A series of mono-, di-, and triphosphoniumsubstituted triarylboranes, [Mes 2 BAr P ]I ([2]I), [MesBAr P 2 ]I 2 ([3]I 2 ), and [BAr P 3 ]I 3 ([4]I 3 ) (Ar P = 4-(MePh 2 P)-2,6-Me 2 -C 6 H 2 ), were prepared from the corresponding neutral boranes 2a−4a. The crystal structure of [4]I 3 determined by X-ray diffraction study reveals peripheral decoration of aryl groups with phosphonium moieties. The anion affinity of the cationic boranes for fluoride and cyanide ions was investigated by UV−vis absorption titrations in aqueous solution. The triarylboranes, [2]I−[4]I 3 bind both fluoride and cyanide ions in a DMSO/H 2 O (7:3 v/v) mixture with high binding constants (K). Comparison of the K values of triarylboranes for fluoride reveals that fluorophilicity increases with the increasing number of phosphonium moieties: [2] + (K = 2.3 × 10 1 M −1 ) < [3] 2+ (3.6 × 10 5 M −1 ) < [4] 3+ (1.0 × 10 7 M −1 ). A similar trend is also observed in the cyanide binding, with K values that are greater by 2−4 orders of magnitude than those in the fluoride binding. These results indicate an apparent additive effect of multiple phosphonium substitutions on the Lewis acidity enhancement of triarylboranes. The triphosphonium borane [4]Cl 3 , a water-soluble form of [4]I 3 , was further utilized in evaluating the anion affinity in water. While [4] 3+ is shown to hardly bind fluoride in buffered water at pH 7, it binds cyanide with a high binding constant (1.7 × 10 7 M −1 ).

An approach to the design of nido-carborane-based luminescent compounds that can exhibit thermally activated delayed fluorescence (TADF) is proposed. 7,8-Dicarba-nido-undecaboranes (nido-carboranes) having various 8-R groups (R=H, Me, i-Pr, Ph) are appended to the meta or para position of the phenyl ring of the dimesitylphenylborane (PhBMes ) acceptor, forming donor-acceptor compounds (nido-m1-m4 and nido-p1-p4). The bulky 8-R group and meta substitution of the nido-carborane are essential to attain a highly twisted arrangement between the donor and acceptor moieties, leading to a very small energy splitting between the singlet and triplet excited states (ΔE <0.05 eV for nido-m2, -m3, and -p3). These compounds exhibit efficient TADF with microsecond-range lifetimes. In particular, nido-m2 and -m3 display aggregation-induced emission (AIE) with TADF properties.

BackgroundDrug resistant tuberculosis (TB) is increasing in prevalence worldwide. Treatment failure and relapse is known to be high for patients with isoniazid resistant TB treated with standard first line regimens. However, risk factors for unfavourable outcomes and the optimal treatment regimen for isoniazid resistant TB are unknown. This cohort study was conducted when Vietnam used the eight month first line treatment regimen and examined risk factors for failure/relapse among patients with isoniazid resistant TB.MethodsBetween December 2008 and June 2011 2090 consecutive HIV-negative adults (≥18 years of age) with new smear positive pulmonary TB presenting at participating district TB units in Ho Chi Minh City were recruited. Participants with isoniazid resistant TB identified by Microscopic Observation Drug Susceptibility (MODS) had extended follow-up for 2 years with mycobacterial culture to test for relapse. MGIT drug susceptibility testing confirmed 239 participants with isoniazid resistant, rifampicin susceptible TB. Bacterial and demographic factors were analysed for association with treatment failure and relapse.ResultsUsing only routine programmatic sputum smear microscopy for assessment, (months 2, 5 and 8) 30/239 (12.6%) had an unfavourable outcome by WHO criteria. Thirty-nine patients were additionally detected with unfavourable outcomes during 2 year follow up, giving a total of 69/239 (28.9%) of isoniazid (INH) resistant cases with unfavourable outcome by 2 years of follow-up. Beijing lineage was the only factor significantly associated with unfavourable outcome among INH-resistant TB cases during 2 years of follow-up. (adjusted OR = 3.16 [1.54–6.47], P = 0.002).ConclusionOne third of isoniazid resistant TB cases suffered failure/relapse within 2 years under the old eight month regimen. Over half of these cases were not identified by standard WHO recommended treatment monitoring. Intensified research on early identification and optimal regimens for isoniazid resistant TB is needed. Infection with Beijing genotype of TB is a significant risk factor for bacterial persistence on treatment resulting in failure/relapse within 2 years. The underlying mechanism of increased tolerance for standard drug regimens in Beijing genotype strains remains unknown.

Nanowire-shaped silver have been synthesized by the polyol process in ethylene glycol as a reductant, polyvinylpyrrolidone (PVP) as a stabilizer, using a microwave technique. The products were characterized by transmission electron microscopy (TEM). The presence of sodium chloride in the polyol reduction of silver nitrate facilitated the production of silver nanowires. These wires were formed quickly (in approximately 3 minutes microwave heating). It was found that morphologies and sizes of silver nanostructures depended strongly on such experimental parameters as concentrations of PVP, NaCl, AgNO 3 , and heating time. The chloride ion was necessary to synthesize nanowire-shaped silver, and the sodium chloride likely controlled the rate of silver(I) reduction and initial seed formation.

Streaming potential is the result of coupling between a fluid flow and an electric current in porous rocks. The modified Helmholtz–Smoluchowski equation derived for capillary tubes is mostly used to determine the streaming potential coefficient of porous media. However, to the best of our knowledge, the fractal geometry theory is not yet applied to analyse the streaming potential in porous media. In this article, a fractal model for the streaming potential coefficient in porous media is developed based on the fractal theory of porous media and on the streaming potential in a capillary. The proposed model is expressed in terms of the zeta potential at the solid−liquid interface, the minimum and maximum pore/capillary radii, the fractal dimension, and the porosity of porous media. The model is also examined by using another capillary size distribution available in published articles. The results obtained from the model using two different capillary size distributions are in good agreement with each other. The model predictions are then compared with experimental data in the literature and those based on the modified Helmholtz–Smoluchowski equation. It is shown that the predictions from the proposed fractal model are in good agreement with experimental data. In addition, the proposed model is able to reproduce the same result as the Helmholtz–Smoluchowski equation, particularly for high fluid conductivity or large grain diameters. Other factors influencing the streaming potential coefficient in porous media are also analysed.

Heteroleptic tris-cyclometalated Ir(III) complexes bearing an o-carborane at the 4-or 5-position in the phenyl ring of the ppy ligand (closo-1 and -2) were prepared and characterized. The X-ray crystal structure of closo-1 reveals the fac arrangement of the three C ∧ N chelates around the Ir atom. Treatment of closo complexes with fluoride anions led to selective deboronation of the closo-carborane cage, producing the corresponding nido-carborane-substituted complexes (nido-1 and -2). Whereas closo-1 and -2 were almost nonemissive in THF, nido-1 and -2 were highly phosphorescent (Φ PL = 0.94−0.95). Theoretical studies suggested that, while the emission quenching in closo-1 can be ascribed to the substantial involvement of o-carborane in the 3 MLCT excited state, the intraligand charge transfer ( 3 ILCT) state from the nido-carborane to pyridyl moieties is responsible for the efficient phosphorescence in nido-1. The addition of fluoride to the buffered THF/H 2 O solution (1/1, v/v, pH 7) of closo-1 and -2 under mild heating led to strong emission intensity, allowing the turn-on phosphorescence detection of fluoride in aqueous medium at the ppb level.

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The novel iron(I) sandwich compound [Cp*Fe(η 4 -C 4 Py 4 )] (1) was prepared and characterized by various methods, including X-ray crystallography. Coordination-driven self-assembly of a diruthenium acceptor with the tetrapyridyl metalloligand [Cp*Fe(I)(η 4 -C 4 Py 4 )] led to a D 4 -symmetric three-dimensional M 4 L 2 tetragonal supramolecular cage. This cage was characterized by IR and high-resolution electrospray ionization mass spectrometry. Its solid-state structure was confirmed by X-ray crystallography, showing a novel D 4 cage system.