Sample records for carboranes

  1. Unprecedented formation of polycyclic diazadiborepine derivatives through cage deboronation of m-carborane. (United States)

    Harmgarth, Nicole; Hrib, Cristian G; Lorenz, Volker; Hilfert, Liane; Edelmann, Frank T


    An unprecedented deboronation reaction of icosahedral carboranes is described, in which a BH group of m-carborane is detached from the cage and incorporated into an unusual nido-carborane-anellated diazadiborepine ring system.

  2. Poly[di(2-thiophenyl)carborane]s: conducting polymers with high electrochemical and thermal resistance.



    International audience; The synthesis, X-ray structure and electropolymerization of three new carbon-carbon linked di(2-thiophenyl)carboranes (, and ) are reported; the resulting polymers bearing icosahedral ortho-, meta- or para-carborane clusters show high thermal and electrochemical stabilities in comparison with unsubstituted polythiophene; the ortho-carborane-containing polymer has the highest conductivity of the new materials.

  3. Poly[di(2-thiophenyl)carborane]s: conducting polymers with high electrochemical and thermal resistance. (United States)

    Hao, Erhong; Fabre, Bruno; Fronczek, Frank R; Vicente, M Graça H


    The synthesis, X-ray structure and electropolymerization of three new carbon-carbon linked di(2-thiophenyl)carboranes (, and ) are reported; the resulting polymers bearing icosahedral ortho-, meta- or para-carborane clusters show high thermal and electrochemical stabilities in comparison with unsubstituted polythiophene; the ortho-carborane-containing polymer has the highest conductivity of the new materials.

  4. N,O-Type Carborane-Based Materials

    Directory of Open Access Journals (Sweden)

    José Giner Planas


    Full Text Available This review summarizes the synthesis and coordination chemistry of a series of carboranyl ligands containing N,O donors. Such carborane-based ligands are scarcely reported in the literature when compared to other heteroatom-containing donors. The synthetic routes for metal complexes of these N,O-type carborane ligands are summarized and the properties of such complexes are described in detail. Particular attention is paid to the effect that the incorporation of carboranes has into the coordination chemistry of the otherwise carbon-based ligands and the properties of such materials. The reported complexes show a variety of properties such as those used in magnetic, chiroptical, nonlinear optical, catalytic and biomedical applications.

  5. Polymers containing borane or carborane cage compounds and related applications (United States)

    Bowen, III, Daniel E; Eastwood, Eric A


    Polymers comprising residues of cage compound monomers having at least one polyalkoxy silyl substituent are provided. The cage compound monomers are selected from borane cage compound monomers comprising at least 7 cage atoms and/or carborane cage compound monomers comprising 7 to 11 cage compound monomers. Such polymers can further comprise one or more reactive matrices and/or co-monomers covalently bound with the cage compound monomer residues. Articles of manufacture comprising such polymers are also disclosed.

  6. Carborane-containing urea-based inhibitors of glutamate carboxypeptidase II: Synthesis and structural characterization. (United States)

    Youn, Sihyun; Kim, Kyung Im; Ptacek, Jakub; Ok, Kiwon; Novakova, Zora; Kim, YunHye; Koo, JaeHyung; Barinka, Cyril; Byun, Youngjoo


    Glutamate carboxypeptidase II (GCPII) is a zinc metalloprotease on the surface of astrocytes which cleaves N-acetylaspartylglutamate to release N-acetylaspartate and glutamate. GCPII inhibitors can decrease glutamate concentration and play a protective role against apoptosis or degradation of brain neurons. Herein, we report the synthesis and structural analysis of novel carborane-based GCPII inhibitors. We determined the X-ray crystal structure of GCPII in complex with a carborane-containing inhibitor at 1.79Å resolution. The X-ray analysis revealed that the bulky closo-carborane cluster is located in the spacious entrance funnel region of GCPII, indicating that the carborane cluster can be further structurally modified to identify promising lead structures of novel GCPII inhibitors.

  7. Rational design of gold nanoparticles functionalized with carboranes for application in Boron Neutron Capture Therapy. (United States)

    Ciani, Laura; Bortolussi, Silva; Postuma, Ian; Cansolino, Laura; Ferrari, Cinzia; Panza, Luigi; Altieri, Saverio; Ristori, Sandra


    In this paper we propose a bottom-up approach to obtain new boron carriers built with ortho-carborane functionalized gold nanoparticles (GNPs) for applications in Boron Neutron Capture Therapy. The interaction between carboranes and the gold surface was assured by one or two SH-groups directly linked to the boron atoms of the B10C2 cage. This allowed obtaining stable, nontoxic systems, though optimal biological performance was hampered by low solubility in aqueous media. To improve cell uptake, the hydrophilic character of carborane functionalized GNPs was enhanced by further coverage with an appropriately tailored diblock copolymer (PEO-b-PCL). This polymer also contained pendant carboranes to provide anchoring to the pre-functionalized GNPs. In vitro tests, carried out on osteosarcoma cells, showed that the final vectors possessed excellent biocompatibility joint to the capacity of concentrating boron atoms in the target, which is encouraging evidenced to pursue applications in vivo.

  8. Palladium-catalyzed regioselective intramolecular coupling of o-carborane with aromatics via direct cage B-H activation. (United States)

    Quan, Yangjian; Xie, Zuowei


    Palladium-catalyzed intramolecular coupling of o-carborane with aromatics via direct cage B-H bond activation has been achieved, leading to the synthesis of a series of o-carborane-functionalized aromatics in high yields with excellent regioselectivity. In addition, the site selectivity can also be tuned by the substituents on cage carbon atom.

  9. Synthesis and structure-activity relationship of p-carborane-based non-secosteroidal vitamin D analogs. (United States)

    Fujii, Shinya; Kano, Atsushi; Songkram, Chalermkiat; Masuno, Hiroyuki; Taoda, Yoshiyuki; Kawachi, Emiko; Hirano, Tomoya; Tanatani, Aya; Kagechika, Hiroyuki


    1α,25-Dihydroxyvitamin D3 [1α,25(OH)₂D₃: 1] is a specific modulator of nuclear vitamin D receptor (VDR), and novel vitamin D analogs are therapeutic candidates for multiple clinical applications. We recently developed non-secosteroidal VDR agonists bearing a p-carborane cage (a carbon-containing boron cluster) as a hydrophobic core structure. These carborane derivatives are structurally quite different from classical secosteroidal vitamin D analogs. Here, we report systematic synthesis and activity evaluation of carborane-based non-secosteroidal vitamin D analogs. The structure-activity relationships of carborane derivatives are different from those of secosteroidal vitamin D derivatives, and in particular, the length and the substituent position of the dihydroxylated side chain are rather flexible in carborane derivatives. The structure-activity relationships presented here should be helpful in development of non-secosteroidal vitamin D analogs for clinical applications.

  10. Carborane derivative development for boron neutron capture therapy. Final report

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    Barnum, Beverly A.; Yan Hao; Moore, Roger; Hawthorne, M. Frederick; Baum, Kurt


    Boron Neutron Capture Therapy [BNCT] is a binary method of cancer therapy based on the capture of neutrons by a boron-10 atom [{sup 10}B]. Cytotoxic {sup 7}Li nuclei and {alpha}-particles are emitted, with a range in tissue of 9 and 5 {micro}m, respectively, about one cell diameter. The major obstacle to clinically viable BNCT is the selective localization of 5-30 ppm {sup 10}B in tumor cells required for effective therapy. A promising approach to BNCT is based on hydrophilic boron-rich oligomeric phosphate diesters, or ''trailers'' that have been shown to concentrate selectively in tumor tissue. Examples of these compounds were prepared previously at high cost using an automated DNA synthesizer. Direct synthesis methods are needed for the production of gram-scale quantities for further biological evaluation. The work accomplished as a result of the collaboration between Fluorochem, Inc. and UCLA demonstrates that short oligomers containing at least five carborane units with four phosphodiester linkages can be prepared in substantial quantities. This work was accomplished by the application of standard phosphoramidite coupling chemistry.

  11. Iridium-catalysed regioselective borylation of carboranes via direct B–H activation (United States)

    Cheng, Ruofei; Qiu, Zaozao; Xie, Zuowei


    Carboranes are carbon–boron molecular clusters, which can be viewed as three-dimensional analogues to benzene. They are finding many applications in medicine, materials and organometallic chemistry. On the other hand, their exceptional thermal and chemical stabilities, as well as 3D structures, make them very difficult to be functionalized, in particular the regioselective functionalization of BH vertex among ten similar B–H bonds. Here we report a very efficient iridium-catalysed borylation of cage B(3,6)–H bonds of o-carboranes with excellent yields and regioselectivity using bis(pinacolato)diboron (B2pin2) as a reagent. Selective cage B(4)–H borylation has also been achieved by introducing a bulky TBDMS (tert-butyldimethylsilyl) group to one cage carbon vertex. The resultant 3,6-(Bpin)2-o-carboranes are useful synthons for the synthesis of a wide variety of B(3,6)-difunctionalized o-carboranes bearing cage B–X (X=O, N, C, I and Br) bonds. PMID:28300061

  12. Carborane acids. New "strong yet gentle" acids for organic and inorganic chemistry. (United States)

    Reed, Christopher A


    Icosahedral carborane anions such as CHB11Cl11- are amongst the least coordinating, most chemically inert anions known. They are also amongst the least basic, so their conjugate acids, H(carborane), are superacids (i.e. stronger than 100% H2SO4). Acidity scale measurements indicate that H(CHB11Cl11) is the strongest pure Brønsted acid presently known, surpassing triflic and fluorosulfuric acid. Nevertheless, it is also an extremely gentle acid--because its conjugate base engages in so little chemistry. Carborane acids separate protic acidity from anion nucleophilicity and destructive oxidative capacity in the conjugate base, to a degree not previously achieved. As a result, many long-sought, highly acidic, reactive cations such as protonated benzene (C6H7+), protonated C60(HC60+), tertiary carbocations (R3C+), vinyl cations (R2C=C(+)-R), silylium ions (R3Si+) and discrete hydronium ions (H3O+, H5O2+ etc.) can be readily isolated as carborane salts and characterized at room temperature by X-ray crystallography.

  13. Photo-fragmentation of the closo-carboranes Part 1: Energetics of Decomposition

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    Kilcoyne, Arthur L; Feng, Danqin; Liu, Jing; Hitchcock, Adam P.; Kilcoyne, A.L. David; Tyliszczak, Tolek; Riehs, Norman F.; R& #252; hl, Eckart; Bozek, John D.; McIlroy, David; Dowben, Peter A.


    The ionic fragmentation following B 1s and C 1s excitation of three isomeric carborane cage compounds [closo-dicarbadodecaboranes: orthocarborane (1,2-C2B10H12), metacarborane (1,7-C2B10H12), and paracarborane (1,12-C2B10H12)], is compared with the energetics of decomposition. The fragmentation yields for all three molecules are quite similar. Thermodynamic cycles are constructed for neutral and ionic species in an attempt to systemically characterize single ion closo-carborane creation and fragmentation processes. Lower energy decomposition processes are favored. Among the ionic species, the photon induced decomposition isdominated by BH+ and BH2+ fragment loss. Changes in ion yield associated with core to bound excitations are observed.

  14. Novel axially carborane-cage substituted silicon phthalocyanine photosensitizer; synthesis, characterization and photophysicochemical properties (United States)

    Atmaca, Göknur Yaşa; Dizman, Cemil; Eren, Tarık; Erdoğmuş, Ali


    The novel axially dicarborane substituted silicon (IV) (SiPc-DC) phthalocyanine was synthesized by treating silicon phthalocyanine dichloride SiPc(Cl)2 (SiPc) with o-Carborane monool. The compound was characterized by mass spectrometry, UV-Vis, FT-IR, 1H and 11B Nuclear Magnetic Resonance Spectroscopy (NMR). Spectral, photophysical (fluorescence quantum yield) and photochemical (singlet oxygen (ΦΔ) and photodegradation quantum yield (Φd)) properties of the complex were reported in different solutions (Dimethyl sulfoxide (DMSO), Dimethylformamide (DMF) and Toluene). The results of spectral measurements showed that both SiPc and carborane cage can have potential to be used as sensitizers in photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) by their singlet oxygen efficiencies (ΦΔ = 0.41, 0.39).

  15. Computational study of the structural and vibrational properties of ten and twelve vertex closo-carboranes

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    Salam, A.; Deleuze, M.S.; Francois, J.-P


    Calculations using ab initio Hartree-Fock and Density Functional theories, the latter employing the B3LYP functional, in combination with a number of large standard basis sets ranging from 6-31G** to cc-pVDZ, have been performed on a series of ten and twelve vertex closo-carborane isomer species. Results obtained for optimized structural parameters and molecular properties are presented for 1,2-, 1,6- and 1,10-C{sub 2}B{sub 8}H{sub 10} and 1,2-, 1,7- and 1,12-C{sub 2}B{sub 10}H{sub 12} and compared, where possible, with both earlier theoretical data and experiment. Irrespective of the model chemistry chosen, the para-isomer in each class of carborane cluster is found to be the most stable species, corresponding to a structure in which the cage carbon atoms are positioned at diametrically opposed ends of the respective polyhedron. Boron-hydrogen and carbon-hydrogen bond lengths are found to change little on going from isomers of one particular cage size to another, supporting analogous conclusions previously established for small closo-carborane cages possessing five, six and seven vertices. The calculated vibrational spectra of the isomers of both decacarborane and dodecacarborane are seen to be similar to each other and reflect a high degree of rigidity within each cluster. Key polyhedral skeletal breathing modes along with characteristic boron-hydrogen and carbon-hydrogen stretching frequencies are identified in the spectra and compared with experiment. Thermochemical data relating to each species are also analyzed.

  16. Manipulation of phosphorescence efficiency of cyclometalated iridium complexes by substituted o-carboranes. (United States)

    Lee, Young Hoon; Park, Jihyun; Jo, Song-Jin; Kim, Miyoung; Lee, Junseong; Lee, Sang Uck; Lee, Min Hyung


    A series of [(C^N)2 Ir(acac)] complexes [{5-(2-R-CB)ppy}2 Ir(acac)] (3 a-3 g; acac=acetylacetonate, CB=o-carboran-1-yl, ppy=2-phenylpyridine; R=H (3 a), Me (3 b), iPr (3 c), iBu (3 d), Ph (3 e), CF3 C6 H4 (3 f), C6 F5 (3 g)) with various 2-R-substituted o-carboranes at the 5-position in the phenyl ring of the ppy ligand were prepared. X-ray diffraction studies revealed that the carboranyl CC bond length increases with increasing steric and electron-withdrawing effects from the 2-R substituents. Although the absorption and emission wavelengths of the complexes are almost invariant to the change of 2-R group, the phosphorescence quantum efficiency varies from highly emissive (ΦPL ≈0.80 for R=H, alkyl) to poorly emissive (R=aryl) depending on the 2-R group and the polarity of the medium. Theoretical studies suggest that 1) the almost nonemissive nature of the 2-aryl-substituted complexes is mainly attributable to the large contribution to the LUMO in the S1 excited state from an o-carborane unit and 2) the variation in the CC bond length between the S0 and T1 state structures increases with increasing steric (2-alkyl) and electronic effects (2-aryl) of the 2-R substituent and the polarity of the solvent. The solution-processed electroluminescence (EL) devices that incorporated 3 b and 3 d as emitters displayed higher performance than the device based on the parent [(ppy)2 Ir(acac)] complex. Along with the high phosphorescence efficiency, the bulkiness of the 2-R-o-carborane unit is shown to play an important role in improving device performance.

  17. Syntheses and Characterization of Half—Sandwich Zirconium Complexes with Dichalcogenolate o—Carborane Ligands

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    于晓燕; 金国新; 胡宁海


    Metallocene complex Cp2ttZrCl2(Cptt=η5-1,3-tBu2C5H3)(1)has been prepared from the reaction of LiCptt with ZrCl4 in good yield.Reactions of 1 with dilithium dichalcogenolate o-carboranes afforded new type of half-sandwich compounds with dichalcogenolate o-carboranyl ligands,[Li(THF)4][CpttZr(E2C2B10H10)2](E=S,2a;E=Se,2b)in which only one cyclopentadienyl ring ligand existed.Complexes 1 and 2a were structurally characterized by X-ray analyses.In complex 2a,the Zr(IV)ion is η5-bound to one 1,3-ditert-cyclopentadienyl ring and σ-bound to four μ2-sulfur atoms of two dithio-carboranes.the zirconium atom and four sulfur atoms form a distorted pyramid.The coordination sphere around the zirconium atom resembles in a piano stool structure with four legs of sulfur stoms and the fulcrum at the zirconium stom.

  18. A new approach to the synthesis of functional derivatives of nido-carborane: alkylation of [9-MeS-nido-7,8-C2B9H11]⁻. (United States)

    Zakharova, Maria V; Sivaev, Igor B; Anufriev, Sergey A; Timofeev, Sergey V; Suponitsky, Kyrill Yu; Godovikov, Ivan A; Bregadze, Vladimir I


    A series of asymmetrically substituted sulfonium derivatives of nido-carborane [9-R(Me)S-nido-7,8-C2B9H11] (R = Et, Pr, Bu, Bn, CH=CH2, CH2CH=CH2, CH2C≡CH, CH=C=CH2) were prepared by alkylation of the 9-methylthio-nido-7,8-carborane. The synthesized compounds are the first examples of diastereomers combining nido-carborane and sulfonium chiral centers.

  19. Photofragmentation of the closo-carboranes part II: VUV assisted dehydrogenation in the closo-carboranes and semiconducting B10C2H(x) films. (United States)

    Rühl, Eckart; Riehs, Norman F; Behera, Swayambhu; Wilks, Justin; Liu, Jing; Jochims, H-W; Caruso, Anthony N; Boag, Neil M; Kelber, Jeffry A; Dowben, Peter A


    The dehydrogenation of semiconducting boron carbide (B(10)C(2)H(x)) films as well as the three closo-carborane isomers of dicarbadodecaborane (C(2)B(10)H(12)) and two isomers of the corresponding closo-phosphacarborane (PCB(10)H(11)) all appear to be very similar. Photoionization mass spectrometry studies at near-threshold gas phase photoionization indicate that the preferred pathway for dissociation of the parent cation species (C(2)B(10)H(10)(+) or PCB(10)H(9)(+)) is, in all cases, the loss of H(2). Ab initio density functional theory (DFT) calculations indicate that energetically preferred sites for exopolyhedral hydrogen (B-H) bond dissociation are in all cases at B atoms opposite the C atoms in the parent cage molecule. The site of photodissociation of hydrogen from semiconducting boron carbide (B(10)C(2)H(x)) films, fabricated by plasma-enhanced chemical vapor deposition, is a cage boron atom that can bond to nitrogen upon exposure to VUV light in the presence of NH(3). Shifts in core level binding energies due to nitrogen bond formation indicate that B-N bond formation occurs only at B atoms bound to other boron atoms (B-B sites) and not at B-C sites or at C sites, in agreement with gas phase results.

  20. Precious metal carborane polymer nanoparticles: characterisation of micellar formulations and anticancer activity. (United States)

    Barry, Nicolas P E; Pitto-Barry, Anaïs; Romero-Canelón, Isolda; Tran, Johanna; Soldevila-Barreda, Joan J; Hands-Portman, Ian; Smith, Corinne J; Kirby, Nigel; Dove, Andrew P; O'Reilly, Rachel K; Sadler, Peter J


    We report the encapsulation of highly hydrophobic 16-electron organometallic ruthenium and osmium carborane complexes [Ru/Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolate)] ( and ) in Pluronic® triblock copolymer P123 core-shell micelles. The spherical nanoparticles and , dispersed in water, were characterized by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and synchrotron small-angle X-ray scattering (SAXS; diameter ca. 15 and 19 nm, respectively). Complexes and were highly active towards A2780 human ovarian cancer cells (IC(50) 0.17 and 2.50 μM, respectively) and the encapsulated complexes, as and nanoparticles, were less potent (IC(50) 6.69 μM and 117.5 μM, respectively), but more selective towards cancer cells compared to normal cells.

  1. Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues

    Directory of Open Access Journals (Sweden)

    Aleksandra Jankowiak


    Full Text Available The effect of the phenyl–alkyl connecting group on mesogenic properties of several series of isostructural compounds containing p-carborane (A and B, bicyclo[2.2.2]octane (C, and benzene (D was investigated using thermal and optical methods. Results demonstrated that mesophase stability in the series containing A–D follows the order (AlkCH2CH2– < (AlkOOC– < (AlkCH2O– < (AlkCOO–. Surprisingly, the connecting groups (AlkCH2CH2– and (AlkOOC– destabilize the mesophase significantly stronger for carboranes (A and B than for carbocyclic derivatives (C and D. Analysis indicates that this effect may have quadrupolar and conformational origin.

  2. Synthesis and biological evaluation of diaryl-substituted carboranes as inhibitors of hypoxia inducible factor (HIF)-1 transcriptional activity. (United States)

    Minegishi, Hidemitsu; Matsukawa, Takuya; Nakamura, Hiroyuki


    Diaromatic-substituted ortho- and meta-carboranes were synthesized as mimics of manassantin A. Among the carboranes synthesized, compounds 1 and 2 showed significant inhibition of hypoxia-induced HIF-1 transcriptional activity, with IC(50) values of 3.2 and 2.2 μM, respectively. Compounds 1 and 2 similarly suppressed hypoxia-induced HIF-1α accumulation in a concentration-dependent manner without affecting the expression level of HIF-1α mRNA. The hypoxia-induced accumulation and translocation of HIF-1α into nuclei were not observed in HeLa cells treated with compounds 1 and 2 by immunofluorescence analysis, revealing that the inhibition of hypoxia-induced HIF-1 transcriptional activity is induced by compounds 1 and 2 through a degradation pathway of the HIF-1α protein under hypoxic conditions.

  3. Plasma-enhanced chemical vapor deposition of ortho-carborane: structural insights and interaction with Cu overlayers. (United States)

    James, Robinson; Pasquale, Frank L; Kelber, Jeffry A


    X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS) are used to investigate the chemical and electronic structure of boron carbide films deposited from ortho-carborane precursors using plasma-enhanced chemical vapor deposition (PECVD), and the reactivity of PECVD films toward sputter-deposited Cu overlayers. The XPS data provide clear evidence of enhanced ortho-carborane reactivity with the substrate, and of extra-icosahedral boron and carbon species; these results differ from results for films formed by condensation and electron beam induced cross-linking of ortho-carborane (EBIC films). The UPS data show that the valence band maximum for PECVD films is ∼1.5 eV closer to the Fermi level than for EBIC films. The XPS data also indicate that PECVD films are resistant to thermally-stimulated diffusion of Cu at temperatures up to 1000 K in UHV, in direct contrast to recently reported results, but important for applications in neutron detection and in microelectronics.

  4. Effect of meta-carborane on segmental dynamics in a bimodal Poly(dimethylsiloxane) network

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    Lewicki, J; Maxwell, R S; Patel, M; Herberg, J; Swain, A C; Liggat, J; Pethrick, R


    Bimodal networks of polydimethylsiloxane (PDMS) filled with varying amounts of icosahedral meta-carborane (m-CB) have been developed and characterized by broadband dielectric spectroscopy (BDS) and static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR). Both BDS and MQ NMR showed evidence for a decrease in the polymer chain dynamics. BDS spectra quantified a normal-mode relaxation near 40 Hz at 40 C. The frequency maximum observed for filled samples decreased with increasing m-CB content until contents greater than 5 wt. %. The width of the relaxation spectrum increased with the addition of small quantities of filler and decreased with filler contents greater that 5 wt. %. Agglomeration effects were observed at loadings greater than 5 wt % as manifest by the onset of low frequency Maxwell-Wagner-Sillars (MWS) processes. The MQ NMR data allowed the characterization of distributions of the residual dipolar couplings, <{Omega}{sub d}> and thus in the dynamic order parameter, Sb, consistent with the bimodal network architecture expected from the synthesis protocol used. Upon addition of less than 10 wt.% m-CB filler, the mean <{Omega}{sub d}> for the longer chains increased by 46% and the width of the distribution increased by 33%. The mean <{Omega}{sub d}> for the shorter chains increased by much less, indicative of preferential dispersion of the filler particles in the long chain domains of the network structure. We conclude that the mechanism of reinforcement is likely a free volume space filling at low loadings transitioning to complex molecular filler and polymer chain interaction phenomena at higher loadings.

  5. Camouflaged carborarods derived from B-permethyl-1,12-diethynyl-para- and B-octamethyl-1,7-diethylnyl-meta-carborane modules. (United States)

    Herzog, Axel; Jalisatgi, Satish S; Knobler, Carolyn B; Wedge, Timothy J; Hawthorne, M Frederick


    Rigid camouflaged carborarods constructed from the corresponding C,C'-diethynyl derivatives of B-decamethyl-1,12-dicarbadodecaborane(12) (6) and B-octamethyl-1,7-dicarbadodecaborane(12) (48) have been synthesized by largely conventional organic transformations. These carborarods are the longest discrete rod species available by this method in which B-methylated p-carborane and m-carborane cages are linked through their carbon vertices by using butadiynylene moieties. They exhibit enhanced solubility in common organic solvents relative to all other presently known carborane-based rigid-rod molecules. The oxidative coupling of bis(ethynyl) derivatives of 6 generates oligomers containing, on average, 16 carborane modules. The structural characterization of the corresponding dimeric species revealed that the carborarods possess a sinusoidal chain distortion in the solid state. The stereoelectronic properties of these and related model carborarods were evaluated by using molecular dimensions as a monitor for the comparison of computational and experimental methods. In addition, the effect of exhaustive B-methylation of 12- and 10-vertex para-carborane cages in a series of model C,C'-diethynyl derivatives was similarly investigated by computational and structural studies. As expected, a correlation of intercage C--C bond lengths with cage size was observed and was attributed to hybridization effects. B-Permethylation had no significant structural effect with either 10- or 12-vertex cage derivatives. Relative to unsubstituted compounds, thermal and chemical stabilities of B-permethylated derivatives were increased through the operation of a steric "bumper-car" process, and solubilities in organic solvents were enhanced. The formation of linear, sterically encumbered platina-carborarods using ethynyl derivatives of 6 as precursors is described.

  6. Carborane-Based Carbonic Anhydrase Inhibitors: Insight into CAII/CAIX Specificity from a High-Resolution Crystal Structure, Modeling, and Quantum Chemical Calculations

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    Pavel Mader


    Full Text Available Carborane-based compounds are promising lead structures for development of inhibitors of carbonic anhydrases (CAs. Here, we report structural and computational analysis applicable to structure-based design of carborane compounds with selectivity toward the cancer-specific CAIX isoenzyme. We determined the crystal structure of CAII in complex with 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane at 1.0 Å resolution and used this structure to model the 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane interactions with CAIX. A virtual glycine scan revealed the contributions of individual residues to the energy of binding of 1-methylenesulfamide-1,2-dicarba-closo-dodecaborane to CAII and CAIX, respectively.

  7. Structure and second-order NLO property of the molecules bridged through n-vertex bis-substituted carborane (n=5, 6, 7)

    Institute of Scientific and Technical Information of China (English)


    Density functional theory (DFT) B3LYP at 6-31G* level is employed to optimize the structures of the molecules bridged through n-vertex bis-substituted carborane (n=5, 6, 7) and combined with finite field (FF) formalism to calculate the second-order NLO properties. The results indicate that the structures of n-vertex bis-substituted carborane (n=5, 6, 7) are changed due to bridged donor and acceptor moieties. The distances between two C atoms are becoming longer. And the stability and dipole moment are influenced by changing substituted positions of C atoms. The isomers with the substituents connecting with C atoms of lower coordination number have better stability and larger values of polarizability. One-dimensional structure of the molecules bridged through n-vertex bis-substituted carborane (n=5, 6, 7) is in favor of intramolecular charge-transfer. Meanwhile, the isomer with a larger change of dipole moment has larger value of second-order NLO properties during the charge-transfer process.

