Preparation of Aromatic Fluorides Via Diazotization and Photochemically Induced Fluoro-Dediazoniation of Aromatic Amines in Anhydrous Hydrogen Fluoride - Organic Base Solutions

Fluoro-dediazoniation of aromatic diazonium ions, produced by the diazotization of the corresponding aromatic amines with NaNO₂ in anhydrous hydrogen fluorides (AHF) - organic base solutions, was accelerated photochemically to afford Ar-F efficiently in AHF - organic base solutions in situ.     

HPLC Determination of Chlorpropamide in Human Serum by Fluorogenic Derivatization Based on the Suzuki Coupling Reaction with Phenylboronic Acid

A fluorogenic derivatization method for the determination of chlorpropamide in human serum was developed by means of high-performance liquid chromatography (HPLC) with fluorescence detection. The Suzuki coupling reaction with a non-fluorescent reagent, phenylboronic acid (PBA), was employed to convert chlorpropamide into highly fluorescent biphenyl derivative. Chlorpropamide was extracted from human serum by liquid–liquid extraction with toluene after addition of hydrochloric acid, and subsequently reacted with PBA. Because the fluorogenic derivatization was highly selective for aryl halide, the proposed method allowed sensitive and selective detection of chlorpropamide with a detection limit (at a signal to noise ratio of 3) of 0.5 ng mL⁻¹. The sensitivity of our method was from 4 to 100 times better than HPLC–UV, gas chromatography, and LC-mass spectrometry.

     

HPLC Determination of Chlorpropamide in Human Serum by Fluorogenic Derivatization Based on the Suzuki Coupling Reaction with Phenylboronic Acid

A fluorogenic derivatization method for the determination of chlorpropamide in human serum was developed by means of high-performance liquid chromatography (HPLC) with fluorescence detection. The Suzuki coupling reaction with a non-fluorescent reagent, phenylboronic acid (PBA), was employed to convert chlorpropamide into highly fluorescent biphenyl derivative. Chlorpropamide was extracted from human serum by liquid–liquid extraction with toluene after addition of hydrochloric acid, and subsequently reacted with PBA. Because the fluorogenic derivatization was highly selective for aryl halide, the proposed method allowed sensitive and selective detection of chlorpropamide with a detection limit (at a signal to noise ratio of 3) of 0.5 ng mL^?1. The sensitivity of our method was from 4 to 100 times better than HPLC–UV, gas chromatography, and LC-mass spectrometry.     

Stereoselective Synthesis of Angularly Methylated Trans Fused Hydrindanone by Conjugate Reduction

The reducing reagent consisting of methylcopper, diiso-butylaluminum hydride and hexamethylphosphoric triamide causes the stereoselective trans conjugate reduction of the hydrindenone 1 to produce predominantly the angularly methylated trans fused hydrindanone 3.     

Enantioselective Synthesis of δ-Lactones with Lipase-Catalyzed Resolution and Mitsunobu Reaction

Both enantiomers of a series of δ-lactones (e.g., δ-decalactone, δ-dodelactone, and δ-hexadecalactone) were synthesized stereoselectively by Novozym 435–catalyzed resolution. Furthermore, only (S)-enantiomers of δ-lactones were synthesized with a combination of Novozym 435–catalyzed resolution and Mitsunobu reaction.     

Selenium-Containing π-Conjugated Compounds for Electronic Molecular Materials

Abstract

Novel selenium-containing π-conjugated compounds have been studied for the development of organic metals, superconductors, and field-effect-transistors. Methylenedithiotetraselenafulvalene (MDT-TSF) and its related electron donors are effectively synthesized by the recently developed synthetic method consisting of the one-pot formation of 1,3-diselenole-2-selones, the deprotection/realkylation procedure of the protected tetrachalcogenafulvalene-thiolate and -selenolate, and the ring closing reaction via trans-alkylation on sulfur or selenium atom. These new compounds serve as good electron donors for developing not only highly conducting charge-transfer salts (> 10 ³ S cm^?1) but also superconducting salts. Among six selenium-containing methylenedichalcogeno-tetrachalcogenafulvalenes, we found that four of them can produce superconducting salts, indicating that the present compounds are superior class of electron donors.

