Icosahedral carboranes as scaffolds for congested regioselective polyaryl compounds: the distinct distance tuning of C-C and its antipodal B-B.

Four-fold aryl substituted o-carborane derivatives with defined patterns of substitution at the antipodal region of the cluster carbon atoms have been achieved. It is proven that this region is congested but lacks steric hindrance. Also, the two antipodal sites C-C and B9-B12 are affected very distinctly by electron donor substituents.

Synthesis of globular precursors.

o-Carborane (C2 B10 H12 ) was adapted to perform as the core of globular macromolecules, dendrons or dendrimers. To meet this objective, precisely defined substitution patterns of terminal olefin groups on the carborane framework were subjected to Heck cross-coupling reactions or hydroboration leading to hydroxyl terminated arms. These led to new terminal groups (chloro, bromo, and tosyl leaving groups, organic acid, and azide) that permitted ester production, click chemistry, and oxonium ring opening to be performed as examples of reactions that demonstrate the wide possibilities of the globular icosahedral carboranes to produce new dendritic or dendrimer-like structures.

Synthesis of Periphery-Decorated and Core-Initiated Borane Polyanionic Macromolecules.

A new class of globular polybranched macromolecules that contain multiple anionic metallacarborane clusters at the o-carborane periphery is reported. The water soluble high boron rich containing molecules could be of interest for boron neutron capture therapy (BNCT) as well as for drug delivery. The reinforced electrostatic noncovalent interactions between anionic polyethylene glycol cobaltabisdicarbollide (PEG-COSAN) branches and the ammonium cation have been shown using ESI-MS.

Stepwise sequential redox potential modulation possible on a single platform.

Step by step: The cluster [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) is an excellent platform for making a stepwise tunable redox potential system by dehydroiodination. With the addition of up to eight iodine substituents (purple; see picture), there is a fall in the E(1/2)(Co(III)/Co(II)) value from -1.80 V to -0.

A highly radiopaque vertebroplasty cement using tetraiodinated o-carborane additive.

Bone cements for vertebroplasty must have a much better radiocontrast level than cements for knee or hip arthroplasty. This is generally accomplished by adding a relatively large portion of BaSO(4), although this affects the physical-mechanical and biological properties of the cement. This prompted us to develop an alternative radiopaque cement, on the basis of unique highly radiopaque methacrylic microspheres.

Additive tuning of redox potential in metallacarboranes by sequential halogen substitution.

The first artificially made set of electron acceptors is presented that are derived from a unique platform Cs[3,3'-Co(C(2)B(9)H(11))(2)], for which the redox potential of each differs from its predecessor by a fixed amount. The sequence of electron acceptors is made by substituting one, two, or more hydrogen atoms by chlorine atoms, yielding Cs[3,3'-Co(C(2)B(9)H(11-y)Cl(y))(C(2)B(9)H(11-z)Cl(z))]. The higher the number of chlorine substituents, the more prone the platform is to be reduced.