Substitution of the laser borane anti-BH with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron hydrides.

Reaction of anti-BH1 with pyridine in neutral solvents gives sparingly soluble BH-3',8'-Py3a as the major product (ca. 53%) and BH-6',9'-Py2 (ca. 15%) as the minor product, with small quantities of BH-8'-Py 4 (ca.

Duplex-selective ruthenium-based DNA intercalators.

We report the design and synthesis of small molecules that exhibit enhanced luminescence in the presence of duplex rather than single-stranded DNA. The local environment presented by a well-known [Ru(dipyrido[3,2-a:2',3'-c]phenazine)L2 ](2+) -based DNA intercalator was modified by functionalizing the bipyridine ligands with esters and carboxylic acids. By systematically varying the number and charge of the pendant groups, it was determined that decreasing the electrostatic interaction between the intercalator and the anionic DNA backbone reduced single-strand interactions and translated to better duplex specificity.

The contrarotational fluxionality of [3,3-(PMe2Ph)2-closo-3,1,2-PtC2B9H11] and related species.

DFT calculations allied with experimental crystallographic and NMR results elucidate the energetics and the geometrical and (11)B nuclear shielding changes in the contrarotational fluxionality of [3,3-(PMe2Ph)2-closo-3,1,2-PtC2B9H11] and confirm the identities of two stable rotational conformers. There is a relatively unhindered contrarotation of the {Pt(PR3)2} and nido-shaped carbons-together {C2B9H11} entities about an axis that contains the platinum atom, with a transition from trihapto to tetrahapto to pentahapto metal-to-cluster interaction as the rotation progresses from 0° to 90°, and a reversal as it progresses in turn through to 180°, and thence through a similar cycle through to 360° for a complete rotation. The overall energy minimum is the trihapto conformation, but there is also an island of stability for the tetrahapto conformation at slightly higher energy, corresponding to experimental observation of these two configurations.

Stabilization of a highly porous metal-organic framework utilizing a carborane-based linker.

The first tritopic carborane-based linker, H3BCA (C15B24O6H30), based on closo-1,10-C2B8H10, has been synthesized and incorporated into a metal-organic framework (MOF), NU-700 (Cu3(BCA)2). In contrast to the analogous MOF-143, NU-700 can be activated with retention of porosity, yielding a BET surface area of 1870 m(2) g(-1).

Zwitterionic weak-link approach complexes based on anionic icosahedral monocarbaboranes.

The anionic hemilabile phosphinothioether ligand, [1-(Ph2PCH2CH2S)-closo-1-CB11H11 ](-), which is functionalized with an anionic icosahedral monocarbaborane anion, was synthesized in three steps from [HNMe3][closo-CB11H12]. The ligand was used to synthesize a family of zwitterionic Weak-Link Approach (WLA) complexes that contain platinum(II), palladium(II), and rhodium(I). These complexes were characterized using multinuclear NMR spectroscopy, high-resolution mass spectrometry, and single-crystal X-ray diffraction analyses.

An exceptionally high boron content supramolecular cuboctahedron.

A boron-rich supramolecular cuboctahedron containing an impressive 240 boron atoms has been synthesized via coordination-driven assembly. The cuboctahedron, which is composed of Cu(2+) paddle-wheel nodes and carborane-isophthalic acids, was obtained simply and in high purity. The ability to precisely characterize the nanostructure via X-ray diffraction makes it unique among boron-rich nanostructures.

General strategy for the synthesis of rigid weak-link approach platinum(II) complexes: tweezers, triple-layer complexes, and macrocycles.

Air-stable, heteroligated platinum(II) weak-link approach (WLA) tweezer and triple-layer complexes that possess P,X-Aryl hemilabile ligands (P^ = Ph2PCH2CH2-, X = chalcoethers or amines) have been synthesized via the halide-induced ligand rearrangement (HILR) reaction, using a one-pot, partial chloride-abstraction method. The approach is general and works with a variety of phosphine-based hemilabile ligands; when a P,S-Ph ligand is used as the relatively strongly chelating ligand, heteroligated complexes are formed cleanly when an ether- (P,O-Ph), amine- (P,N-Ph2), or fluorinated thioether-based (P,S-C6F4H) hemilabile ligand is used as the weakly chelating counterpart. The HILR reaction has also been used to synthesize bisplatinum(II) macrocycles free of oligomeric material without having to resort to the high-dilution conditions typical for macrocycle synthesis.

Crystal-packing trends for a series of 6,9,12,15,18-pentaaryl-1-hydro[60]fullerenes.

The relationship between the size of the substituents of aryl groups in a series of fifteen 6,9,12,15,18-pentaaryl-1-hydro[60]fullerenes and the solid-state structures and packing motifs of these compounds has been analyzed. Pentaarylfullerenes have a characteristic "badminton shuttlecock" shape that causes several derivatives to crystallize into columnar stacks. However, many pentaarylfullerenes form non-stacked structures with, for example, dimeric, layered, diamondoid, or feather-in-cavity relationships between molecules.

Unfairly forgotten member of the iodocarborane family: synthesis and structural characterization of 8-iodo-1,2-dicarba-closo-dodecaborane, its precursors, and derivatives.

8-Iodo-1,2-dicarba-closo-dodecaborane (7) was prepared in three steps starting from decaborane-14 with 20% overall yield. In the presence of nucleophiles, compound 7 undergoes selective removal of the boron vertex in the position para to the iodine substituent to form the anionic nido-carborane 1-iodo-7,8-dicarba-nido-undecaborate. Capping of the corresponding dicarbollide dianion with BI(3) led to formation of the new carborane, 3,10-diiodo-1,2-dicarba-closo-dodecaborane (15).

A coordination chemistry dichotomy for icosahedral carborane-based ligands.

Although the majority of ligands in modern chemistry take advantage of carbon-based substituent effects to tune the sterics and electronics of coordinating moieties, we describe here how icosahedral carboranes-boron-rich clusters-can influence metal-ligand interactions. Using a series of phosphine-thioether chelating ligands featuring meta- or ortho-carboranes grafted on the sulfur atom, we were able to tune the lability of the platinum-sulfur interaction of platinum(II)-thioether complexes. Experimental observations, supported by computational work, show that icosahedral carboranes can act either as strong electron-withdrawing ligands or electron-donating moieties (similar to aryl- or alkyl-based groups, respectively), depending on which atom of the carborane cage is attached to the thioether moiety.

Complexes of gold(I), silver(I), and copper(I) with pentaaryl[60]fullerides.

Gold(I), silver(I), and copper(I) phosphine complexes of 6,9,12,15,18-pentaaryl[60]fullerides 1a and 1b, namely, [(4-MeC(6)H(4))(5)C(60)]Au(PPh(3)) (2a), [(4-t-BuC(6)H(4))(5)C(60)]Au(PPh(3)) (2b), [(4-MeC(6)H(4))(5)C(60)]Ag(PCy(3)) (3a), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PPh(3)) (3b), [(4-t-BuC(6)H(4))(5)C(60)]Ag(PCy(3)) (3c), [(4-MeC(6)H(4))(5)C(60)]Cu(PPh(3)) (4a), and [(4-t-BuC(6)H(4))(5)C(60)]Cu(PPh(3)) (4b), have been synthesized and characterized spectroscopically. All complexes except for 3c were also characterized by single-crystal X-ray diffraction. Several coordination modes between the cyclopentadienyl ring embedded in the fullerene and the metal centers are observed, ranging from η(1) with a slight distortion toward η(3) in the case of gold(I), to η(2)/η(3) for silver(I), and η(5) for copper(I).

Stabilization of acyclic phosphazides using the ortho-closo-dicarbadodecaboranyl residue.

The reactions of triphenylphosphine with the azido-ortho-closo-dicarbadodecaboranes 1-N(3)-2-R-closo-1,2-C(2)B(10)H(10) [R = Me (1a), Ph (1b)] produce the stable and isolatable carboranyl phosphazides 1-(N(3)PPh(3))-2-R-closo-1,2-C(2)B(10)H(10) [R = Me (2a), Ph (2b)] in good yields. Single crystal X-ray diffraction analysis revealed that, in the solid state, phosphazide 2a adopts an unusual s-cis conformation, whereas 2b adopts an s-trans conformation.

Gold(I) triphenylphosphine complexes incorporating pentaarylfulleride ligands.

Two gold(I) complexes, (Ph(3)P)Au[C(60)(4-MeC(6)H(4))(5)] (1) and (Ph(3)P)Au[C(60)(4-t-BuC(6)H(4))(5)] (2), were prepared in excellent yield and characterized by single-crystal X-ray diffraction. Complex 1, grown from two solvent systems, has different coordination modes of the fullerene-embedded Cp ring to the (PPh(3))Au fragment. For 1.

Toward unidirectional rotary motion in nickelacarboranes: characterization of diastereomeric nickel bis(dicarbollide) complexes derived from the [nido-7-CH3-7,8-C2B9H11]- anion.

Two diastereomeric pairs of nickel bis(C-monomethyldicarbollide) complexes, derived from the racemic [nido-7-CH(3)-7,8-C(2)B(9)H(11)](-) anion, have been synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Neutral (dd/ll) [1(2),1'(2')-Me(2)-closo-3,1,2-Ni(IV)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(IV)C(2)B(9)H(10)] 1 and (meso) [1,2'-Me(2)-closo-3,1,2-Ni(IV)C(2)B(9)H(10)-{3:3'}-closo-3',1',2'-Ni(IV)C(2)B(9)H(10)] 2 adopt typical cisoid conformations in the solid state. The temperature-dependent (11)B and (1)H NMR spectra of 2 indicate that the energy barrier to the interconversion of racemic rotational isomers is 66.

Self-assembling fullerenes for improved bulk-heterojunction photovoltaic devices.

The fullerene adducts 1a and 1b, whose molecular shapes either promote or hinder the formation of 1-D stacks, have been examined for their potential to form 1-D wire-like domains in bulk-heterojunction organic solar cells. The photovoltaic efficiency of solar cells based on blends of the stacking fullerene 1a with regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) is greatly enhanced compared to nonstacking model fullerene 1b.

Frail older patient care by interdisciplinary teams: a primer for generalists.

Frail older patients-unlike younger persons in the health care system or even well elders-require complex care. Most frail older patients have multiple chronic illnesses. Optimum care cannot be achieved by following the paradigm of ongoing traditional health care, which emphasizes disease and cure.