  8. Synthesis, Structure and Characterization of a Novel Asymmetrical Half-sandwich Binuclear Iron Carborane Complex [η5-C5H3(t-Bu)2]2Fe2(CO)3Se2C2B10H10

    Institute of Scientific and Technical Information of China (English)


    Halfsandwich iron dicarbonyl complex [η5-C5H3(t-Bu)2]Fe(CO)2Cl(1) reacts with 1, 2-dilithium diseleno carborane Li2Se2C2B10H10(2) to give a binuclear iron carborane complex [η5-C5H3(t-Bu)2]2Fe2(CO)3*Se2C2B10H10(3). The X-ray diffraction analysis of complex 3 reveals that one of the iron atoms is chiral.

  9. Ruthenium-catalyzed metathesis reactions of ortho- and meta-dialkenyl-carboranes: efficient ring-closing and acyclic diene polymerization reactions. (United States)

    Guron, Marta; Wei, Xiaolan; Carroll, Patrick J; Sneddon, Larry G


    The ruthenium-catalyzed metathesis reactions of dialkenyl-substituted ortho- and meta-carboranes provide excellent routes to both cyclic-substituted o-carboranes and new types of main-chain m-carborane polymers. The adjacent positions of the two olefins in the 1,2-(alkenyl)(2)-o-carboranes strongly favor the formation of ring-closed (RCM) products with the reactions of 1,2-(CH(2)=CHCH(2))(2)-1,2-C(2)B(10)H(10) (1), 1,2-(CH(2)=CH(CH(2))(3)CH(2))(2)-1,2-C(2)B(10)H(10) (2), 1,2-(CH(2)=CHSiMe(2))(2)-1,2-C(2)B(10)H(10) (3), 1,2-(CH(2)=CHCH(2)SiMe(2))(2)-1,2-C(2)B(10)H(10) (4), and 1,2-[CH(2)=CH(CH(2))(4)SiMe(2)](2)-1,2-C(2)B(10)H(10) (5) affording 1,2-(-CH(2)CH=CHCH(2)-)-C(2)B(10)H(10) (10), 1,2-[-CH(2)(CH(2))(3)CH=CH(CH(2))(3)CH(2)-]-1,2-C(2)B(10)H(10) (11), 1,2-[-SiMe(2)CH=CHSiMe(2)-]-1,2-C(2)B(10)H(10) (12), 1,2-[-SiMe(2)CH(2)CH=CHCH(2)SMe(2)-]-C(2)B(10)H(10) (13), and 1,2-[-SiMe(2)(CH(2))(4)CH=CH(CH(2))(4)SiMe(2)-]-C(2)B(10)H(10) (14), respectively, in 72-97% yields. On the other hand, the reaction of 1,2-(CH(2)-CHCH(2)OC(=O))(2)-1,2-C(2)B(10)H(10) (6) gave cyclo-[1,2-(1',8'-C(=O)OCH(2)CH=CHCH(2)OC(=O))-1,2-C(2)B(10)H(10)](2) (15a) and polymer 15b resulting from intermolecular metathesis reactions. The nonadjacent positions of the alkenyl groups in the 1,7-(alkenyl)(2)-m-carboranes, 1,7-(CH(2)=CHCH(2))(2)-1,7-C(2)B(10)H(10) (7), 1,7-(CH(2)=CH(CH(2))(3)CH(2))(2)-1,7-C(2)B(10)H(10) (8), and 1,7-(CH(2)=CHCH(2)SiMe(2))(2)-1,7-C(2)B(10)H(10) (9), disfavor the formation of RCM products, and in these cases, acyclic diene metathesis polymerizations (ADMET) produced new types of main chain m-carborane polymers. The structures of 3, 9, 11, 12, 13, and 15a were crystallographically confirmed.

  10. Luminescent properties and structure of multicomponent naphthalene-{beta}-cyclodextrin complexes. 1. Effect of adding third parties, o-carborane or/and adamantane

    Energy Technology Data Exchange (ETDEWEB)

    Nazarov, Valery B. [Institute of Problems of Chemical Physics of Russian Academy of Sciences, 142432 Moscow region, Chernogolovka (Russian Federation); Avakyan, Vitaly G., E-mail: [Photochemistry Center of Russian Academy of Sciences, 119421 Moscow, Novatorov 7a (Russian Federation); Rudyak, Vladimir Y.; Alfimov, Michail V. [Photochemistry Center of Russian Academy of Sciences, 119421 Moscow, Novatorov 7a (Russian Federation); Vershinnikova, Tatiana G. [Institute of Problems of Chemical Physics of Russian Academy of Sciences, 142432 Moscow region, Chernogolovka (Russian Federation)


    Luminescence spectra of water solution of {beta}-cyclodextrin ({beta}-CD) inclusion complexes with naphthalene have been studied in the presence of carcass compounds (CC), adamantane and ocarborane, added in solution as the third parties. It was observed that the CC structure completely determines luminescence type displayed by the three-component complex. Adding adamantane to the solution leads to the disappearance of the spontaneous excimer fluorescence observed usually along with a monomer fluorescence of naphthalene and the appearance of the long lived phosphorescence at room temperature. At the same time, introducing o-carborane in solution of {beta}-CD inclusion complexes with naphthalene results in the dramatic growth of intensity of the excimer band at the expense of lowering intensity of monomer fluorescence. These phenomena were explained using results of the quantum-chemical calculation of the structure and complexation energies at the semi-empirical PM3 and DFT levels of theory. - Highlights: > Structure of carcass compounds determines luminescence types for naphthalene - betaCD complex. > Adding o-carborane leads to the growth of excimer fluorescence at low naphthalene concentrations. > Adding adamantane leads to the room temperature phosphorescence without deoxygenation.

  11. Microwave-assisted synthesis of tricarbonyl rhenacarboranes: steric and electronic effects on the 1,2 --> 1,7 carborane cage isomerization. (United States)

    Armstrong, Andrea F; Valliant, John F


    A series of tricarbonyl rhenacarboranes {[M][Re(CO)3(RR'C2B9H9)]} (M = Na, K) were synthesized in water using microwave radiation with reaction times of less than 15 min. The novel complexes were isolated in good yields (57-94%) as either 3,1,2-(R = H: R' = CH2Pyr 6; R' = CH2Cy, 20) or 2,1,8-(R = H: R' = H, 4; R' = CH2PyrMe 12; R' = CH2PyrH, 13; R' = Pyr, 15; R' = Ph, 17; R = R' = Bn, 19) metallacarboranes and characterized by multinuclear (1H, 11B, 13C) and NOE NMR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray crystallography in the case of compounds 12 and 13. Carborane cage isomerization from the original 1,2 configuration to the 1,7 orientation occurred in cases where significant steric crowding was present at the metal center. Incorporation of a methylene spacer between the carborane cage and the six-membered ring as in 7 and 20 decreased steric strain such that the 3,1,2 configuration was maintained. Conversion of the 3,1,2 complex 6 to the 2,1,8 isomers 12 and 13 takes place at room temperature upon methylation or protonation of the pyridyl ring, indicating that electronic effects also play a significant role in the isomerization process.

  12. Carborane-containing metalloporphyrins for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Michiko; Joel, D.D.; Nawrocky, M.M.; Micca, P.L. [and others


    For BNCT of malignant brain tumors, it is crucial that there be relatively high boron concentrations in tumor compared with normal tissues within the neutron-irradiated treatment volume. Fairchild and Bond estimated that major advances in BNCT should be possible if ratios of {sup 10}B concentrations in tumor to those in normal tissue (e.g. brain and blood) were at least 5: 1. Given that the only current boron carrier being tested clinically in the U.S., p-boronophenyl-alanine[BPA], yields tumor blood and tumor brain ratios of about 3:1, the criteria for new boronated compounds should be to at least match these ratios and maintain tumor boron concentrations greater than 30 {mu}g B/g. Although previously tested boronated porphyrins have not only matched but surpassed these ratios, it was at a cost of greater toxicity. Chemical and hematological assays of blood analytes; showed marked thrombocytopenia, a decrease to about one-tenth the normal concentration of platelets circulating in the blood, in addition to abnormalities in concentrations of circulating enzymes, that indicated liver toxicity. The physical appearance and behavior of the affected mice were different from those of mice injected with solvent only. Although thrombocytopenia and other toxic effects had disappeared after a few days, previously tested porphyrins would not be safe to infuse into patients for BNCT of potentially hemorrhagic malignant tumors in the brain such as glioblastoma multiforme and metastatic melanoma. We synthesized a different boronated porphyrin, tetracarboranylphenylporphyrin, [TCP] and inserted nickel, copper, or manganese into its coordination center. Biological studies of NiTCP in mice and of CuTCP in rats show that these compounds elicit little or no toxicity when given at potentially therapeutic doses.

  13. The Crown Ether Promoted Base Degradation of p-Carborane. (United States)


    containing a magnetic stirring bar. The flask was fitted with a condenser and the system flushed with nitrogen for 15 min. Deoxygenated ethanol (100 ml) was...472 Attn: CRD-AA-IP 800 North Quincy Street P.O. Box 1211 Arlington, Virginia 22217 2 Research Triangle Park, N.C. 27709 ONR Branch Office Naval Ocean ...21401 Washington, D.C. 20360 1 Naval Ocean Systems Center Defense Documentation Center Attn: Dr. S. Yamamoto, Marine Building 5, Cameron Station Sciences

  14. Carborane-Catalyzed Graphitization in Polyarylacetylene-Derived Carbon- Carbon Composites (United States)


    for The Aerospace Corporation by R. W Fillers, Principal Director, Mechanics and Materials Technology Center. P M. Propp was the project officer for...findings or conclusions. It is published only for the exchange and stimulation of ideas. Quang Bui, Lt, USAF Paul M. Propp , GM-14 MOlE Program Manager Wright

  15. Carborane-Based Metal-Organic Framework with High Methane and Hydrogen Storage Capacities (United States)


    NMR , HR -MS, elemental analysis), and crystallographic information files (CIF) for LH4, LEt4, and NU-135; PXRD, adsorption excess isotherms, BET...boron, MOF, metal?organic framework, coordination polymer , porous, hydrogen, methane Vaiva Krungleviciute, Daniel J. Clingerman, Joseph E. Mondloch...framework, coordination polymer , porous, hydrogen, methane ■ INTRODUCTION Nanoporous materials such as metal−organic frameworks (MOFs) with tailorable pore

  16. Silver and Copper Complexes with closo-Polyhedral Borane, Carborane and Metallacarborane Anions: Synthesis and X-ray Structure

    Directory of Open Access Journals (Sweden)

    Varvara V. Avdeeva


    Full Text Available Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10]−, carba-closo-dodecaborate [CB11H12]−, and cobalt bis(dicarbollide [3,3′-Co(1,2-C2B9H112]− anions and their derivatives, are reviewed. The complexes demonstrate a wide variety of structural types, relating to both the metal coordination environment and coordination modes of boron hydride anions. The latter can range from strong coordination via the polyhedron triangular face including formation of 3c-2e MHB bonds in the case of the [B10H10]2− dianion, the structure of which contains two four-coordinated boron atoms, to very weak M…H interactions with the hydride atoms in the case of bulky [3,3′-Co(1,2-C2B9H112]− monoanion.

  17. Carborane complexes of ruthenium(III): studies on thermal reaction chemistry and the catalyst design for atom transfer radical polymerization of methyl methacrylate. (United States)

    Grishin, Ivan D; D'yachihin, Dmitrii I; Piskunov, Alexander V; Dolgushin, Fedor M; Smol'yakov, Alexander F; Il'in, Mikhail M; Davankov, Vadim A; Chizhevsky, Igor T; Grishin, Dmitry F


    The heating of the 18-electron complex [3,3-(dppb)-3-H-3-Cl-closo-3,1,2-RuC(2)B(9)H(11)] (3) in benzene at 80 °C in the presence of a small amount of CCl(4) as initiator afforded paramagnetic 17-electron species [3,3-(dppb)-3-Cl-closo-3,1,2-RuC(2)B(9)H(11)] (4) along with minor amounts of two P-phenylene ortho-cycloboronated derivatives [3-Cl-3,3,8-{Ph(2)P(CH(2))(4)PPh-μ-(C(6)H(4)-ortho)}-closo-3,1,2-RuC(2)B(9)H(10)] (5) and [3,7-Cl(2)-3,3,8-{Ph(2)P(CH(2))(4)PPh-μ-(C(6)H(4)-ortho)}-closo-3,1,2-RuC(2)B(9)H(10)] (6) in total yield of ca. 80%. The heating of either 3 or 4 in toluene at 95 °C in the absence of CCl(4) led to the selective formation of 5, which was isolated in 64% and 46% yield, respectively. Thermolysis of 3 at higher temperatures (boiling toluene, 110 °C) gives novel paramagnetic species [3-Cl-3,3,7,8-{Ph(2)P(CH(2))(4)P-μ-(C(6)H(4)-ortho)(2)}-closo-3,1,2-RuC(2)B(9)H(9)] (7) featuring bis(ortho-cycloboronation) of both P-phenyl groups at the same phosphorus atom of the ruthenium-bound dppb ligand. All new paramagnetic complexes 4-7, as well as starting diamagnetic species 3, were characterized by single-crystal X-ray diffraction and, in addition, by EPR spectroscopic studies of odd-electron complexes. Ruthenacarboranes 3-5 and 7 all display high efficiency as catalysts for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Complex 5 gave the best catalyst performance in terms of polydispersity; the PDI (M(w)/M(n)) of the polymer samples is as low as 1.15.

  18. Synthesis and Structure of Solvated Protons Incorporating Weakly Coordinating Anions. Precursors of Superacids

    Institute of Scientific and Technical Information of China (English)

    TSANG,Chi-Wing(曾志荣); YANG,Qing-Chuan(杨清传); MAK,Thomas C.W.(麦松威); XIE,Zuo-Wei(谢作伟)


    Six new solvated proton salts of highly halogenated carborane anions, [H(solvent)n] [carborane] (carborane = 1-R-CB11-Y5X-6 (R= H, Me; X, Y= Cl, Br, I), 1-H-CB9Br-9 ) were preparrf from the salt metathesis reaction of Ag(carborane)and HCl in high yields. Single-crystal X-ray analyses show that they are all discrete molecules in the solid-state. Tne mumher of the solvated molecules surrounding H+ ion can not be determined with the knowledge of the size and substituents of the carborane anions. Thnese salts provide convenient weighable sources of Brφnsted acid reagents having a wide range of acidities and good thermal stabilities. TGA results ubducate that the solvated molecules (water or organic molecules) in the catiobs [H(solvent)n]+ can be renoved under high temperature and high vacuum conditions to give superacidic mterials H(carborane) which can protonate olefin.

  19. Boron ion beam production with the supernanogan ECR ion source for the CERN BIO-LEIR facility

    CERN Document Server

    Stafford-Haworth, J; Scrivens, R; Toivanen, V; Röhrich, J


    To deliver B3+ ions for medical research the compounds decaborane and m-carborane were tested using the metal ions from volatile compounds (MIVOC) method with the Supernanogan 14.5 GHz ECR ion source. Using decaborane the source delivered less than 10 A intensity of B3+ and after operation large deposits of material were found inside the source. Using m-carborane 50 A of B3+ were delivered without support gas. For m-carborane, helium and oxygen support gasses were also tested, and the effects of different source tuning parameters are discussed. The average consumption of m-carborane was 0:1 mg/Ah over all operation.

  20. Microwave-assisted synthesis of 3,1,2- and 2,1,8-Re(I) and 99mTc(I)-metallocarborane complexes. (United States)

    Green, Andrew E C; Causey, Patrick W; Louie, Anika S; Armstrong, Andrea F; Harrington, Laura E; Valliant, John F


    Microwave heating was used to prepare eta5-rhenium carborane complexes in aqueous reaction media. For carboranes bearing sterically demanding substituents, isomerization of the cage from 3,1,2 to 2,1,8 derivatives occurred concomitantly with complexation. Microwave heating was equally effective at the tracer level using technetium-99m, affording access to a new class of synthons for designing novel molecular imaging agents.

  1. Electropolymerizable 2,2'-Carboranyldithiophenes. Structure-Property Investigations of the Corresponding Conducting Polymer Films by Electrochemistry, UV-Visible Spectroscopy and Conducting Probe Atomic Force Microscopy. (United States)

    Barrière, Frédéric; Fabre, Bruno; Hao, Erhong; Lejeune, Zorabel M; Hwang, Euiyong; Garno, Jayne C; Nesterov, Evgueni E; Vicente, M Graça H


    Carborane-functionalized conducting polymer films have been electrogenerated in dichloromethane from the anodic oxidation of ortho- (1), meta- (3) and para-carborane (4) isomers linked to two 2-thienyl units. The corresponding electrochemical response was characterized by a broad reversible redox system corresponding to the p-doping/undoping of the polythiophene backbone, the formal potential of which increased in the order poly(1) conductive domains of the electropolymerized films were evaluated by conducting probe AFM. The three polymers exhibit fairly similar morphological characteristics and a surface roughness of ~2 nm. Current-voltage (I-V) characteristics of conducting AFM tip-carborane polymer-ITO junctions showed that poly(1) had the highest conductivity.

  2. C,C'-bis(benzodiazaborolyl)dicarba-closo-dodecaboranes: synthesis, structures, photophysics and electrochemistry. (United States)

    Weber, Lothar; Kahlert, Jan; Brockhinke, Regina; Böhling, Lena; Halama, Johannes; Brockhinke, Andreas; Stammler, Hans-Georg; Neumann, Beate; Nervi, Carlo; Harder, Rachel A; Fox, Mark A


    Six new C,C'-bis(benzodiazaborolyl)dicarba-closo-dodecaboranes, 1,A-R2-1,A-C2B10H10, where R represents the group 2-(1,3-Et2-1,3,2-N2BC6H4) or 2-(1,3-Ph2-1,3,2-N2BC6H4) and A is 2, 7 or 12, were synthesized from o-, m-, and p-dicarbadodecaboranes (carboranes) by lithiation and subsequent treatment with the respective 2-bromo-1,3,2-benzodiazaboroles. UV-visible and fluorescence spectra of all carboranes display low energy charge transfer emissions. While such emissions with Stokes shifts between 17,330 and 21,290 cm(-1) are typical for C,C'-bis(aryl)-ortho-carboranes, the observed low-energy emissions with Stokes shifts between 8320 and 15,170 cm(-1) for the meta- and para-isomers are unusual as high-energy emissions are typical for meta- and para-dicarbadodecaboranes. Fluorescence quantum yields (φF) for the novel 1,7- and 1,12-bis(benzodiazaborolyl)-carboranes depend on the substituents at the nitrogen atoms of the heterocycle. Thus, the para-carborane with N-ethyl substituents 1,12-(1',3'-Et2-1',3',2'-N2BC6H4)2-1,12-C2B10H10 has a φF value of 41% in cyclohexane solution and only of 9% in the solid state, whereas the analogous 1,12-(1',3'-Ph2-1',3',2'-N2BC6H4)2-1,12-C2B10H10 shows quantum yields of 3% in cyclohexane solution and 72% in the solid state. X-ray crystallographic, computational and cyclic voltammetry studies for these carboranes are also presented.

  3. Acidities of closo-1-COOH-1,7-C2B10H11 and amino acids based on icosahedral carbaboranes. (United States)

    Dávalos, Juan Z; González, Javier; Ramos, Rocío; Hnyk, Drahomír; Holub, Josef; Santaballa, J Arturo; Canle-L, Moisés; Oliva, Josep M


    Carborane clusters are not found in Nature and are exclusively man-made. In this work we study, both experimentally and computationally, the gas-phase acidity (measured GA = 1325 kJ·mol(-1), computed GA = 1321 kJ·mol(-1)) and liquid-phase acidity (measured pKa = 2.00, computed pKa = 1.88) of the carborane acid closo-1-COOH-1,7-C2B10H11. The experimental gas-phase acidity was determined with electrospray tandem mass spectrometry (ESI/MS), by using the extended Cooks kinetic method (EKM). Given the similar spatial requirements of the title icosahedral cage and benzene and the known importance of aminoacids as a whole, such a study is extended, within an acid-base context, to corresponding ortho, meta, and para amino acids derived from icosahedral carborane cages, 1-COOH-n-NH2-1, n-R with {R = C2B10H10, n = 2, 7, 12}, and from benzene {R = C6H4, n = 2, 3, 4}. A remarkable difference is found between the proportion of neutral versus zwitterion structures in water for glycine and the carborane derived amino acids.

  4. Polyhedral Boranes: A Versatile Building Block for Nanoporous Materials (United States)

    Clingerman, Daniel Jon

    The studies described in this dissertation examine several new concepts related to polyhedral boranes and their applications towards the synthesis of novel nanoporous materials. The unique thermal and chemical robustness, rigidity, quasi-spherical geometry, and high boron content of polyhedral boranes are explored to generate materials not possible with typical organic synthons. Aside from the fundamental synthetic work, this work was also aimed at solving larger global issues such as energy storage and new routes to therapeutics. Chapter 2 highlights the discovery of the first highly porous carborane-based metal-organic framework, where the spherical nature of the carborane increases volumetric surface area without reducing pore volume. Chapter 3 examines the first tritopic carborane-based ligand and the stabilizing effect the rigid, sterically bulky carboranyl groups have on highly porous topologies not stable with typical organic ligands. Chapters 4 and 5 describe the use of polyhedral borane-based ligands as a means to influence and generate unexpected topologies. Lastly, chapter 6 explores using a simple carborane-based ligand that harnesses the power of coordination-driven assembly to rapidly generate a high boron-containing supramolecular cuboctahedron.

  5. New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications (United States)

    Guron, Marta

    There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly

  6. Development of a highly efficient burnable poison matrix material for cycle lifetime extension

    Energy Technology Data Exchange (ETDEWEB)

    Tulenko, J.S. [Florida Univ., 202 Nuclear Science Center, Gainesville, FL (United States); Baney, R.H.; Pressley, L. [Florida Univ., Gainesville, FL (United States)


    The University of Florida (UF) is carrying out basic research on a new class of thermally stable boron containing materials that from early indications appear to have special properties that will greatly enhance the performance of Burnable Poison Rod Assemblies (BPRA(tm)s) and address one of the major disadvantages of the use of boron shims. The new class of polymer materials, poly-acetylenic carbonyl-siloxane, termed ''Carborane'', were developed by Dr. T. Keller of the Naval Research Laboratory (NRL). Dr. T. Keller is cooperating in this research effort. Other classes of boron containing polymer materials are also under review. Displacement of water by the boron shims incurs an ''end of cycle reactivity penalty'' since at the end of cycle the moderator coefficient is strongly negative. ''Carborane'' has the property of being able to contain a tailored amount of boron while maintaining an extremely high hydrogen content, and at the same time being extremely stable to high temperatures and to neutron irradiation. Tests run by the NRL have shown that ''Carborane'' is stable to about 1000 C. The high hydrogen and carbon content contained in the ''Carborane'' Polymer offsets the large fuel cycle reactivity penalty which occurs with current generation BPRA(tm)s, as a result of the reactivity loss resulting from the BPRA(tm)s displacement of moderator water in the guide tubes of Pressurized Water Reactor (PWR) assemblies. Current generation BPRA utilize B{sub 4}C in an Al{sub 2}O{sub 3} matrix. In an attempt to minimize the reactivity penalty from water displacement, Westinghouse has developed a costly annular BPRA, called the Wet Annular Burnable Absorber (WABA) assembly. This burnable poison rod design reduces the moderator displacement by 22% by the use of a central annular water hole. The ''Carborane'' matrix proposed by the University of Florida

  7. Carboranyl oligonucleotides. 3. Biochemical properties of oligonucleotides containing 5-(o-carboranyl-l-yl)-2{prime}-deoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Lesnikowski, Z.J.; Fulcrand, G.; Lloyd, R.M. Jr. [Veterans Affairs Medical Center and Georgia Research Center for AIDS and HIV Infections, Decatur, GA (United States)]|[Emory Univ. School of Medicine, Atlanta, GA (United States)


    Boronated oligonucleotides are potential candidates for boron neutron capture therapy, antisense technology, and as tools in molecular biology. The biological properties of dodecathymidylic acids containing one or more 5-(o-carboran-l-yl)-2{prime}-deoxyuridine residues at different locations within the oligonucleotide chain were studied. 5-(o-carboran-l-yl)-2{prime}-deoxyuridine containing oligonucleotides manifested marked increased lipophilicity and resistance to 3{prime}- or 5{prime}-phosphodiesterases compared to the corresponding unmodified oligomer. They were substrates for T4 polynucleotide kinase and primers for Escherichia coli polymerase I and human immunodeficiency virus type 1 reverse transcriptase but not for human DNA polymerase {alpha} and {beta}. They also formed heteroduplexes that were substrates for E. coli RNase H, an essential property for antisense technology. These studies indicate that the carboranyl-containing oligonucleotides have desirable properties that need to be exploited further in the design of novel biopharmaceuticals. 33 refs., 2 figs., 1 tab.

  8. Boron Clusters as Highly Stable Magnesium-Battery Electrolytes**


    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S.; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W.


    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electro...

  9. Use of Li.sub.2[B.sub.12H.sub.12] salt to absorb water into polymers

    Energy Technology Data Exchange (ETDEWEB)

    Eastwood, Eric A.; Bowen, III, Daniel E.


    Methods of adjusting the properties of a composition are provided. The compositions comprise a polymer-containing matrix and a filler comprising a hygroscopic salt. Preferred such salts comprise a cage compound selected from the group consisting of borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer.

  10. Program and Abstracts, Boron Americas IX Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Feakes, Debra A.


    The Scientific and Technical Information (STI) submitted includes the final report and a collection of abstracts for the Ninth Boron in the Americas Conference which was held May 19-22, 2004, in San Marcos, Texas. The topics covered in the abstracts include: Application in Medicine, Application in Organic Synthesis and Catalysis, Boranes and Carboranes, Materials and Polymers, Metallaboranes and Metallacarboranes, Organoboron Compounds, Synthesis and Catalysis, and Theoretical Studies. Attendees represented researchers from government, industry, and academia.

  11. Conference on Graph Theory and Topology in Chemistry. (United States)


    pair of carbon heteroatoms in the polyhe- dral framework introduces the possibility of two or more positional isomers for each carborane. Processes that...have always been intrigued and stimulated by consideration of the structural causes of isomerism (the phenomenon where two chemical compounds with the... Synthesis of molecules capable of exhibiting topological stereoisomerism is one focus of our work resulting in the preparation of the first

  12. Molecular ion sources for low energy semiconductor ion implantation (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, A., E-mail: [Brookhaven National Laboratory, Upton, New York 11973 (United States); Gushenets, V. I.; Bugaev, A. S.; Oks, E. M.; Vizir, A.; Yushkov, G. Yu. [High Current Electronics Institute, Siberian Branch of Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Seleznev, D. N.; Kulevoy, T. V.; Kozlov, A.; Kropachev, G. N.; Kuibeda, R. P.; Minaev, S. [Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Dugin, S.; Alexeyenko, O. [State Scientific Center of the Russian Federation State Research Institute for Chemistry and Technology of Organoelement Compounds, Moscow (Russian Federation)


    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C{sub 4}H{sub 12}B{sub 10}O{sub 4}) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH{sub 3} = P{sub 4} + 6H{sub 2}; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P{sub 4}{sup +} ion beams were extracted. Results from devices and some additional concepts are described.

  13. Synthesis and 11C-Radiolabelling of 2-Carboranyl Benzothiazoles

    Directory of Open Access Journals (Sweden)

    Kiran B. Gona


    Full Text Available Dicarba-closo-dodecaboranes, commonly known as carboranes, possess unique physico-chemical properties and can be used as hydrophobic moieties during the design of new drugs or radiotracers. In this work, we report the synthesis of two analogues of 2-(4-aminophenylbenzothiazole (a compound that was found to elicit pronounced inhibitory effects against certain breast cancer cell lines in vitro in which the phenyl ring has been substituted by a m-carborane cage. Two different synthetic strategies have been used. For the preparation of 1-(9-amino-1,7-dicarba-closo-dodecaboran-1-yl-benzo-thiazole, the benzothiazole group was first introduced on one of the cluster carbon atoms of m-carborane and the amine group was further attached in three steps. For the synthesis of 1-(9-amino-1,7-dicarba-closo-dodecaboran-1-yl-6-hydroxybenzothiazole, iodination was performed before introducing the benzothiazole group, and the amino group was subsequently introduced in six steps. Both compounds were radiolabelled with carbon-11 using [11C]CH3OTf as the labelling agent. Radiolabelling yields and radiochemical purities achieved should enable subsequent in vitro and in vivo investigations.

  14. Characterization of a boron carbide-based polymer neutron sensor (United States)

    Tan, Chuting; James, Robinson; Dong, Bin; Driver, M. Sky; Kelber, Jeffry A.; Downing, Greg; Cao, Lei R.


    Boron is used widely in thin-film solid-state devices for neutron detection. The film thickness and boron concentration are important parameters that relate to a device's detection efficiency and capacitance. Neutron depth profiling was used to determine the film thicknesses and boron-concentration profiles of boron carbide-based polymers grown by plasma enhanced chemical vapor deposition (PECVD) of ortho-carborane (1,2-B10C2H12), resulting in a pure boron carbide film, or of meta-carborane (1,7-B10C2H12) and pyridine (C5H5N), resulting in a pyridine composite film, or of pyrimidine (C4H4N2) resulting in a pure pyrimidine film. The pure boron carbide film had a uniform surface appearance and a constant thickness of 250 nm, whereas the thickness of the composite film was 250-350 nm, measured at three different locations. In the meta-carborane and pyridine composite film the boron concentration was found to increase with depth, which correlated with X-ray photoelectron spectroscopy (XPS)-derived atomic ratios. A proton peak from 14N (n,p)14C reaction was observed in the pure pyrimidine film, indicating an additional neutron sensitivity to nonthermal neutrons from the N atoms in the pyrimidine.

  15. Electronically Active Cyclocarborane-Metal-Arene Assemblies (United States)


    Boron," Organometallics, 1990, 9, 1177. J. H. Davis, Jr., M. A. Benvenuto , and R. N. Grimes, "Organotransition-Metal Metalla- carboranes. 18. rY6, nl...3061. M. A. Benvenuto and R. N. Grimes, "Organotransition-Metal Metallacarboranes. 20. Bu 4N*F Fluoride-Catalyzed C-Si Bond Cleavage in Cp*Co(MeSi...Organometallic Synthesis", Chem. Rev. 1992, 92 251. M. A. Benvenuto and R. N. Grimes, "Organotransition-Metal Metallacarboranes. 28. Controlled Substitution at

  16. Doped Boron Carbide-Based Polymers: Fundamental Studies of a Novel Class of Materials for Enhanced Neutron Detection (United States)


    field of 0 T (black line), 0.1 T (purple line), 0.5 T (blue line), 0.8 T (green line) and 1 T (red line) for thin films of cross -linked ortho...aromatic precursors in UHV followed by electron bombardment to induce cross -linking, and (b) plasma-enhanced chemical vapor deposition (PECVD) of films...electronic structure. 3. Diode Detector Formation and testing: Diode structures were assembled from PECVD of ortho-carborane/aromatic films (p-type

  17. Extremes in Oxidizing Power, Acidity, and Basicity (United States)


    for the iodination of CB11H12! salts was greatly simplified and HCB11I11! is now easily available on a 10 g scale. The hope that its fluorination ...for the iodination of CB11H12! salts was greatly simplified and HCB11I11! is now easily available on a 10 g scale. The hope that its fluorination the starting anion to yield an iodonium salt carrying two carborane cages on an iodine atom. Report In the following, the salient results of our

  18. Numerical Sequence of Borane Series

    Directory of Open Access Journals (Sweden)

    Enos Masheija Kiremire


    Full Text Available A table of hydroborane families has been created. The table links boranes of different families(homologous series and members of the same family based on k number. The table is useful deducing straight away whether a borane( molecular formula is closo, nido or arachno or something else. The table also indicates that boranes are formed according to natural periodic function (arithmetical progression. The empirical formula utilized is extremely versatile, simple and based on the principle of Nobel gas configuration. It could be used in both simple and complex boranes and carboranes. The closo members which portray characteristic shapes also have characteristic k1 numbers.

  19. New insight in boron chemistry: Application in two-photon absorption (United States)

    Bolze, F.; Hayek, A.; Sun, X. H.; Baldeck, P. L.; Bourgogne, C.; Nicoud, J.-F.


    Two groups of one-dimensional (1D) boron containing two-photon absorbing fluorophores have been prepared and characterized. One group includes boron atoms incorporated in the conjugated or pseudo conjugated central core and the other contain a boron cluster as an acceptor group at one end of the fluorophores. Two boron containing central cores (with two boron atoms) have been explored: the cyclodiborazane and the pyrazabole moieties. The chosen boron cluster, p-carborane, contains 10 boron atoms. All the prepared fluorophores present high two-photon absorption cross-sections. Some water-soluble as well as lipophylic dyes have been prepared and used in bio-imaging.

  20. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    QIU ZaoZao; XIE ZuoWei


    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of icosahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  1. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)


    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of ico-sahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  2. First gaseous boronization during pulsed discharge cleaning (United States)

    Ko, J.; Den Hartog, D. J.; Goetz, J. A.; Weix, P. J.; Limbach, S. T.


    The first successful gaseous boronization during a pulsed discharge is reported. Sublimation of o-carborane (C2B10H12) combined with pulsed discharge plasmas with a repetition rate of 1 Hz is used to produce a hard boron-containing coating for reversed field pinch (RFP) plasmas in the Madison Symmetric Torus. X-ray photoelectron spectroscopy with Ar ion beam etching for silicon coupons installed at the plasma boundary shows about 60% boron concentration in the deposited layer. Both profilometer and scanning electron microscope analyses of the silicon coupons imply a strong toroidally non-uniform deposition depending on the location of the o-carborane injection. The layer thickness ranges from 50 to 300 nm. Ellipsometry calibrated with the profilometer results yields a refractive index of 2.2-2.3 for the films. The high refractive index implies that the coating is hard and has a well-ordered morphology. A reduction in wall recycling has consistently been observed after all boronization sessions. Comparison of the X-ray spectra in standard RFP plasmas before and after boronization indicates a slight decrease in the effective ionic charge.

  3. First gaseous boronization during pulsed discharge cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Ko, J., E-mail: [Department of Physics, University of Wisconsin, Madison, WI (United States); Den Hartog, D.J.; Goetz, J.A.; Weix, P.J.; Limbach, S.T. [Department of Physics, University of Wisconsin, Madison, WI (United States)


    The first successful gaseous boronization during a pulsed discharge is reported. Sublimation of o-carborane (C{sub 2}B{sub 10}H{sub 12}) combined with pulsed discharge plasmas with a repetition rate of 1 Hz is used to produce a hard boron-containing coating for reversed field pinch (RFP) plasmas in the Madison Symmetric Torus. X-ray photoelectron spectroscopy with Ar ion beam etching for silicon coupons installed at the plasma boundary shows about 60% boron concentration in the deposited layer. Both profilometer and scanning electron microscope analyses of the silicon coupons imply a strong toroidally non-uniform deposition depending on the location of the o-carborane injection. The layer thickness ranges from 50 to 300 nm. Ellipsometry calibrated with the profilometer results yields a refractive index of 2.2-2.3 for the films. The high refractive index implies that the coating is hard and has a well-ordered morphology. A reduction in wall recycling has consistently been observed after all boronization sessions. Comparison of the X-ray spectra in standard RFP plasmas before and after boronization indicates a slight decrease in the effective ionic charge.

  4. Inner-shell excitation and ionic fragmentation of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, A.P.; Tyliszczak, T. [McMaster Univ., Hamilton, Ontario (Canada); Cavell, R.G. [Univ. of Alberta, Edmonton (Canada)] [and others


    Inner-shell excitation and associated decay spectroscopies are site specific probes of electronic and geometrical structure and photoionization dynamics. X-ray absorption probes the geometric and electronic structure, while time-of-flight mass spectrometry with multi-coincidence detection provides information on the photofragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionised states is an efficient source of multiply charged ions. The charge separation and fragmentation of these species, studied by photoelectron-photoion-photoion coincidence (also called charge separation mass spectrometry) gives insights into bonding and electronic structure. In molecules, the dependence of the fragmentation process on the X-ray energy can reveal cases of site and/or state selective fragmentation. At the ALS the authors have examined the soft X-ray spectroscopy and ionic fragmentation of a number of molecules, including carboranes, silylenes, phosphorus halides, SF{sub 6} and CO{sub 2}. Their work is illustrated using results from the carborane and PF{sub 3} studies.

  5. 氟代十二顶点碳硼烷结构和非线性光学性质的理论研究%Theoretical Studies on the Structures and Second-order Nonlinear Optical Properties of 12-Vertex Fluorocarborane Molecules

    Institute of Scientific and Technical Information of China (English)

    方新燕; 王文勇; 王娇; 李晓倩; 宋洪娟; 仇永清


    采用密度泛函理论( DFT)方法,计算并分析了四氟取代十二顶点碳硼烷及其衍生物的结构和非线性光学( NLO)性质。结果表明,改变四氟碳硼烷取代基的共轭性或给吸电子能力,会使分子中碳硼笼原子间距离发生改变。碳硼烷取代基的给吸电子能力越强,其偶极矩越大。分子极化率随取代基共轭性和体积的增加而增大。引入强吸电子基或增加四氟碳硼烷取代基的共轭性,可使其二阶NLO响应明显增强。通过分析分子的电子光谱和对应的分子轨道组成可知,第一超极化率最大的分子4a'发生碳硼笼到并苯取代基的电荷转移。%The structures and second-order nonlinear optical( NLO) properties of tetrafluoro carborane and its derivatives were investigated with density functional theory method. The results indicate that elongating the conjugation or enhancing the strength of donor( D) and acceptor( A) groups affect the distances of the carbo-rane cage. Generally speaking, the dipole moment of molecule is determined by the D/A strengths, that is, the stronger D/A groups the larger dipole moment. Meanwhile, the polarizability of each molecule increases with the increasing of the conjugation and volume of substituents. Introducing the substituents with strong elec-tron-withdrawing abilities or promoting the conjugation of substituents can effectively improve the second-order NLO coefficients. Furthermore, from the analysis of electronic absorption spectrum and the corresponding mo-lecular orbit compositions, charge transfer pattern that comes from the carborane cage to the acene substituent illustrates the first hyperpolarizability value of molecule 4a'is the largest.

  6. Boron-Based (Nano-Materials: Fundamentals and Applications

    Directory of Open Access Journals (Sweden)

    Umit B. Demirci


    Full Text Available The boron (Z = 5 element is unique. Boron-based (nano-materials are equally unique. Accordingly, the present special issue is dedicated to crystalline boron-based (nano-materials and gathers a series of nine review and research articles dealing with different boron-based compounds. Boranes, borohydrides, polyhedral boranes and carboranes, boronate anions/ligands, boron nitride (hexagonal structure, and elemental boron are considered. Importantly, large sections are dedicated to fundamentals, with a special focus on crystal structures. The application potentials are widely discussed on the basis of the materials’ physical and chemical properties. It stands out that crystalline boron-based (nano-materials have many technological opportunities in fields such as energy storage, gas sorption (depollution, medicine, and optical and electronic devices. The present special issue is further evidence of the wealth of boron science, especially in terms of crystalline (nano-materials.

  7. Boron-Based Drug Design. (United States)

    Ban, Hyun Seung; Nakamura, Hiroyuki


    The use of the element boron, which is not generally observed in a living body, possesses a high potential for the discovery of new biological activity in pharmaceutical drug design. In this account, we describe our recent developments in boron-based drug design, including boronic acid containing protein tyrosine kinase inhibitors, proteasome inhibitors, and tubulin polymerization inhibitors, and ortho-carborane-containing proteasome activators, hypoxia-inducible factor 1 inhibitors, and topoisomerase inhibitors. Furthermore, we applied a closo-dodecaborate as a water-soluble moiety as well as a boron-10 source for the design of boron carriers in boron neutron capture therapy, such as boronated porphyrins and boron lipids for a liposomal boron delivery system.

  8. Boron Drug Delivery via Encapsulated Magnetic Nanocomposites: A New Approach for BNCT in Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Yinghuai Zhu


    Full Text Available Ortho-carborane cages have been successfully attached to modified magnetic nanoparticles via catalytic azide-alkyne cycloadditions between 1-R-2-butyl-Ortho-C2B10H10(R=Me,3;Ph,4 and propargyl group-enriched magnetic nanoparticles. A loading amount of 9.83 mmol boron atom/g starch-matrixed magnetic nanoparticles has been reached. The resulting nanocomposites have been found to be highly tumor-targeted vehicles under the influence of an external magnetic field (1.14T, yielding a high boron concentration of 51.4 μg/g tumor and ratios of around 10 : 1 tumor to normal tissues.

  9. B-Loaded Plastic Scintillator on the Base of Polystyrene

    CERN Document Server

    Brudanin, V B; Nemchenok, I B; Smolnikov, A A


    A method to produce polystyrene-based plastic scintillators with boron concentration from 0.38 to 5.0% of boron have been developed. o-Carborane was used as B-containing additive. The results of investigations of the optical, spectral and scintillation characteristics are presented and discussed. It is shown that 5% B-loaded scintillator has a light output as much as 70% relative to the unloaded one. High efficiency for thermal neutron registration achieved for produced samples makes it possible to use such scintillators in complex neutron high sensitive spectrometers. Measured level of radioactive contamination in this scintillation materials is good enough for using the B-loaded scintillators in the proposed large scale neutrino experiments.

  10. The local structure of transition metal doped semiconducting boron carbides

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jing; Dowben, P A [Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, Behlen Laboratory of Physics, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); Luo Guangfu; Mei Waining [Department of Physics, University of Nebraska at Omaha, Omaha, NE 68182-0266 (United States); Kizilkaya, Orhan [J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Hwy., Baton Rouge LA 70806 (United States); Shepherd, Eric D; Brand, J I [College of Engineering, and the Nebraska Center for Materials and Nanoscience, N209 Walter Scott Engineering Center, 17th and Vine Streets, University of Nebraska-Lincoln, Lincoln, NE 68588-0511 (United States)


    Transition metal doped boron carbides produced by plasma enhanced chemical vapour deposition of orthocarborane (closo-1,2-C{sub 2}B{sub 10}H{sub 12}) and 3d metal metallocenes were investigated by performing K-edge extended x-ray absorption fine structure and x-ray absorption near edge structure measurements. The 3d transition metal atom occupies one of the icosahedral boron or carbon atomic sites within the icosahedral cage. Good agreement was obtained between experiment and models for Mn, Fe and Co doping, based on the model structures of two adjoined vertex sharing carborane cages, each containing a transition metal. The local spin configurations of all the 3d transition metal doped boron carbides, Ti through Cu, are compared using cluster and/or icosahedral chain calculations, where the latter have periodic boundary conditions.

  11. Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick [Univ. of California, Los Angeles, CA (United States)


    amphiphilic unimolecular nanoparticles presenting several advantages: tunable size through functionalization and branching, spherical shape due to the icosahedral B122 core, promising water solubility resulting from degradation of all pendant closo-carborane groups to their hydrophilic nido anion substituents, and efficient boron delivery owing to the presence of 120 boron atoms which gives rise to a boron content as high as 40% by weight. Keeping the new objective in mind, we have focused on the design, synthesis and evaluation of new and very boron-rich closomer species. Additionally, progress has also been made toward the evaluation of a newly synthesized boron-rich lipid as a substitute for DSPC in bilayer construction, and the boron content of the resulting liposomes has been greatly enhanced. Related research involving the synthesis and self-assembly of carborane-containing amphiphiles has been systematically studied. Combined hydrophobic and hydrophilic properties of the single-chain amphiphiles allow their spontaneous self-assembly to form rods under a variety of variable conditions, such as concentration in the bilayer, carborane cage structure, chain-length, counterion identity, solvents, methods of preparation, and the ionic charge. On the other hand, the number of attached chains affects the self-assembly process. Particles having totally different shapes have been observed for dual-chain amphiphiles.

  12. Synthesis of single-molecule nanocars. (United States)

    Vives, Guillaume; Tour, James M


    p-carborane- and ruthenium-based wheels with greater solubility in organic solvents. Although fullerene wheels must be attached in the final synthetic step, p-carborane- and ruthenium-based wheels do not inhibit organometallic coupling reactions, which allows a more convergent synthesis of molecular machines. We also prepared functional nanotrucks for the transport of atoms and molecules, as well as self-assembling nanocars and nanotrains. Although engineering challenges such as movement over long distance and non-atomically flat surfaces remain, the greatest current research challenge is imaging. The detailed study of nanocars requires complementary single molecule imaging techniques such as STM, AFM, TEM, or single-molecule fluorescence microscopy. Further developments in engineering and synthesis could lead to enzyme-like manipulation and assembly of atoms and small molecules in nonbiological environments.

  13. Myths about the proton. The nature of H+ in condensed media. (United States)

    Reed, Christopher A


    Recent research has taught us that most protonated species are decidedly not well represented by a simple proton addition. What is the actual nature of the hydrogen ion (the "proton") when H(+), HA, H2A(+), and so forth are written in formulas, chemical equations, and acid catalyzed reactions? In condensed media, H(+) must be solvated and is nearly always dicoordinate, as illustrated by isolable bisdiethyletherate salts having H(OEt2)2(+) cations and weakly coordinating anions. Even carbocations such as protonated alkenes have significant C-H···anion hydrogen bonding that gives the active protons two-coordinate character. Hydrogen bonding is everywhere, particularly when acids are involved. In contrast to the normal, asymmetric O-H···O hydrogen bonding found in water, ice, and proteins, short, strong, low-barrier (SSLB) H-bonding commonly appears when strong acids are present. Unusually low frequency IR νOHO bands are a good indicator of SSLB H-bonds, and curiously, bands associated with group vibrations near H(+) in low-barrier H-bonding often disappear from the IR spectrum. Writing H3O(+) (the Eigen ion), as often appears in textbooks, might seem more realistic than H(+) for an ionized acid in water. However, this, too, is an unrealistic description of H(aq)(+). The dihydrated H(+) in the H5O2(+) cation (the Zundel ion) gets somewhat closer but still fails to rationalize all the experimental and computational data on H(aq)(+). Researchers do not understand the broad swath of IR absorption from H(aq)(+), known as the "continuous broad absorption" (cba). Theory has not reproduced the cba, but it appears to be the signature of delocalized protons whose motion is faster than the IR time scale. What does this mean for reaction mechanisms involving H(aq)(+)? For the past decade, the carborane acid H(CHB11Cl11) has been the strongest known Brønsted acid. (It is now surpassed by the fluorinated analogue H(CHB11F11).) Carborane acids are strong enough to protonate

  14. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples. (United States)

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K


    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology.


    Directory of Open Access Journals (Sweden)

    M. H. Alai et al.


    Full Text Available Carbon nanotubes are cylindrical carbon molecules have novel properties, making them potentially useful in many applications in nanotechnology, electronics, optics, and other fields of material science as well as potential uses in architectural fields. They have unique electronic, mechanical, optical and chemical properties that make them good candidates for a wide variety of applications, including drug transporters, new therapeutics, delivery systems and diagnostics. Their unique surface area, stiffness, strength and resilience have led to much excitement in the field of pharmacy. Nanotubes are categorized as single-walled nanotubes, multiple walled nanotubes. Various techniques have been developed to produce nanotubes in sizeable quantities, including arc discharge, laser ablation, chemical vapor deposition. They can pass through membranes, carrying therapeutic drugs, vaccines and nucleic acids deep into the cell to targets previously unreachable. Purification of the tubes can be divided into a couple of main techniques: oxidation, acid treatment, annealing, sonication, filtering and functionalization techniques. The main problem of insolubility in aqueous media has been solved by developing a synthetic protocol that allows highly water-soluble carbon NTs to be obtained. The modifications are done to improve efficiency of carbon nanotubes by formulating luminescent carbon nanotubes, ultrathin carbon nanoneedles, magnetically guided nanotubes. The application of carbon nanotube in tissue engineering, drug carrier release system, wound healing, in cancer treatment and as biosensor. Researchers have recently developed a new approach to Boron Neutron Capture Therapy in the treatment of cancer using substituted Carborane-Appended Water-Soluble single-wall carbon nanotubes.

  16. Synthesis and evaluation of boron folates for Boron-Neutron-Capture-Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Kettenbach, Kathrin; Schieferstein, Hanno; Grunewald, Catrin; Hampel, Gabriele; Schuetz, Christian L. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Iffland, Dorothee; Bings, Nicolas H. [Mainz Univ. (Germany). Inst. of Inorganic Chemistry and Analytical Chemistry; Reffert, Laura M. [Hannover Medical School (Germany). Radiopharmaceutical Chemistry; Ross, Tobias L. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Hannover Medical School (Germany). Radiopharmaceutical Chemistry


    Boron neutron capture therapy (BNCT) employs {sup 10}B-pharmaceuticals administered for the treatment of malignancies, and subsequently irradiated with thermal neutrons. So far, clinical established pharmaceuticals like boron phenylalanine (BPA) or sodium boron mercaptate (BSH) use imperfect (BPA) or passive (BSH) targeting for accumulation at target sites. Due to the need of a selective transportation of boron drugs into cancer cells and sparing healthy tissues, we combined the BNCT approach with the specific and effective folate receptor (FR) targeting concept. The FR is overexpressed on many human carcinomas and provides a selective and specific target for molecular imaging as well as for tumor therapy. We synthesized and characterized a carborane-folate as well as a BSH-folate to study their in vitro characteristics and their potential as new boron-carriers for BNCT. Uptake studies were carried out using human KB cells showing a significant increase of the boron content in cells and demonstrating the successful combination of active FR-targeting and BNCT.

  17. The local physical structure of amorphous hydrogenated boron carbide: insights from magic angle spinning solid-state NMR spectroscopy. (United States)

    Paquette, Michelle M; Li, Wenjing; Sky Driver, M; Karki, Sudarshan; Caruso, A N; Oyler, Nathan A


    Magic angle spinning solid-state nuclear magnetic resonance spectroscopy techniques are applied to the elucidation of the local physical structure of an intermediate product in the plasma-enhanced chemical vapour deposition of thin-film amorphous hydrogenated boron carbide (B(x)C:H(y)) from an orthocarborane precursor. Experimental chemical shifts are compared with theoretical shift predictions from ab initio calculations of model molecular compounds to assign atomic chemical environments, while Lee-Goldburg cross-polarization and heteronuclear recoupling experiments are used to confirm atomic connectivities. A model for the B(x)C:H(y) intermediate is proposed wherein the solid is dominated by predominantly hydrogenated carborane icosahedra that are lightly cross-linked via nonhydrogenated intraicosahedral B atoms, either directly through B-B bonds or through extraicosahedral hydrocarbon chains. While there is no clear evidence for extraicosahedral B aside from boron oxides, ∼40% of the C is found to exist as extraicosahedral hydrocarbon species that are intimately bound within the icosahedral network rather than in segregated phases.

  18. Reactions of a 16-electron Cp*Co half-sandwich complex containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand with alkynones HC≡C-C(O)R (R=OMe,Me,Ph)

    Institute of Scientific and Technical Information of China (English)

    GUOYIQIBAYI; Gulnisa


    The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH2 unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3-6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7-10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.

  19. Multidimensional potential of boron-containing molecules in functional materials

    Indian Academy of Sciences (India)

    Wolfgang Kaim; Narayan S Hosmane


    Boron-containing molecular systems have received much attention under theoretical aspects and from the side of synthetic organic chemistry. However, their potential for further applications such as optically interesting effects such as Non-Linear Optics (NLO), medical uses for Boron Neutron Capture Therapy (BNCT), or magnetism has been recognised only fairly recently. Molecular systems containing boron offer particular mechanisms to accommodate unpaired electrons which may result in stable radicals as spin-bearing materials. Among such materials are organoboron compounds in which the prototypical electron deficient (10B, 11B) boron vs. carbon centers can accept and help to delocalise added electrons in a 2-dimensionally conjugated system. Alternatively, oligoboron clusters B$_{n}$X$_{n}^{k}$ and the related carboranes or metallacarboranes are capable of adding or losing single electrons to form paramagnetic clusters with 3-dimensionally delocalised spin, according to combined experimental studies and quantum chemical calculations. The unique nuclear properties of 10B are of therapeutic value if their selective transport via appended carbon nanotubes, boron nanotubes, or magnetic nanoparticles can be effected.

  20. Synthesis and single-molecule imaging of highly mobile adamantane-wheeled nanocars. (United States)

    Chu, Pin-Lei E; Wang, Lin-Yung; Khatua, Saumyakanti; Kolomeisky, Anatoly B; Link, Stephan; Tour, James M


    The synthesis and single-molecule imaging of two inherently fluorescent nanocars equipped with adamantane wheels is reported. The nanocars were imaged using 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) as the chromophore, which was rigidly incorporated into the nanocar chassis via Sonogashira cross-coupling chemistry that permitted the synthesis of nanocars having different geometries. In particular, studied here were four- and three-wheeled nanocars with adamantane wheels. It was found that, for the four-wheeled nanocar, the percentage of moving nanocars and the diffusion constant show a significant improvement over p-carborane-wheeled nanocars with the same chassis. The three-wheeled nanocar showed only limited mobility due to its geometry. These results are consistent with a requisite wheel-like rolling motion. We furthermore developed a model that relates the percentage of moving nanocars in single-molecule experiments with the diffusion constant. The excellent agreement between the model and the new results presented here as well as previous single-molecule studies of fluorescent nanocars yields an improved understanding of motion in these molecular machines.

  1. Analysis of boron carbides' electronic structure (United States)

    Howard, Iris A.; Beckel, Charles L.


    The electronic properties of boron-rich icosahedral clusters were studied as a means of understanding the electronic structure of the icosahedral borides such as boron carbide. A lower bound was estimated on bipolaron formation energies in B12 and B11C icosahedra, and the associated distortions. While the magnitude of the distortion associated with bipolaron formation is similar in both cases, the calculated formation energies differ greatly, formation being much more favorable on B11C icosahedra. The stable positions of a divalent atom relative to an icosahedral borane was also investigated, with the result that a stable energy minimum was found when the atom is at the center of the borane, internal to the B12 cage. If incorporation of dopant atoms into B12 cages in icosahedral boride solids is feasible, novel materials might result. In addition, the normal modes of a B12H12 cluster, of the C2B10 cage in para-carborane, and of a B12 icosahedron of reduced (D sub 3d) symmetry, such as is found in the icosahedral borides, were calculated. The nature of these vibrational modes will be important in determining, for instance, the character of the electron-lattice coupling in the borides, and in analyzing the lattice contribution to the thermal conductivity.

  2. Tratamiento del cáncer por captura neutrónica de boro: Su aplicación al carcinoma indiferenciado de tiroides Boron neutron capture therapy applied to undifferentiated thyroid carcinoma

    Directory of Open Access Journals (Sweden)

    Mario A. Pisarev


    Full Text Available El cáncer indiferenciado de tiroides es un tumor muy agresivo, de muy mal pronóstico y sin tratamiento efectivo. La terapia por captura neutrónica de boro (BNCT podría ser una alternativa para el tratamiento de esta enfermedad. Se basa en la captación selectiva de boro por el tumor y su activación por un haz de neutrones. El boro activado libera un núcleo de litio-7 y una partícula alfa, las cuales tienen una alta transmisión linear de energía (linear energy transfer, LET y un alcance de 5-9 µm, destruyendo el tumor. En estudios previos hemos mostrado que la línea celular humana de cáncer indiferenciado de tiroides (ARO tiene una captación selectiva de borofenilalanina (10BPA tanto in vitro como después de ser implantada en ratones NIH nude. También demostramos en estos animales inyectados con BPA e irradiados con un haz de neutrones térmicos, un 100% de control sobre el crecimiento tumoral y un 50% de cura histológica. En trabajos posteriores mostramos que la porfirina 10BOPP tetrakis-carborane carboxylate ester de 2,4-bis-(a,b-dihydroxyethyl-deutero-porphyrin IX cuando es inyectada 5-7 días antes que el BPA se obtiene una concentración tumoral de boro de aproximadamente el doble que el BPA solo (45-38 ppm vs. 20 ppm. La posterior irradiación con neutrones mostró un 100% de remisión completa en animales con tumores cuyo volumen pre-tratamiento era de 50 mm³ o menor. Los perros padecen CIT espontáneo, con un comportamiento biológico similar al humano, y una captación selectiva de BPA, abriendo la posibilidad de su tratamiento por BNCT.Undifferentiated thyroid carcinoma (UTC is an aggressive tumor with a poor prognosis due to the lack of an effective treatment. Boron neutron capture therapy (BNCT is based on the selective uptake of boron by the tumor and its activation by a neutron beam, releasing lithium-7 and an alpha particle that will kill the tumor cells by their high linear energy transfer (LET. In previous

  3. Hydrogen bonding versus hyperconjugation in condensed-phase carbocations. (United States)

    Reed, Christopher A; Stoyanov, Evgenii S; Tham, Fook S


    Hyperconjugative stabilization of positive charge in tertiary carbocations is the textbook explanation for their stability and low frequency νCH bands in their IR spectra have long been taken as confirming evidence. While this is substantiated in the gas phase by the very close match of the IR spectrum of argon-tagged t-butyl cation with that calculated under C(s) symmetry, the situation in condensed phases is much less clear. The congruence of νCH(max) of t-Bu(+) in superacid media (2830 cm(-1)) with that in the gas phase (2834 cm(-1)) has recently been shown to be accidental. Rather, νCH(max) varies considerably as a function of counterion in a manner that reveals the presence of significant C-H···anion hydrogen bonding. This paper addresses the question of the relative importance of hyperconjugation versus H-bonding. We show by assigning IR spectra in the νCH region to specific C-H bonds in t-butyl cation that the low frequency νCH(max) band in the IR spectrum of t-butyl cation, long taken as direct evidence for hyperconjugation, appears to be due mostly to H-bonding. The appearance of similar low frequency νCH bands in the IR spectra of secondary alkyl carboranes such as i-Pr(CHB11Cl11), which have predominant sp(3) centres rather than sp(2) centres (and are therefore less supportive of hyperconjugation), also suggests the dominance of H-bonding over hyperconjugation.

  4. Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model. (United States)

    Heber, Elisa M; Hawthorne, M Frederick; Kueffer, Peter J; Garabalino, Marcela A; Thorp, Silvia I; Pozzi, Emiliano C C; Monti Hughes, Andrea; Maitz, Charles A; Jalisatgi, Satish S; Nigg, David W; Curotto, Paula; Trivillin, Verónica A; Schwint, Amanda E


    The application of boron neutron capture therapy (BNCT) mediated by liposomes containing (10)B-enriched polyhedral borane and carborane derivatives for the treatment of head and neck cancer in the hamster cheek pouch oral cancer model is presented. These liposomes are composed of an equimolar ratio of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] (MAC) in the bilayer membrane while encapsulating the hydrophilic species Na3[ae-B20H17NH3] (TAC) in the aqueous core. Unilamellar liposomes with a mean diameter of 83 nm were administered i.v. in hamsters. After 48 h, the boron concentration in tumors was 67 ± 16 ppm whereas the precancerous tissue contained 11 ± 6 ppm, and the tumor/normal pouch tissue boron concentration ratio was 10:1. Neutron irradiation giving a 5-Gy dose to precancerous tissue (corresponding to 21 Gy in tumor) resulted in an overall tumor response (OR) of 70% after a 4-wk posttreatment period. In contrast, the beam-only protocol gave an OR rate of only 28%. Once-repeated BNCT treatment with readministration of liposomes at an interval of 4, 6, or 8 wk resulted in OR rates of 70-88%, of which the complete response ranged from 37% to 52%. Because of the good therapeutic outcome, it was possible to extend the follow-up of BNCT treatment groups to 16 wk after the first treatment. No radiotoxicity to normal tissue was observed. A salient advantage of these liposomes was that only mild mucositis was observed in dose-limiting precancerous tissue with a sustained tumor response of 70-88%.

  5. Effect on Graphite Substrate to Formation of Boron Carbide/Carbon Composite Nanoropes%石墨基底对碳/碳化硼复合纳米绳形成的影响

    Institute of Scientific and Technical Information of China (English)

    马淑芳; 梁建; 赵君芙; 孙晓霞; 许并社


    利用邻碳硼烷(C2H12B10)作为反应原料,二茂铁(C10H10Fe)作为催化剂,通过化学气相沉积法在石墨基片上生长出一种新颖的碳化硼纳米绳.用X射线衍射仪分析纳米绳的相结构,用场发射扫描电子显微镜(FESEM)和高分辨透射电子显微镜(HRTEM)观察纳米绳的微观形貌和结构,结果发现纳米绳的中心部分是碳化硼纳米线,在线的表面有非晶碳绳结,故纳米绳为碳/碳化硼复合物.研究了绳状产物的生长机理,表明石墨基片对产物的形成有至关重要的作用.%A type of novel boron carbide nanoropes has been grown on the graphite substrate by chemical vapor deposition method. In this study, o-carborane(C2H12B10) powder was used as a precursor and ferrocene(C10H10Fe) as a catalyst. Phase, microstructures and components of these nanoropes were characterized by X-ray diffractometer (XRD), scan electron microscopy(SEM) and high-resolution transmission electron microscopy(HRTEM) as well as energy dispersive X-ray spectroscopy(EDS). It has been found that the boron carbide nanoropes have such a structure of a single crystal wire in the centre of ropes partially covered with amorphous carbon knots. Growth mechanism of boron carbide nanoropes was discussed. It has demonstrated that the substrate of graphite plays a significant role in the formation of nanoropes.

  6. Books Noted (United States)


    Combinatorial Chemistry and Molecular Diversity in Drug Discovery E. M. Gordon and J. F. Kerwin Jr. Wiley-Liss: New York, 1998. xxiv + 516 pp. ISBN 0-471-15518-7. 89.95. Advances in Atomic Spectroscopy, Volume 4 J. Sneddon. JAI: Stamford, CT, 1998. x + 232 pp. ISBN 0-7623-0342-5. 109.50. Organic Synthesis, Collective Volume IX J. P. Freeman, Ed. Wiley: New York, 1998. xxi + 840 pp. ISBN 0-471-24248-9. 89.95. Advances in Theoretically Interesting Molecules R. P. Thummel. JAI: Stamford, CT, 1998. x + 350 pp. ISBN 0-7623-00070-1. 109.50. Organic Syntheses, Volume 75 A. B. Smith III, Ed. Wiley: New York, 1998. xxxvi + 257 pp. ISBN 0-471-18372-5. 39.95. Teaching American Students, 2nd Revised Edition E. Sarksian. Harvard University Publishing: Cambridge, MA, 1997. 109 pp. ISBN 0966246802. 11.95. Advances in Photochemistry, Volume 24 D. C. Neckers, D. H. Volman, and G. Von Bunau. Wiley-Interscience: New York, 1998. ix + 352 pp. ISBN 0-471-28723-1. 95.00. Inorganic Synthesis, Volume 32 M. Y. Darensbourg. Wiley-Interscience: New York, 1998. xxiii + 331 pp. ISBN 0-471-24921-1. 80.00. The Borane, Carborane, Carbocation Continuum J. Casanova, Ed. Wiley-Interscience: New York, 1998. xxi + 437 pp. ISBN 0-471-18075-0. 89.95. Inorganic Reactions and Methods, Volume 14 J. J. Zuckerman and J. D. Atwood, Eds. Wiley-VCH: New York, 1998. xxiii + 688 pp. ISBN 0-471-19201-5. 250.00. Advances in Molecular Vibrations and Collision Dynamics, Volume 3 J. M. Bowman. JAI: Stamford, CT, 1998. xi + 460 pp. ISBN 1-55938-790-4. $109.50.

  7. Convection enhanced delivery of carboranylporphyrins for neutron capture therapy of brain tumors. (United States)

    Kawabata, Shinji; Yang, Weilian; Barth, Rolf F; Wu, Gong; Huo, Tianyao; Binns, Peter J; Riley, Kent J; Ongayi, Owendi; Gottumukkala, Vijay; Vicente, M Graça H


    Boron neutron capture therapy (BNCT) is based on the nuclear capture and fission reactions that occur when non-radioactive 10B is irradiated with low energy thermal neutrons to produce α-particles (10B[n,α] Li). Carboranylporphyrins are a class of substituted porphyrins containing multiple carborane clusters. Three of these compounds, designated H2TBP, H2TCP, and H2DCP, have been evaluated in the present study. The goals were two-fold. First, to determine their biodistribution following intracerebral (i.c.) administration by short term (30 min) convection enhanced delivery (CED) or sustained delivery over 24 h by Alzet™ osmotic pumps to F98 glioma bearing rats. Second, to determine the efficacy of H2TCP and H2TBP as boron delivery agents for BNCT in F98 glioma bearing rats. Tumor boron concentrations immediately after i.c. pump delivery were high and they remained so at 24 h. The corresponding normal brain concentrations were low and the blood and liver concentrations were undetectable. Based on these data, therapy studies were initiated at the Massachusetts Institute of Technology (MIT) Research Reactor (MITR) with H2TCP and H2TBP 24 h after CED or pump delivery. Mean survival times (MST) ± standard deviations of animals that had received H2TCP or H2TBP, followed by BNCT, were of 35 ± 4 and 44 ± 10 days, compared to 23 ± 3 and 27 ± 3 days, respectively, for untreated and irradiated controls. However, since the tumor boron concentrations of the carboranylporphyrins were 3-5× higher than intravenous (i.v.) boronophenylalanine (BPA), we had expected that the MSTs would have been greater. Histopathologic examination of brains of BNCT treated rats revealed that there were large numbers of porphyrin-laden macrophages, as well as extracellular accumulations of porphyrins, indicating that the seemingly high tumor boron concentrations did not represent the true tumor cellular uptake. Nevertheless, our data are the first to show that carboranyl porphyrins can be

  8. The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide (United States)

    Nordell, Bradley J.; Karki, Sudarshan; Nguyen, Thuong D.; Rulis, Paul; Caruso, A. N.; Purohit, Sudhaunshu S.; Li, Han; King, Sean W.; Dutta, Dhanadeep; Gidley, David; Lanford, William A.; Paquette, Michelle M.


    Because of its high electrical resistivity, low dielectric constant (κ), high thermal neutron capture cross section, and robust chemical, thermal, and mechanical properties, amorphous hydrogenated boron carbide (a-BxC:Hy) has garnered interest as a material for low-κ dielectric and solid-state neutron detection applications. Herein, we investigate the relationships between chemical structure (atomic concentration B, C, H, and O), physical/mechanical properties (density, porosity, hardness, and Young's modulus), electronic structure [band gap, Urbach energy (EU), and Tauc parameter (B1/2)], optical/dielectric properties (frequency-dependent dielectric constant), and electrical transport properties (resistivity and leakage current) through the analysis of a large series of a-BxC:Hy thin films grown by plasma-enhanced chemical vapor deposition from ortho-carborane. The resulting films exhibit a wide range of properties including H concentration from 10% to 45%, density from 0.9 to 2.3 g/cm3, Young's modulus from 10 to 340 GPa, band gap from 1.7 to 3.8 eV, Urbach energy from 0.1 to 0.7 eV, dielectric constant from 3.1 to 7.6, and electrical resistivity from 1010 to 1015 Ω cm. Hydrogen concentration is found to correlate directly with thin-film density, and both are used to map and explain the other material properties. Hardness and Young's modulus exhibit a direct power law relationship with density above ˜1.3 g/cm3 (or below ˜35% H), below which they plateau, providing evidence for a rigidity percolation threshold. An increase in band gap and decrease in dielectric constant with increasing H concentration are explained by a decrease in network connectivity as well as mass/electron density. An increase in disorder, as measured by the parameters EU and B1/2, with increasing H concentration is explained by the release of strain in the network and associated decrease in structural disorder. All of these correlations in a-BxC:Hy are found to be very similar to those

  9. Complementary incorporation of boron compounds with different cellular targets in melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Morre, D.E. [University of Sydney, Dept. of Pharmacy, Sydney, NSW (Australia); Setiawan, Y.; Allen, B.J. [St George Cancer Care Centre, Kogarah, NSW (Australia)


    Full text. The heterogeneity of malignant tumours is well known, and post-surgical control may only be achieved by the application of a number of adjuvant therapies. In boron neutron capture therapy (BNCT), a similar effect could be achieved by utilising boron compounds with quite different uptake and incorporation mechanisms. While tumour growth delay or control can be induced by BNCT in animal models, long term control in human patients may be much more difficult. Thus we have carried out experiments with two boron compounds which exhibit quite different pharmacokinetics and interact with cancer cells by quite different mechanisms. The compounds studied were p-boronophenylalanine (BPA) and boronated low density lipoprotein (B-LDL). Non-specific boron compounds such as n-alkyl carboranes can be delivered to melanoma tumour cells when incorporated in reconstituted LDL. Biodistribution studies were performed with BALB/c mice bearing subcutaneous Harding-Passey melanoma xenografts. The mice were pretreated with a high fat diet and hydrocortisone to down regulate the non-autonomous LDL receptors. A tumour to blood boron concentration ratio of 5:1 was achieved 18 hours after administration of B-LDL. The same compound administered in a non-specific arachis oil vehicle failed to demonstrate selective uptake in the tumour. Neutron capture therapy using B-LDL as the boron delivery vehicle produced a growth delay effect on the tumours which was equivalent to that found when BPA was administered as the fructose complex to develop a similar boron concentration in the tumour. This is indicative that the boron microdistribution across different types of tumour cells achieved by B-LDL has a similar effect to that achieved by BPA in the tumour model, even though the uptake mechanisms for BPA and B-LDL are different. BPA uptake is thought to be dependent on the amino acid transport mechanism, whereas receptor density determines LDL incorporation. Thus the combined administration

