 KiB

Open AccessArticle

Thermal Polymorphism in CsCB₁₁H₁₂

by Radovan Černý, Matteo Brighi, Hui Wu, Wei Zhou, Mirjana Dimitrievska, Fabrizio Murgia, Valerio Gulino, Petra E. de Jongh, Benjamin A. Trump and Terrence J. Udovic

Molecules 2023, 28(5), 2296; https://doi.org/10.3390/molecules28052296 - 1 Mar 2023

Cited by 1 | Viewed by 2558

Abstract

Thermal polymorphism in the alkali-metal salts incorporating the icosohedral monocarba-hydridoborate anion, CB₁₁H₁₂⁻, results in intriguing dynamical properties leading to superionic conductivity for the lightest alkali-metal analogues, LiCB₁₁H₁₂ and NaCB₁₁H₁₂. As such, [...] Read more.

Thermal polymorphism in the alkali-metal salts incorporating the icosohedral monocarba-hydridoborate anion, CB₁₁H₁₂⁻, results in intriguing dynamical properties leading to superionic conductivity for the lightest alkali-metal analogues, LiCB₁₁H₁₂ and NaCB₁₁H₁₂. As such, these two have been the focus of most recent CB₁₁H₁₂⁻ related studies, with less attention paid to the heavier alkali-metal salts, such as CsCB₁₁H₁₂. Nonetheless, it is of fundamental importance to compare the nature of the structural arrangements and interactions across the entire alkali-metal series. Thermal polymorphism in CsCB₁₁H₁₂ was investigated using a combination of techniques: X-ray powder diffraction; differential scanning calorimetry; Raman, infrared, and neutron spectroscopies; and ab initio calculations. The unexpected temperature-dependent structural behavior of anhydrous CsCB₁₁H₁₂ can be potentially justified assuming the existence of two polymorphs with similar free energies at room temperature: (i) a previously reported, ordered R3 polymorph stabilized upon drying and transforming first to R3c symmetry near 313 K and then to a similarly packed but disordered I43d polymorph near 353 K and (ii) a disordered Fm3 polymorph that initially appears from the disordered I43d polymorph near 513 K along with another disordered high-temperature P6₃mc polymorph. Quasielastic neutron scattering results indicate that the CB₁₁H₁₂⁻ anions in the disordered phase at 560 K are undergoing isotropic rotational diffusion, with a jump correlation frequency [1.19(9) × 10¹¹ s⁻¹] in line with those for the lighter-metal analogues. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

16 pages, 2632 KiB

Open AccessArticle

Synthesis: Molecular Structure, Thermal-Calorimetric and Computational Analyses, of Three New Amine Borane Adducts

by Kevin Turani-I-Belloto, Rodica Chiriac, François Toche, Eddy Petit, Pascal G. Yot, Johan G. Alauzun and Umit B. Demirci

Molecules 2023, 28(3), 1469; https://doi.org/10.3390/molecules28031469 - 3 Feb 2023

Cited by 1 | Viewed by 2090

Abstract

Cyclopropylamine borane C₃H₅NH₂BH₃ (C3AB), 2-ethyl-1-hexylamine borane CH₃(CH₂)₃CH(C₂H₅)CH₂NH₂BH₃ (C2C6AB) and didodecylamine borane (C₁₂H₂₅)₂NHBH₃ ((C12)2AB) are [...] Read more.

Cyclopropylamine borane C₃H₅NH₂BH₃ (C3AB), 2-ethyl-1-hexylamine borane CH₃(CH₂)₃CH(C₂H₅)CH₂NH₂BH₃ (C2C6AB) and didodecylamine borane (C₁₂H₂₅)₂NHBH₃ ((C12)2AB) are three new amine borane adducts (ABAs). They are synthesized by reaction of the corresponding amines with a borane complex, the reaction being exothermic as shown by Calvet calorimetry. The successful synthesis of each has been demonstrated by FTIR, Raman and NMR. For instance, the ¹¹B NMR spectra show the presence of signals typical of the NBH₃ environment, thereby implying the formation of B–N bonds. The occurrence of dihydrogen bonds (DHBs) for each of the ABAs has been highlighted by DSC and FTIR, and supported by DFT calculations (via the Mulliken charges for example). When heated, the three ABAs behave differently: C3AB and C2C6AB decompose from 68 to 100 °C whereas (C12)2AB is relatively stable up to 173 °C. That means that these ABAs are not appropriate as hydrogen carriers, but the ‘most’ stable (C12)2AB could open perspectives for the synthesis of advanced materials. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

