4,7-Bis[3-(dimesitylboryl)thien-2-yl]benzothiadiazole: Solvato-, Thermo-, and Mechanochromism Based on the Reversible Formation of an Intramolecular B-N Bond.

4,7-Bis-[3-(dimesitylboryl)thien-2-yl]benzothiadiazole (1) and monoborylated derivative 2 were synthesized and their chromic behavior was investigated. Photophysical measurements, single-crystal XRD analysis, and theoretical calculations revealed that an intramolecular B-N coordination bond formed reversibly. The equilibrium of this reversible bond formation depends on the solid-state structure, solvent, temperature, and mechanical forces, and leads to significant changes in the electronic structure and chromic behavior of these molecules. The responsiveness toward external stimuli, resulting in the reversible formation of open and closed forms of this system, is achieved through weak intramolecular B-N coordination bonds induced by the steric bulk of the mesityl groups on the boron centers.

A retinoic acid receptor agonist tamibarotene suppresses iron accumulation in the liver.

OBJECTIVE: Hepatic iron overload (HIO) and iron-induced oxidative stress have recently emerged as an important factor for the development and progression of insulin resistance. The aim of this study was to evaluate the effect of tamibarotene, a selective retinoic acid receptor α/ß agonist, on hepatic iron metabolism, based on our previous findings that retinoids suppress hepatic iron accumulation by increasing hepatic iron efflux through the regulation of hemojuvelin and ferroportin expression. DESIGN AND METHODS: We quantitated the non-heme iron content and iron metabolism-related gene expression in the liver, and serum lipid and blood glucose levels in KK-A(y) mice after dietary administration of tamibarotene. RESULTS: It was demonstrated that tamibarotene significantly reduced blood glucose and hepatic iron, but not serum lipids, and that hemojuvelin expression significantly decreased while ferroportin increased, as observed previously. CONCLUSIONS: These results suggest that tamibarotene is a promising alternative for the treatment of insulin resistance associated with HIO.

Modification of the σ-framework of [60]fullerene for bulk-heterojunction solar cells.

Modification of the σ-framework of [60]fullerene has been shown to be a new avenue toward n-type materials for bulk-heterojunction solar cells. This approach allowed distinct control of the LUMO level of the C(60)π-system and resulted in a clear improvement of an open-circuit voltage.

Triaryl(1-pyrenyl)bismuthonium salts: efficient photoinitiators for cationic polymerization of oxiranes and a vinyl ether.

Photoirradiation of triaryl(1-pyrenyl)bismuthonium salts in acetonitrile afforded triarylbismuthanes and pyrene, accompanied by the generation of protic acids. Triaryl(1-pyrenyl)bismuthonium hexafluoroantimonates have proven to behave as efficient photoinitiators for cationic polymerization of oxiranes and a vinyl ether, affording the corresponding polymers in good yields within 1 min.

The cbs mutant strain of Rhodococcus erythropolis KA2-5-1 expresses high levels of Dsz enzymes in the presence of sulfate.

Two mutants of the dibenzothiophene-desulfurizing Rhodococcus erythropolis KA2-5-1, strains MS51 and MS316, which express a high level of desulfurizing activity in the presence of sulfate, were isolated using the transposome technique. The level of dibenzothiophene-desulfurization by cell-free extracts prepared from mutants MS51 and MS316 grown on sulfate was about five-fold higher than that by cell-free extracts of the wild-type. This result was consistent with results of Western-blot analysis using antisera specific for DszA, DszB and DszC, the enzymes involved in the desulfurization of dibenzothiophene. Gene analysis of the mutants revealed that the same gene was disrupted in mutants MS51 and MS316 and that the transposon-inserted gene in these strains was the gene for cystathionine beta-synthase, cbs. The cbs mutants also expressed high levels of Dsz enzymes when methionine was used as the sole source of sulfur.

Enhancement and stabilization of desulfurization activity of Rhodococcus erythropolis KA2-5-1 by feeding ethanol and sulfur components.

We developed a fed-batch culture system fed with ethanol and restricted amounts of sulfur compounds to enhance and stabilize the desulfurizing activity in bacterial cells. In this system using dibenzothiophene (DBT) as the sole sulfur source, a desulfurizing bacterium Rhodococcus erythropolis KA2-5-1 cultivated with small amounts of sulfur showed stable desulfurizing activity and a low rate of growth. However, the cells cultured with excess amounts of sulfur showed unstable activity and a high growth rate. DBT had disadvantages as a sulfur source for cultivation because it is immiscible with water and toxic to cells. We then investigated water-soluble sulfur compounds for use as the sole sulfur source for the cultivation of R. erythropolis KA2-5-1 with desulfurizing activity, and found 2-aminoethanesulfonic acid to be the most effective. When 2-aminoethanesulfonic acid was used instead of DBT as the sole sulfur source in the fed-batch fermentation system, R. erythropolis KA2-5-1 showed the highest desulfurizing activity, 111 mmol of 2-HBP/kg-cells/h, a high growth rate (mu = 0.37/h) and a final cell concentration of 20.0 g-dry cells/l during 89 h of cultivation. The production levels of the desulfurizing enzymes in the bacterial cells cultivated with DBT or 2-aminoethanesulfonic acid were evaluated by immunoblot analysis with specific antisera, indicating that the same quantity of desulfurizing enzymes was expressed in both cases.