  10. Synthesis, structural characterization, and reactivity studies of 5-CF3SO3-B10H13. (United States)

    Berkeley, Emily R; Ewing, William C; Carroll, Patrick J; Sneddon, Larry G


    In contrast to previous reactions carried out in cyclopentane solvent at room temperature that produced 6-TfO-B10H13 (TfO = CF3SO3), the reaction of closo-B10H10(2-) with a large excess of trifluoromethanesulfonic acid in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf) gave exclusively the previously unknown 5-TfO-B10H13 isomer. Experimental and computational studies demonstrated that the difference in the products of the two reactions is a result of 6-TfO-B10H13 isomerizing to 5-TfO-B10H13 above room temperature in bmimOTf solutions. Reactivity studies showed that 5-TfO-B10H13: (1) is deprotonated by reaction with 1,8-bis(dimethylamino)naphthalene to form the 5-TfO-B10H12(1-) anion; (2) reacts with alcohols to produce 6-RO-B10H13 boryl ethers (R = Me and 4-CH3O-C6H4); (3) undergoes olefin-hydroboration reactions to form 5-TfO-6,9-R2-B10H11 derivatives; and (4) forms a 5-TfO-6,9-(Me2S)2-B10H11 adduct at its Lewis acidic 6,9-borons upon reaction with dimethylsulfide. The 5-TfO-6,9-(Me2S)2-B10H11 adduct was also found to undergo alkyne-insertion reactions to form a range of previously unreported triflate-substituted 4-TfO-ortho-carboranes (1-R-4-TfO-1,2-C2B10H10) and reactions with triethylamine or ammonia to form the first TfO-substituted decaborate [R3NH(+)]2[2-TfO-B10H9(2-)], and [R3NH(+)]2[1-TfO-B10H9(2-)] (R = H, Et) salts.

  11. Thermal and hydrothermal stability of selected polymers in a nuclear reactor environment (United States)

    Kim, Jinho

    The focus of this study is the development and understanding of polymer based burnable poison rod assemblies (BPRAs) in pressurized water reactors (PWRs). This material substitution reduces the water displacement penalty at the end of cycle (EOC) currently found with the B4C/Al 2O3 BPRAs that displace moderator water in PWRs. This gives rise to a longer fuel cycle due to the extra moderation from hydrogen in polymer structures. Finding synthetic polymers that endure a severe nuclear reactor circumstance is a challenge. Aside from the proper thermal stability at the range of 350--600°C in the core for a single cycle, the hydrothermal stability at near-critical water condition (350°C, 20.7MPa) is required to maintain the safe and controlled nuclear reaction because a danger comes if water might possibly penetrate inside the burnable poison rod by the failure of zircaloy cladding. There are two approaches to obtain a boron source (burnable position material) in hydrogen containing polymers. One is to utilize the boron source directly by synthesizing boron-containing polymers. A second approach is to find commercial polymers that have an appropriate thermal, hydrothermal, radiational stability and high hydrogen content; and then add an inorganic boron source such as B4C to form a composite material. Poly (diacetylene-siloxane-carborane)s and other silicon based precursor polymers were introduced to observe their thermal and hydrothermal stability. However, we found that the degradation of Si-O-Si, which was presented in the polymer, was an unfavorable disadvantage under near-critical water (350°C, 20.7MPa) even though they formed dense network structures. In addition, the Si-O bond is quite sensitive to variety of reagents, including base and acid. Therefore, the degradation rate might be accelerated by high H+ and OH- ion concentrations at the near-critical water condition. For the second approach, a number of candidate matrix polymers were screened for new

  12. The influence of hydrogen on the chemical, mechanical, optical/electronic, and electrical transport properties of amorphous hydrogenated boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Nordell, Bradley J.; Karki, Sudarshan; Nguyen, Thuong D.; Rulis, Paul; Caruso, A. N.; Paquette, Michelle M., E-mail: [Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States); Purohit, Sudhaunshu S. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States); Li, Han; King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States); Dutta, Dhanadeep; Gidley, David [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lanford, William A. [Department of Physics, University at Albany, Albany, New York 12222 (United States)


    Because of its high electrical resistivity, low dielectric constant (κ), high thermal neutron capture cross section, and robust chemical, thermal, and mechanical properties, amorphous hydrogenated boron carbide (a-B{sub x}C:H{sub y}) has garnered interest as a material for low-κ dielectric and solid-state neutron detection applications. Herein, we investigate the relationships between chemical structure (atomic concentration B, C, H, and O), physical/mechanical properties (density, porosity, hardness, and Young's modulus), electronic structure [band gap, Urbach energy (E{sub U}), and Tauc parameter (B{sup 1/2})], optical/dielectric properties (frequency-dependent dielectric constant), and electrical transport properties (resistivity and leakage current) through the analysis of a large series of a-B{sub x}C:H{sub y} thin films grown by plasma-enhanced chemical vapor deposition from ortho-carborane. The resulting films exhibit a wide range of properties including H concentration from 10% to 45%, density from 0.9 to 2.3 g/cm{sup 3}, Young's modulus from 10 to 340 GPa, band gap from 1.7 to 3.8 eV, Urbach energy from 0.1 to 0.7 eV, dielectric constant from 3.1 to 7.6, and electrical resistivity from 10{sup 10} to 10{sup 15} Ω cm. Hydrogen concentration is found to correlate directly with thin-film density, and both are used to map and explain the other material properties. Hardness and Young's modulus exhibit a direct power law relationship with density above ∼1.3 g/cm{sup 3} (or below ∼35% H), below which they plateau, providing evidence for a rigidity percolation threshold. An increase in band gap and decrease in dielectric constant with increasing H concentration are explained by a decrease in network connectivity as well as mass/electron density. An increase in disorder, as measured by the parameters E{sub U} and B{sup 1/2}, with increasing H concentration is explained by the release of strain in the network and associated decrease in

  13. Excitations, optical absorption spectra, and optical excitonic gaps of heterofullerenes: I. C60, C59N+ and C48N12

    Energy Technology Data Exchange (ETDEWEB)

    Xie, R; Bryant, G W; Sun, G; C.Nicklaus, M; Heringer, D; Frauenheim, T; Manaa, M R; Smith, Jr., V H; Araki, Y; Ito, O


    Low-energy excitations and optical absorption spectrum of C{sub 60} are computed by using time-dependent (TD) Hartree-Fock (HF), TD-density functional theory (TD-DFT), TD-DFT-based tight-binding (TD-DFT-TB) and a semiempirical ZINDO method. A detailed comparison of experiment and theory for the excitation energies, optical gap and absorption spectrum of C{sub 60} is presented. It is found that electron correlations and collective effects of exciton pairs play important roles in assigning accurately the spectral features of C{sub 60} and the TD-DFT method with non-hybrid functionals or a local spin density approximation leads to more accurate excitation energies than with hybrid functionals. The level of agreement between theory and experiment for C{sub 60} justifies similar calculations of the excitations and optical absorption spectrum of a monomeric azafullerene cation C{sub 59}N{sup +} exhibits distinguishing spectral features different from C{sub 60}: (1) the first singlet is dipole-allowed and the optical gap is redshifted by 1.44 eV; (2) several weaker absorption maxima occur in the visible region; (3) the transient triplet-triplet absorption at 1.60 eV (775 nm) is much broader and the decay of the triplet state is much faster. The calculated spectra of C{sub 59}N{sup +} characterize and explain well our measured ultraviolet-visible (UV-vis) and transient absorption spectra of the carborane anion salt [C{sub 59}N][Ag(CB{sub 11}H{sub 6}Cl{sub 6}){sub 2}]. For the most stable isomer of C{sub 48}N{sub 12}, we predict that the first singlet is dipole-allowed, the optical gap is redshifted by 1.22 eV relative to that of C{sub 60}, and optical absorption maxima occur at 585, 528, 443, 363, 340, 314 and 303 nm. We point out that the characterization of the UV-vis and transient absorption spectra of C{sub 48}N{sub 12} isomers is helpful in distinguishing the isomer structures required for applications in molecular electronics. For C{sub 59}N{sup +} and C{sub 48}N

  14. Novel inorganic heterocycles from dimetalated carboranylamidinates. (United States)

    Harmgarth, Nicole; Gräsing, Daniel; Dröse, Peter; Hrib, Cristian G; Jones, Peter G; Lorenz, Volker; Hilfert, Liane; Busse, Sabine; Edelmann, Frank T


    Mono- and dianionic carboranylamidinates are readily available in one-pot reactions directly from o-carborane (1). In situ-monolithiation of 1 followed by treatment with N,N'-diisopropylcarbodiimide, (i)PrN=C=N(i)Pr, or N,N'-dicyclohexylcarbodiimide, CyN=C=NCy, provided the lithium carboranylamidinates (o-C2B10H10C(NH(i)Pr)(=N(i)Pr)-κ(2)C,N)Li(DME) (2a) and (o-C2B10H10C(NH(i)Cy)(=N(i)Cy)-κ(2)C,N)Li(THF)2 (2b). Controlled hydrolysis of 2a,b afforded the free carboranylamidines o-C2B10H11C(NH(i)R)(=N(i)R) (3a: R = (i)Pr, 3b: R = Cy). The first dimetalated carboranylamidinates, o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(DME)2 (4a) (DME = 1,2-dimethoxyethane) and o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(THF)4 (4b), were prepared in high yield (83% yield) directly from 1 using a simple one-pot synthetic protocol. Treatment of 4b with 2 equiv. of Me3SiCl afforded the disilylated derivative o-C2B10H10-κ(2)C,N-[C(N(i)PrSiMe3)(=N(i)Pr)]SiMe3 (5). Dianionic 4b also served as an excellent precursor for novel inorganic heterocycles incorporating the closo-1,2-C2B10H10 cage, including the unsymmetrical distannene [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]Sn=Sn[((i)PrN)2C(n)Bu]2 (6) and the azaphosphole derivative [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]PPh (7). Surprisingly, it was found that the synthesis of new inorganic ring systems from dianionic carboranylamidinates can also be achieved by employing only 1 equiv. of n-butyllithium in the generation of the anionic carboranylamidinate intermediates. Using this straightforward one-pot synthetic protocol, the Group 14 metallacycles [o-C2B10H10C(NCy)(=NCy)-κ(2)C,N]SiR2 (R = Cl (8), Me (9), Ph (10)) and [o-C2B10H10C(NCy)([=NCy)-κ(2)C,N]GeCl2 (11) have become accessible. The same synthetic strategy could be successfully adapted to prepare the corresponding Group 4 metallocene derivatives Cp2Ti[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (12) and Cp2Zr[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (13). The molecular structures of 2b, 3b, 4b, 5, 6, 7, 10, 12, and 13 were

  15. Interaction of host-guest complexes of cucurbit[n]urils with double probe guests

    Institute of Scientific and Technical Information of China (English)

    MA; Peihua; DONG; Jun; XIANG; Shuangchun; XUE; Saifeng; ZH


    [1]Freeman, W. A., Mock, W. L., Shih, N. Y., Cucurbituril, J. Am.Chem. Soc., 1981, 103: 7367-7368.[2]Day, A. I., Arnold, A. P., Method for synthesis cucurbiturils, WO 0068232, 2000, 8.[3]Kim, J., Jung, I. S., Kim, S. Y. et al., New cucurbituril homologues: syntheses, isolation, characterization, and X-ray crystal structures of cucurbit[n]uril (n = 5, 7 and 8), J. Am. Chem. Soc.,2000, 122(3): 540-541.[4]Day, A. I., Blanck, R. J, Amold, A. P., A cucurbituril-based gyroscane: a new supramolecular form, Angew. Chem. Int. Ed., 2002,41(2): 275-277.[5]Blanck, R. J., Sleeman, A. J. White, T. J. et al., Cucurbit[7]uril and o-carborane self-assemble to form a molecular ball bearing,Nano. Lett., 2002, 2(2), 147-149.[6]Liu, J. X., Tao, Z., Xue, S. F. et al., Investigation of host-guest compounds of cucurbit[n = 5-8]uril with some piperazine derivatives, Chin. J. Inorg. Chem., 2004, 20(2): 139-147[7]Zhou, Y. L., Liu, Y., Inclusion complex of β-cyclodextrin and α-aminopyridine and its assembling behavior, Science in China,Ser. B, 2004, 34(1): 68-74.[8]Ong, W., Kaifer, A. E., Molecular encapsulation by cucurbit[7]uril of the apical 4,4'-bipyridinium residuein newkome-type dendrime,Angew. Chem. Inter. Ed., 2003, 42: 2164-2167.[9]Samsonenko, D. G., Gerasko, O. A., Mitkina, T. V. et al., Synthesis and crystal structure of supramolecular adducts of macrocyclic cavitand cucurbituril with chromium (Ⅲ) and nickel (Ⅱ) aqua complexes, Russian J. Coord. Chem. (Translation of Koordinatsionnaya Khimiya), 2003, 29(3): 166-174.[10]He, X. Y., Li, G., Chen, H. L., A new cucurbituril-based metallo-rotaxane, Inorg. Chem. Commun., 2002, (5): 633-641.[11]Fedin, V. P., Sokolov, M. N., Dybtsev, D. N. et al., Supramolecular assemblies of [Mo3Se4Clx(H2O)9-x](4-x)+ with cucurbituril;complementarity control through the variation of x, Inorg. Chim.Acta., 2002, 331(1): 31-38.[12]Lorenzo, S., Day, A., Craig, D. et al., The first endoannular metal halide