Pentafluorophenol: A Superior Reagent for Condensations in Heterocyclic Chemistry

The use of pentafluorophenol as a superior reagent for heterocyclic condensations, where other traditional condensing agents such as DCC and CDI failed, has been demonstrated.     

New classes of carborane-appended 5-thio-D-glucopyranose derivatives

A series of carborane-appended 5-thio-D-glucopyranose (5-TDGP) derivatives containing one to two 5-TDGP moieties were synthesized via click cycloaddition reaction as well as following the traditional methods. Among the carboranyl-5-TDGP derivatives, the decapitated nido-carboranyl derivative 18 was found to be highly water-soluble and therefore its preliminary biodistribution study was conducted. A comparative biological evaluation of 18 versus its carboranyl-D-glucopyranose analog 19 with human hepatocellular carcinoma cells (SK-Hep1) indicated 5-TDGP to be a better boron carrier than normal D-glucopyranose. The carboranyl-5-TDGP 18 showed a nearly two fold increase in cellular boron accumulation than carboranyl-D-glucopyranose analog 19 over a period of 2 h. The accumulation of both 18 and 19 was found to occur in a temperature dependent manner. The higher accumulation of 18 suggested excellent promise for it to be a candidate for further evaluation as a future BNCT agent.     

Nano and dendritic structured carboranes and metallacarboranes: From materials to cancer therapy

An account of the current research carried out in our laboratories is presented. Included is the incorporation of several group 14 elements into charge-compensated carboranes. These species present a bonding pattern not found in other main group carboranes. In addition to our continuing studies of the syntheses and structures of organometallic compounds, the use of these compounds as catalysts and catalyst precursors has been investigated. The isotopic exchange reactions between ¹⁰B enriched boron hydrides with naturally abundant boranes catalyzed by Ru(0) nanoparticles has been studied. The Ru(0) nanoparticles were obtained by the reduction of [CpRuCp^∗RuCp^∗]PF₆ (Cp^∗ = C₅Me₅) with hydrogen and stabilized by the ionic liquid trihexyltetradecylphosphonium dodecylbenzenesulfonate [THTdP][DBS]. This was found to be an excellent, long lived catalyst for the exchange reaction of B-10 enriched diborane and naturally abundant decaborane(14). Other approaches to the production and use of nano-metal catalysts have also been explored. The reduction of the iridium carborane, (PPh₃)₂IrH(7,8-C₂B₉H₁₁) with hydrogen in the presence of trihexyltetradecylphosphonium methylsulfonate, [THTdP][MS], produced an Ir(0) nanoparticles that catalyzed the phenylborolation as did our Ir(sal = N-R = salicylaldiminato; COD = cyclooctadiene complex. Progress in the use of single wall carbon nanotubes (SWCNT) as boron delivery agents was also discussed.     

CeO<Subscript>2</Subscript> nanoparticle-modified electrode as a novel electrochemical interface in the quantification of Zn<Superscript>2+ </Superscript>ions at trace level: application to real sample analysis

A simple strategy has been proposed to quantify Zn²⁺ ions using CeO₂ nanoparticle-modified glassy carbon electrode. The CeO₂ nanoparticles were prepared by sucrose-nitrate decomposition method, and it was characterized by X-ray diffraction (XRD), FT-IR, TEM, and surface area analyzer. The synthesized CeO₂ nanoparticles were used as modifier molecules as a thin film on glassy carbon electrode (GCE) in the trace level quantification of Zn²⁺ by using cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV) techniques. The fabricated sensor exhibited a good analytical response towards Zn²⁺ ions. The modified electrode showed a wide linearity in the concentration range 20–380 μg L^?1 with a limit of detection 0.36 μg L^?1. The proposed electrochemical sensor was successfully applied to trace level Zn²⁺ quantification from real sample matrices.     

The synthesis and structure of 1,2,3,4-tetrahydro-2,4,4-trimethyl-8-nitroimidazo[1,5-d] [1,2,4]triazin-1-one,C8H11N5O3: A heterocycle with a rare ring system

The title compound (IV) was isolated as a by-product during the course of purification of 4-nitroimidazol-5-(N-methyl)hydrazide (II) by silica gel flash chromatography, employing chloroform-acetone (4:1) as the eluting solvent. The crystals are monoclinic, space groupP2₁/c,a=7.425(1),b=13.615(2),c=10.359(2) Å,=97.66(1)°,d _caled=1.44 g cm^–3, (MoK)=1.06 mm^–1,T=298 K. The number of unique reflections=2401, reflections withI3 (I)=1773;R=0.051,R _w =0.061. The bond distances inIV are: N-N, 1.419(3); N-C(=0), 1.359(3); N(H)-C(CH₃), 1.457(3); N(C)-C(CH₃), 1.501(3); N=C, 1.316(3); C=C, 1.368(3), N-C(=N), 1.353(3); N-C(=C), 1.367(2) Å.