For the development of high-performance organic semiconductors for organic field effect transistor (OFET) devices, we focused our attention to selenophene-containing acene-type compounds, namely benzo[1,2-b:4,5-b′]diselenophene (BDS) derivatives hitherto unknown. A new synthetic method for BDS derivatives consisting of double heterocycle-formation on the central benzene ring has been established and has made it possible to synthesize a range of BDS derivatives. Among them, 2,6-diphenyl derivative (DPh-BDS) shows very high hole mobility of 0.17 cm ² /Vs, which is classified into the highest class of field-effect mobility of organic thin films.     

1,2,4‐Triazol‐3‐ylidenes with an N‐2,4‐Dinitrophenyl Substituent as Strongly π‐Accepting N‐Heterocyclic Carbenes

The synthesis and characterisation of a series of new Rh and Au complexes bearing 1,2,4‐triazol‐3‐ylidenes with a N‐2,4‐dinitrophenyl (N‐DNP) substituent are described. IR, NMR, single‐crystal X‐ray diffraction and computational analyses of the Rh complexes revealed that the N‐heterocyclic carbenes (NHCs) behaved as strong π acceptors and weak σ donors. In particular, a natural bond orbital (NBO) analysis revealed that the contributions of the Rh→C_carbene π backbonding interaction energies (ΔE_bb) to the bond dissociation energies (BDE) of the Rh? C_carbene bond for [RhCl(NHC)(cod)] (cod=1,5‐cyclooctadiene) reached up to 63 %. The Au complex exhibited superior catalytic activity in the intermolecular hydroalkoxylation of cyclohexene with 2‐methoxyethanol. The NBO analysis suggested that the high catalytic activity of the Au^I complex resulted from the enhanced π acidity of the Au atom.     

Trace level determination of polycyclic aromatic hydrocarbons in river water with automated pretreatment HPLC

A novel on‐line pretreatment pump‐injection HPLC system for polycyclic aromatic hydrocarbons is proposed. We report novel pump‐injection HPLC‐based on‐line SPE with a specially designed pretreatment column for the determination of trace amounts of chemical substances in surface water. Polycyclic aromatic hydrocarbons are well known for strong carcinogenicity and thus a severe concentration control is required for drinking water and/or river water, which is the main resource of tap water. We found it possible to detect ng/L levels of polycyclic aromatic hydrocarbons by using pump‐injection column switching HPLC with fluorescence detection. To avoid the phenomenon, in which polycyclic aromatic hydrocarbons can be often adsorbed on the surface of flow lines of HPLC by their highly hydrophobicity especially resin‐made parts in sample delivery pump, we employed “autodilution” device that provides reliable recovery and repeatability. Additionally, real water samples were collected and then the spiked polycyclic aromatic hydrocarbons were determined at ng/L levels.     

A Fluorescent Probe for Rapid,High‐Contrast Visualization of Folate‐Receptor‐Expressing Tumors In Vivo

Folate receptors (FRs) are membrane proteins involved in folic acid uptake, and the alpha isoform (FR‐α) is overexpressed in ovarian and endometrial cancer cells. For fluorescence imaging of FRs in vivo, the near‐infrared (NIR) region (650–900 nm), in which tissue penetration is high and autofluorescence is low, is optimal, but existing NIR fluorescent probes targeting FR‐α show high non‐specific tissue adsorption, and require prolonged washout to visualize tumors. We have designed and synthesized a new NIR fluorescent probe, FolateSiR‐1 , utilizing a Si‐rhodamine fluorophore having a carboxy group at the benzene moiety, coupled to a folate ligand moiety through a negatively charged tripeptide linker. This probe exhibits very low background fluorescence and afforded a tumor‐to‐background ratio (TBR) of up to 83 in FR‐expressing tumor‐bearing mice within 30 min. Thus, FolateSiR‐1 has the potential to contribute to the research in the field of biology and the clinical medicine.     

Analysis of Nitrification in Agricultural Soil and Improvement of Nitrogen Circulation with Autotrophic Ammonia-Oxidizing Bacteria

Accumulations of inorganic nitrogen (NH₄ ⁺, NO₂ ^?, and NO₃ ^?) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄ ⁺ was observed, and the reaction of NH₄ ⁺?→?NO₂ ^? appeared to be slower than that of NO₂ ^??→?NO₃ ^? in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0?×?10³–1.0?×?10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032–0.26 % of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0?×?10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.