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Phenylene-cored small dendrimers containing three tonine peripheral o-carborane clusters were synthesizedvia Cu(I)-catalyzedHuisgen-type azide alkyne cycloaddition reactions. The resulting dendrimershave been characterized by IR and NMR spectroscopy and MALDI-TOF massspectral analysis. The biological evaluation of branched dendrimer 16containing nine carborane cages has been carried out usinghuman liver cancer cells (SK-Hep1). Dendrimer 16wasaccumulated in the SK-Hep1 cancer cells in a concentration-dependentmanner. The highest boron accumulation up to 2540 ng of boron/5 ×105cells was observed at a 50 μM concentration of 16over a period of 20 h. The high accumulation of 16into the tumor cell lines indicates that such dendritic boron drugdelivery platforms could be possible for application in boron neutroncapture therapy in cancer treatment. [ABSTRACT FROM AUTHOR]

Robust three-dimensional structure, aromaticity, high chemical and thermal stability of polyhedral boron clusters make them promising candidates for use in materials science. Boron clusters have been used for the synthesis of luminescent materials, polymers, coordination polymers or metal–organic frameworks, dendrimers, liquid crystals, and nonlinear optical materials. Some of these clusters have been used as molecular building blocks in nanoscience. This review summarizes the applications of polyhedral boron clusters in materials science. [ABSTRACT FROM AUTHOR]

The ability of ortho-, meta- and para-carboranes to enhance the emission intensity has been compared. For this purpose a series of carborane-appended 1,3,5-triphenylbenzene (TB) and 1,3,5- tris(biphenyl-4-yl)benzene (TBB) containing three ortho-, meta- and para-carborane clusters directly attached to the conjugated cores have been synthesized employing Suzuki, Heck, and trimerization reactions. The incorporation of the icosahedral carboranes was associated with a red shift in the UV absorption spectrum of up to 13 nm as well as enhancements of the emission intensities of up to 154%. The presence of ortho-carboranes showed the maximum red shift in the UV spectrum whereas the maximum enhancement of the emission intensity was observed in the presence of meta-carborane clusters. The order of π-conjugation extension is found to be ortho > meta ~ para. A comparative thermal analysis indicated o-carborane-appended trimers to be the most thermally stable in the series. Proton NMR spectra of reported carborane-appended trimers indicated that ortho- and meta-carborane cages have benzenelike characteristics. [ABSTRACT FROM AUTHOR]

The unusual reactivity of carborane mono- and dialdehydes with pyrroles in the presence of acid catalysts leads to the formation of a new class of carboranyl mono- and dipyrro derivatives. [ABSTRACT FROM AUTHOR]

The advancements in the synthetic chemistry of carboranes and metallacarboranes have given rise to diversified uses in medicinal chemistry, resulting in many new medical applications. An overview of the medicinal chemistry of carboranes is presented emphasizing the use of nanoparticles, dendrimers, porphyrins and carbohydrates as boron carriers. A review with 80 references. [ABSTRACT FROM AUTHOR]

The role of carborane clusters in organometallic chemistry is diverse. A number of carborane cage systems such as C2B4, C2B9and C2B10clusters have been extensively used for the synthesis of numerous metallacarboranes of s, p, d and f-block elements. An introduction to the chemistry of metallacarboranes is provided with an emphasis on the recent advances on the metallacarboranes of f-block elements. [ABSTRACT FROM AUTHOR]

A series of C3-symmetric p-conjugated compounds containing three to six o-carborane clusters have been synthesized by employing palladium-catalyzed Suzuki coupling reactions and palladium-catalyzed acetylation reactions, followed by silicon tetrachloride mediated trimerization reactions. Carborane-containing extended trimers were found to emit blue light. Incorporation of o-carborane clusters into extended p-conjugated systems led to 22-70% enhancement of their relative fluorescence quantum yields. Decapitation of o-carborane clusters made these extended trimers water soluble, and their aqueous solutions were also found to be fluorescent, but with a reduced fluorescence intensity. The carborane-appended p-conjugated compounds are found to be extremely thermally stable, and for some of these compounds only 10% mass loss occurred at temperatures close to 500 °C. The DSC thermograms of smaller Ccage-appended trimers indicate the occurrence of solid-solid phase transitions. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical denitrification of ground water was studied with an objective to maximize nitrate transformation to nitrogen gas. Aluminum, graphite, iron and titanium were selected as electrode materials. While aluminum, iron and titanium electrodes showed 70–97% nitrate reduction, with graphite electrode the removal was only 8%. Nitrate was transformed to ammonia with iron and aluminum electrodes but with titanium electrodes nitrogen was apparently the major end product. Iron electrodes exhibited the maximum reducing condition (ORP=−463mV) and titanium showed the minimum (ORP=–206mV). Nitrate reduction with titanium electrodes was retarded in the presence of chloride ions possibly due to formation of hypochlorite ions. The first-order nitrate transformation rate constant with respect to time decreased with decrease in current density. However, when the rate constant was expressed with respect to charge passed (Coulomb/l) it was nearly same under different experimental conditions (current density and pH). The study indicates that the process might be suitable for denitrification of drinking water. [Copyright &y& Elsevier]

Large dendrimers, noted Gn-3n+2cage, containing 3n+2 o-carborane cluster cages MeC2B10H10 at their peripheries (n = number of generation noted Gn) have been synthesized by Huisgen-type azide alkyne Cu1·catalyzed dipolar "click" cycloaddition reactions (CuAAC) between an o-carborane monomeric cluster containing an ethynyl group and arenecentered azido-terminated dendrimers Gn-3n+2N3 of generations 0, 1, and 2. Attempts to synthesize higher-generation dendrimers of this family yielded insoluble materials. The carborane dendrimers Go-9cage, G1-27cage, and G2-81 cage have been characterized by 1H, 13C, 11B NMR, elemental analysis, matrix-assisted laser descoptionlionization time of flight (MALDI-TOF) mass spectroscopy, and size exclusion chromatography (SEC) showing low polydispersities, dynamic light scattering (DLS) showing hydrodynamic diameters of 5.7 nm for the G1-27cage and the 12.9 nm for the G2-81 cage. These dendrimers are extremely robust thermally, with 10% mass loss temperatures of 411 °C for the Go-9cage, 371 °C for fhe G1-27cage, and 392 °C for the G2-8lcage. They all showed a strong absorption in the UV region peaking at 258 nm, whereas emission spectra of low intensities were observed between 280 and 480 nm. [ABSTRACT FROM AUTHOR]