15 pages, 2716 KiB

Open AccessArticle

Incorporation of a Boron–Nitrogen Covalent Bond Improves the Charge-Transport and Charge-Transfer Characteristics of Organoboron Small-Molecule Acceptors for Organic Solar Cells

by Jie Yang, Wei-Lu Ding, Quan-Song Li and Ze-Sheng Li

Molecules 2023, 28(2), 811; https://doi.org/10.3390/molecules28020811 - 13 Jan 2023

Cited by 10 | Viewed by 3017

Abstract

An organoboron small-molecular acceptor (OSMA) M_B←N containing a boron–nitrogen coordination bond (B←N) exhibits good light absorption in organic solar cells (OSCs). In this work, based on M_B←N, OSMA M_B-N, with the incorporation of a boron–nitrogen covalent bond (B-N), [...] Read more.

An organoboron small-molecular acceptor (OSMA) M_B←N containing a boron–nitrogen coordination bond (B←N) exhibits good light absorption in organic solar cells (OSCs). In this work, based on M_B←N, OSMA M_B-N, with the incorporation of a boron–nitrogen covalent bond (B-N), was designed. We have systematically investigated the charge-transport properties and interfacial charge-transfer characteristics of M_B-N, along with M_B←N, using the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT). Theoretical calculations show that M_B-N can simultaneously boost the open-circuit voltage (from 0.78 V to 0.85 V) and the short-circuit current due to its high-lying lowest unoccupied molecular orbital and the reduced energy gap. Moreover, its large dipole shortens stacking and greatly enhances electron mobility by up to 5.91 × 10⁻³ cm²·V⁻¹·s⁻¹. Notably, the excellent interfacial properties of PTB7-Th/M_B-N, owing to more charge transfer states generated through the direct excitation process and the intermolecular electric field mechanism, are expected to improve OSCs performance. Together with the excellent properties of M_B-N, we demonstrate a new OSMA and develop a new organoboron building block with B-N units. The computations also shed light on the structure–property relationships and provide in-depth theoretical guidance for the application of organoboron photovoltaic materials. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

11 pages, 1792 KiB

Open AccessCommunication

Room Temperature Reduction of Titanium Tetrachloride-Activated Nitriles to Primary Amines with Ammonia-Borane

by P. Veeraraghavan Ramachandran and Abdulkhaliq A. Alawaed

Molecules 2023, 28(1), 60; https://doi.org/10.3390/molecules28010060 - 21 Dec 2022

Cited by 4 | Viewed by 3918

Abstract

The reduction of a variety of aromatic and aliphatic nitriles, activated by a molar equivalent of titanium tetrachloride, has been achieved at room temperature using ammonia borane as a safe reductant. The corresponding methanamines were isolated in good to excellent yields following a [...] Read more.

The reduction of a variety of aromatic and aliphatic nitriles, activated by a molar equivalent of titanium tetrachloride, has been achieved at room temperature using ammonia borane as a safe reductant. The corresponding methanamines were isolated in good to excellent yields following a simple acid-base workup. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

Review

Jump to: Research

67 pages, 34211 KiB

Open AccessReview

Chemistry of Carbon-Substituted Derivatives of Cobalt Bis(dicarbollide)(1⁻) Ion and Recent Progress in Boron Substitution

by Lucia Pazderová, Ece Zeynep Tüzün, Dmytro Bavol, Miroslava Litecká, Lukáš Fojt and Bohumír Grűner

Molecules 2023, 28(19), 6971; https://doi.org/10.3390/molecules28196971 - 7 Oct 2023

Cited by 11 | Viewed by 2007

Abstract

The cobalt bis(dicarbollide)(1⁻) anion (1⁻), [(1,2-C₂B₉H₁₁)₂-3,3′-Co(III)](1⁻), plays an increasingly important role in material science and medicine due to its high chemical stability, 3D shape, aromaticity, diamagnetic character, ability [...] Read more.

