Effects of Different Eelectron-withdrawing Moieties on the General Photoelectric Properties of Fluorene-based Dimers

Here, 9,9,9'-tris(4-butoxyphenyl)-9H-9'H-2,2'-difluorene(DF) was synthesized as a reference for compa-rison, and diphenyl sulfone and triphenylphosphine oxygen were introduced to the 9-position of fluorene through a C-H coupling reaction to produce two fluorene-based oligomers 9',9'-[sulfonylbis(4,1-phenylene)]bis[9,9,9'-tris-(4-butoxyphenyl)-9H,9'H-2,2'-bifluorene](DF)₂SO₂ and phenylbis(4-{9,9',9'-tris(4-butoxyphenyl)-9H,9'H-[2,2'-bif-luorene]-9-yl}phenyl)phosphine oxide[(DF)₂PO]. Solid powders of all the three compounds exhibit excellent thermal stability with thermal temperature at 5% mass loss of 375, 429 and 383℃ for (DF)₂SO₂, (DF)₂PO and DF. In addition, owing to the distorted molecular structure and weak electron-absorbing ability of the acceptor, (DF)₂SO₂ and (DF)₂PO do not have obvious intramolecular charge transfer characteristics, and exhibit stable localized 394 nm/375 nm fluorescence emission peaks in different polar solvents. The absolute luminescence quantum efficiencies of (DF)₂SO₂, (DF)₂PO and DF solid powders are 20.83%, 10.03% and 59.46%. Compound DF has the highest quantum yield as an electron donor. The chromaticity coordinates of the blue OLED devices based on DF and DF₂SO₂ fabricated by solution spin coating were (0.19, 0.10) and (0.19, 0.11), which were closest to the deep blue region, and the corresponding maximum external quantum efficiencies are 1.45% and 0.87%, respectively, which are higher than that of (DF)₂PO(0.25%) and consistent with the difference in the solid-state quantum efficiency between them.     

Efficient microwave syntheses of the compounds Os3(CO)11L, L = NCMe, py, PPh3

The results of simple microwave-assisted ligand substitution reactions of Os₃(CO)₁₂ are reported. In a remarkably short period of time, the labile complex Os₃(CO)₁₁(NCMe) is prepared in high yield without the need for a decarbonylation reagent such as trimethylamine oxide. Microwave irradiation of Os₃(CO)₁₂ in a relatively small amount of acetonitrile is shown to be a useful first step in two-step, one-pot syntheses of the cluster complexes Os₃(CO)₁₁(py) and Os₃(CO)₁₁(PPh₃).     

An Efficient Synthesis of Stable Phosphorus Ylides Derived from Hydantoin and 5,5-dialkylhydantoins

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as hydantoin and 5,5-dialkylhydantoins. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphoranes Derived from Imides or Acetanilide Derivatives

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and strong NH-acids, such as acetanilide, 4-methylacetanilide, 2-cyanoacetanilide, 4-bromoacetanilide, 4-methoxyacetanilide, succinimide, malimide, or phthalimide. These stabilized phosphoranes exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

Study on the Development of Catalyst System for the Novel Rearrangement Reaction of Bicyclic Ketal Compound

A novel rearrangement of bicyclic ketals was investigated by using AcCl-NaI and MgBr₂-Ac₂O. Mono- and diacetylated products were isolated from these catalyst systems. Details of the chemistry are discussed.     

Structural,morphological, optical and sensing properties of SnSe and SnSe2 thin films as a gas sensing material

In this work, orthorhombic tin selenide thin films were grown onto three different substrates using an organophosphorus precursor (Ph₃PSe) via chemical vapor deposition. Structural, microstructural and morphological properties of the as-grown films were systematically investigated using XRD, ESEM and AFM respectively. Grain size, microstrain and dislocation were calculated and correlated with different factors. The effects of selenization temperature and substrate type on different film properties and gas sensing response of films deposited onto alumina substrates were investigated. XRD analysis reveals the appearance of a mixed phase as a function of temperature. Furthermore, substrate type plays a key role in the rate of appearance of each phase. EDAX analysis confirms the existence of the desired elements and detect the evaporation of selenium and the appearance of oxygen at higher temperatures. Atomic force microscopy (AFM) was used to investigate the surface topography of the grown thin films.Optical properties of the films grown onto glass and silicon substrates were studied. From the recorded optical data, a direct optical band gap in the range of 0.9–1.3 eV was obtained with an absorption coefficient α > 10⁴ cm⁻¹ throughout large spectral regions. Optical studies were remarkably affected by the obtained phase as well as the selenization temperature. Gas sensing properties of the samples deposited onto alumina substrates were examined as a new sensing material for detection of methane gas at different concentrations. SnSe sensors show high sensitivity, are reversible and exhibit fast response and recovery times compared to SnSe₂ sensors.     

正丁基黄原酸铜与三苯基膦配合物的结构和表征

合成并通过IR、UV、~1HNMR、TGA及单晶X射线衍射研究了正丁基黄原酸铜与三苯基膦配合物的结构和性能。该配合物属单斜晶系,空间群P2_1/c,晶胞参数为:a=11·000(2),b=20·090(4),c=17·320(4),β=103·800(3)°,V=3717·1(13)~3,Z=4。中心铜原子与来自正丁基黄原酸根的两个硫原子及三苯基膦的两个磷原子配位,呈扭曲的四面体构型。IR,UV及~1HNMR分析结果与晶体结构一致。热重分析研究表明该配合物从110℃开始分解,到295℃分解完全,留下CuS。     

Selective syntheses of benzoxazoles and N-(2-hydroxyaryl)pyrrolidin-2-ones from the corresponding cyclopropyl amides with PPh3/CX4

Benzoxazoles 2 can be smoothly synthesized by treatment of starting materials of N-(2-hydroxyaryl) cyclopropyl amides 1 with PPh₃/CCl₄ in acetonitrile in good yields. When PPh₃/CBr₄/MS 4 Å was used in the reaction system, the corresponding ring-expanding products 3 were obtained in moderate to good yields in acetonitrile at 80 °C. Using DCE as a solvent in this reaction, the corresponding 2-(3-chloropropyl)benzoxazoles 5 were obtained as major products.     

Preparation of thiocyanates and isothiocyanates from alcohols, thiols, trimethylsilyl-, and tetrahydropyranyl ethers using triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)/n-Bu4NSCN system

A combination of triphenylphosphine (PPh₃) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) provides a safe and easily available mixed reagent system for the conversion of 1° and 2° alcohols, thiols, trimethylsilyl-, and tetrahydropyranyl ethers to their corresponding thiocyanates and the 3° ones to isothiocyanates in good to high yields.     

Triphenylphosphine chalcogenides as efficient ligands for room temperature palladium(II)-catalyzed Suzuki-Miyaura reaction

A simple catalytic system based on PdCl₂ and triphenylphosphine chalcogenides (PPh₃X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine.