Complete transligation of (AcO)4Rh2 applied onto λ-Al2O3 with 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane

Complete transligation of (AcO)₄Rh₂ with 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane was conducted in the solid phase on λ-Al₂O₃. The reduction of Rh¹¹ to Rh^I on λ-Al₂O₃ at 130°C under the actionof the above-mentioned bicyclic phosphite is accompanied by the oxidation of the acetate anion to the acetoxyl radical. The oxidation products were detected by IR and ESR spectroscopy. 2,6-Di-tert-butyl-4-methylphenol was used as a “spin trap” to identify stable secondary radical cations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2036–2038, October, 1998.     

Mutual influence of metals and ligands in the complex formation of oxo anions of d-elements with chelating ligands

The complex-formation processes between ions of d-elements having multiple M=O bonds with bidentate monoanions, mainly 1,1-ditiolates, are considered. The data of ESR spectroscopy and X-ray diffration analysis for this type of complexes are analyzed. Owing to the strongtrans-effect of the M=O group, M-ligand valence bonds are not formed in thetrans-position to the M=O group, and only donor-acceptor M-ligand bonds are realized. The valence M-ligand bonds can arise only in the equatorial plane, incis-positions with thespect to the multiple M=O bond. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1471–1480, August, 1998.     

Hydrogen bonding in thiourea: diethyl oxalate complex in 2:1 ratio

The crystal structure of thiourea:diethyl oxalate in 2:1 ratio is the first of its kind where the diethyl oxalate exists as a solid which otherwise is a liquid at room temperature. It crystallizes in triclinic centrosymmetric space group P-1 with the following unit cell dimensions a = 7.1870(7) Å, b = 7.4890(8) Å, c = 8.3637(7) Å, α = 63.783(7)^∘, β = 67.41(1)^∘, γ = 64.933(7)^∘. The R-factor = 0.0386 for 1850 F_o > 4σ (F_o) and 0.0417 for all 2020 data. There is a center of inversion at the center of the C–C bond of diethyl oxalate. This system is stabilized by N–H ⋅s S and N–H ⋅s O hydrogen bonds.     

螺芴对含三齿磷配体的铱配合物光电性能的影响

合成了一种含4,5-二氮-9,9-螺二芴(sb)配体的三齿磷铱配合物Ir(tpit)(sb)Cl(tpitH2=亚磷酸三苯基酯),通过核磁共振氢谱和磷谱及高分辨质谱对其结构进行了确定。X射线单晶衍射分析表明,sb配体的存在扭曲了分子结构,有助于降低分子聚集及发光淬灭。与存在分子内π-π堆积的模型配合物Ir(tpit)(bpy)Cl(bpy=2,2′-联吡啶)对比进行了光电性能的研究。结果表明在聚甲基丙烯酸甲酯(质量分数1%)中配合物Ir(tpit)(sb)Cl的发光波长为512 nm,相对配合物Ir(tpit)(bpy)Cl的波长(520 nm)有了8 nm蓝移。配合物Ir(tpit)(sb)Cl的发光量子效率为30%,与配合物Ir(tpit)(bpy)Cl的94%相比有明显降低,说明了分子内π-π堆积作用在降低柔性基团非辐射跃迁率方面的重要作用。基于配合物Ir(tpit)(sb)Cl的有机电致发光器件,最大电流效率和外量子效率分别为14 cd·A-1和4.5%。而由于分子内π-π堆积作用,基于配合物Ir(tpit)(bpy)Cl器件的最大电流效率和外量子效率分别高达60 cd·A-1和18.2%。     

Synthesis of Thioglycosides in Room Temperature Ionic Liquid

An eco-friendly reaction for the preparation of thioglycosides has been developed using an ionic liquid as the solvent. Thioglycosides were obtained in excellent yields on treatment of per-O-acetylated sugar derivatives with thiols in the presence of boron trifluoride diethyl etherate in [Bmim][BF₄] as solvent at 20°C. Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the free supplemental file.     

Low-potential electrosynthesis of conducting and electroactive oligocatecholborane with blue light-emitting properties

Novel conducting oligocatecholborane (OCOB) with electrical conductivity of 3.73 × 10-2S cm-1 was successfully synthesized by low-potential electropolymerization of catecholborane (COB) in boron trifluoride diethyl etherate at 0.70 V versus Ag/AgCl. FT-IR and 1H-NMR spectra, together with the computational results, proved that COB was polymerized through the coupling at C(4) and C(5) positions and the reactive B―H bond was stable during the electrochemical polymerization. The resulting product was mainly composed of oligomers with short chain lengths by GPC and mass spectral results. The as-formed OCOB film showed good electrochemistry in monomer-free electrolytes with the electrochromic property from opaque blue to sap green. Fluorescence studies indicated that soluble OCOB can emit bright blue light under excitation of 365 nm UV light with the maximum emission at 396 nm and a fluorescence quantum yield of 0.21. The deposited OCOB also exhibited favorable thermal stability and smooth and compact morphology even at high magnifications.     

Polyazaphosphorus macrocycles

Abstract

A general way of preparation of phosphorus macrocycles is reported. Their chemical properties are described.     

A Flexible Route to Mannose 6-Phosphonate Functionalized Derivatives

A new approach for the synthesis of a mannose 6-phosphonate isosteric analog of mannose 6-phosphate is reported. The mannosylphosphonate has been prepared in a multistep synthesis involving an homologation reaction of the methyl f - D -mannopyranoside followed by an Arbuzov reaction between a bromohomomannosyl derivative and the tris (trimethylsilyl)phosphite. This approach, avoiding the deprotection of dialkylphosphonate, allowed us to prepare the mannose 6-phosphonate in good yield. The described method was successfully extended to the preparation of a mannose 6-phosphonate linked to a cholesteryl moiety. This strategy affords a more general route for a wide range of functionalized mannose 6-phosphonate derivatives.     

On-line solid phase extraction-liquid chromatography–mass spectrometry for trace determination of nerve agent degradation products in water samples

Three primary nerve agent degradation products (ethyl-, isopropyl- and pinacolyl methylphosphonic acid) have been determined in water samples using on-line solid phase extraction-liquid chromatography and mass spectrometry (SPE-LC–MS) with electrospray ionisation. Porous graphitic carbon was employed for analyte enrichment followed by hydrophilic interaction chromatography. Diethylphosphate was applied as internal standard for quantitative determination of the alkyl methylphosphonic acids (AMPAs). By treating the samples with strong cation-exhange columns on Ba, Ag and H form, the major inorganic anions in water were removed by precipitation prior to the SPE-LC–MS determination. The AMPAs could be determined in tap water with limits of detection of 0.01–0.07 μg L⁻¹ with the [M−H]⁻ ions extracted at an accuracy of ±5 mDa. The within and between assay precisions at analyte concentrations of 5 μg L⁻¹ were 2–3%, and 5–9% relative standard deviation, respectively. The developed method was employed for determination of the AMPAs in three natural waters and a simulated waste water sample, spiked at 5 μg L⁻¹. Recoveries of ethyl-, isopropyl- and pinacolyl methylphosphonic acid were 80–91%, 92–103% and 99–106%, respectively, proving the applicability of the technique for natural waters of various origins.