The cobalt bis(dicarbollide)(1⁻) anion (1⁻), [(1,2-C₂B₉H₁₁)₂-3,3′-Co(III)](1⁻), plays an increasingly important role in material science and medicine due to its high chemical stability, 3D shape, aromaticity, diamagnetic character, ability to penetrate cells, and low cytotoxicity. A key factor enabling the incorporation of this ion into larger organic molecules, biomolecules, and materials, as well as its capacity for “tuning” interactions with therapeutic targets, is the availability of synthetic routes that enable easy modifications with a wide selection of functional groups. Regarding the modification of the dicarbollide cage, syntheses leading to substitutions on boron atoms are better established. These methods primarily involve ring cleavage of the ether rings in species containing an oxonium oxygen atom connected to the B(8) site. These pathways are accessible with a broad range of nucleophiles. In contrast, the chemistry on carbon vertices has remained less elaborated over the previous decades due to a lack of reliable methods that permit direct and straightforward cage modifications. In this review, we present a survey of methods based on metalation reactions on the acidic C-H vertices, followed by reactions with electrophiles, which have gained importance in only the last decade. These methods now represent the primary trends in the modifications of cage carbon atoms. We discuss the scope of currently available approaches, along with the stereochemistry of reactions, chirality of some products, available types of functional groups, and their applications in designing unconventional drugs. This content is complemented with a report of the progress in physicochemical and biological studies on the parent cobalt bis(dicarbollide) ion and also includes an overview of recent syntheses and emerging applications of boron-substituted compounds. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

54 pages, 28158 KiB

Open AccessReview

Decaborane: From Alfred Stock and Rocket Fuel Projects to Nowadays

by Igor B. Sivaev

Molecules 2023, 28(17), 6287; https://doi.org/10.3390/molecules28176287 - 28 Aug 2023

Cited by 3 | Viewed by 2614

Abstract

The review covers more than a century of decaborane chemistry from the first synthesis by Alfred Stock to the present day. The main attention is paid to the reactions of the substitution of hydrogen atoms by various atoms and groups with the formation [...] Read more.

The review covers more than a century of decaborane chemistry from the first synthesis by Alfred Stock to the present day. The main attention is paid to the reactions of the substitution of hydrogen atoms by various atoms and groups with the formation of exo-polyhedral boron–halogen, boron–oxygen, boron–sulfur, boron–nitrogen, boron–phosphorus, and boron–carbon bonds. Particular attention is paid to the chemistry of conjucto-borane anti-[B₁₈H₂₂], whose structure is formed by two decaborane moieties with a common edge, the chemistry of which has been intensively developed in the last decade. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Graphical abstract

18 pages, 8081 KiB

Open AccessReview

Recent Progress in Crystalline Borates with Edge-Sharing BO₄ Tetrahedra

by Jing-Jing Li, Wei-Feng Chen, You-Zhao Lan and Jian-Wen Cheng

Molecules 2023, 28(13), 5068; https://doi.org/10.3390/molecules28135068 - 28 Jun 2023

Cited by 7 | Viewed by 1586

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

24 pages, 11487 KiB

Open AccessReview

Towards the Application of Purely Inorganic Icosahedral Boron Clusters in Emerging Nanomedicine

by Francesc Teixidor, Rosario Núñez and Clara Viñas

Molecules 2023, 28(11), 4449; https://doi.org/10.3390/molecules28114449 - 30 May 2023

Cited by 9 | Viewed by 2497

Abstract

Traditionally, drugs were obtained by extraction from medicinal plants, but more recently also by organic synthesis. Today, medicinal chemistry continues to focus on organic compounds and the majority of commercially available drugs are organic molecules, which can incorporate nitrogen, oxygen, and halogens, as [...] Read more.

Traditionally, drugs were obtained by extraction from medicinal plants, but more recently also by organic synthesis. Today, medicinal chemistry continues to focus on organic compounds and the majority of commercially available drugs are organic molecules, which can incorporate nitrogen, oxygen, and halogens, as well as carbon and hydrogen. Aromatic organic compounds that play important roles in biochemistry find numerous applications ranging from drug delivery to nanotechnology or biomarkers. We achieved a major accomplishment by demonstrating experimentally/theoretically that boranes, carboranes, as well as metallabis(dicarbollides), exhibit global 3D aromaticity. Based on the stability–aromaticity relationship, as well as on the progress made in the synthesis of derivatized clusters, we have opened up new applications of boron icosahedral clusters as key components in the field of novel healthcare materials. In this brief review, we present the results obtained at the Laboratory of Inorganic Materials and Catalysis (LMI) of the Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) with icosahedral boron clusters. These 3D geometric shape clusters, the semi-metallic nature of boron and the presence of exo-cluster hydrogen atoms that can interact with biomolecules through non-covalent hydrogen and dihydrogen bonds, play a key role in endowing these compounds with unique properties in largely unexplored (bio)materials. Full article

(This article belongs to the Special Issue New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday)

► Show Figures

Figure 1

Journal Menu

Journal Browser

New Developments in Boron Chemistry: From Oxidoborates to Hydrido(hetero)borane Derivatives – in Celebration of Professor John D. Kennedy’s 80th Birthday

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (25 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI