芳基硒代酰胺与α-卤代乙酸在醇中的硒转移反应——二烷氧羰基甲基二硒醚的简便合成

芳基硒代酰胺与氯乙酸在各种醇中无催化剂下以1∶1和1∶2的比例投入, 发生硒转移反应, 不同原料投入比下的反应生成了同一种C—Se—Se—C偶联产物——具有多功能团的二烷氧羰基甲基二硒醚, 提供了一种新的合成二烷氧羰基甲基二硒醚的简便方法, 且反应具有条件温和、产率高、原料易得和选择性好等优点. 为了研究该反应机理, 选择α-溴代乙酸甲酯或α-溴代乙酸乙酯在无催化剂、中性条件下, 乙醇溶液中与苯基硒代酰胺室温下反应, 投料比为1∶1和2∶1, 结果也都生成了同一类产物二甲氧羰基甲基二硒醚或二乙氧羰基甲基二硒醚, 同时还分离得到了相应的副产物苯甲酸乙酯. 对该C—Se—Se—C偶联反应发生的可能机理作了推测.     

氢氧化铯催化下,二芳基二硒醚对端炔的加成:高选择性合成(Z)-1,2-二芳硒基烯

氢氧化铯催化下,以商业THF作溶剂,端炔与二芳基二硒醚在氮气保护下,25或35℃时反应,立体选择地生成(Z)-1,2-二芳硒基烯.     

一种新型二硒卟啉的合成及其与牛血清白蛋白的相互作用

以5-(4-羟基苯基)-10,15,20-三苯基卟啉和硒粉为原料,合成了新型二硒双卟啉,用紫外可见光谱（UV-Vis）,红外光谱（IR）,核磁共振氢谱（1H NMR）,高分辩质谱（HR-MS）对目标产物的结构进行了确认。同时,考察了新化合物与牛血清白蛋白(BSA)相互作用的荧光光谱,由实验数据求得该二硒双卟啉与BSA的结合常数Ksv＝3.35×104 L/mol。分析荧光结果表明二硒双卟啉与BSA之间发生了较强的静态猝灭。     

Indium-mediated cleavage of diphenyl diselenide and diphenyl disulfide: efficient one-pot synthesis of unsymmetrical diorganyl selenides, sulfides, and selenoesters

A convenient and efficient method was developed for the synthesis of alkyl phenyl selenides, sulfides, and selenoesters in one-pot reaction by using indium metal. The reaction showed the selectivity for tert-alkyl, benzylic, and allylic halides over primary and secondary alkyl halides. For the reaction of primary and secondary alkyl iodides and bromides, the yields of selenides were improved by the addition of a catalytic amount of iodine.     

A highly regioselective bisselenation of allenes with diphenyl diselenide catalyzed by tetrakis(triphenylphosphine)palladium(0)

Tetrakis(triphenylphosphine)palladium(0) acts as an effective catalyst for highly regioselective bisselenation of allenes with diphenyl diselenide.     

Effect of electrical contact on performance of WSe2 field effect transistors

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) such as tungsten diselenide (WSe₂) have spead many interesting physical properties, which may become ideal candidates to develop new generation electronic and optoelectronic devices. In order to reveal essential features of 2D TMDCs, it is necessary to fabricate high-quality devices with reliable electrical contact. We systematically analyze the effect of graphene and metal contacts on performance of multi-layered WSe₂ field effect transistors (FETs). The temperature-dependent transport characteristics of both devices are tested. Only graphene-contacted WSe₂ FETs are observed with the metal-insulator transition phenomenon which mainly attributes to the ultra-clean contact interface and lowered contact barrier. Further characterization on contact barrier demonstrates that graphene contact enables lower contact barrier with WSe₂ than metal contact, since the Fermi level of graphene can be modulated by the gate bias to match the Fermi level of the channel material. We also analyze the carrier mobility of both devices under different temperatures, revealing that graphene contact can reduce the charge scattering of the device caused by ionized impurities and phonon vibrations in low and room temperature regions, respectively. This work is expected to provide reference for fabricating 2D material devices with decent performances.     

Experimental and theoretical 31P and 77Se nuclear magnetic shielding tensors for bis(dineopentoxyphosphorothioyl) diselenide

An intergrown crystal of two phases of bis(dineopentoxyphosphorothioyl) diselenide 1 was investigated by goniometer ³¹P NMR. From the angular dependence of the chemical shift, the tensors of a triclinic and a monoclinic phase were determined. The principal values σ₁₁, σ₂₂, and σ₃₃ of the absolute nuclear magnetic shielding tensors for the triclinic phase are 134.1, 227.2, and 375.5 ppm and for the monoclinic phase are 132.4, 227.8, and 374.2 ppm, respectively. In both cases, the principal axis 3 of the ³¹P tensor is directed nearly along the P=S bond and the principal axis 2 is nearly perpendicular to the S=P—Se plane. Calculations of the ³¹P and ⁷⁷Se nuclear magnetic shielding tensors were performed for molecules of both phases of 1 and for model compounds by the sum-over-states density functional perturbation theory IGLO method. The rms distances between calculated and experimental ³¹P NMR icosahedral tensor values σ_j(j = 1,…,6) amount to 17–21 ppm. The calculated and experimental orientations of the ³¹P principal axes show a maximum difference of 5° and rms distances of 3.2 and 3.3°. For the principal value σ₃₃ of the selenium shielding tensor the agreement between calculated and experimental values is satisfactory, but the calculated values σ₁₁ and σ₂₂ are distinctly too small. Calculations for a model compound in which the methyl groups of the neopentoxy residue are substituted by protons lead practically to the same results.     

Synthesis of Allyl Selenides Promoted by an Sm/ZnCl2 Bimetal System in the Presence of Water

The reaction of diselenides with allylic bromides proceeded smoothly in an Sm/ZnCl₂ bimetal system in THF‐H₂O to afford allyl selenides in good yield.     

Synthesis of selenium bridged metallacycles via oxidative addition of diaryl diselenide across Re-Re bond: Novel one-pot reaction approach

One-pot synthesis of novel M₂E₂L₂ type metallacycles [L(CO)₃Re(μ-SeR)₂Re(CO)₃L] (1-5) was accomplished by oxidative addition of diaryl diselenide to low-valent transition metal carbonyl with monodentate pyridine ligands. In metallacycles 1-5, where L = pyridine ligand, R = C₆H₅, CH₂C₆H₅, the pyridyl groups bonded to metal centres invariably adopted cis conformation due to π-π interaction whereas, in compounds 1a and 2a, the pyridyl ligands were oriented in trans conformation. When bulky phenyl groups are introduced at para position of pyridyl rings, as in case of metallacycle 3, the steric hindrance disrupts the soft interaction and resulted into the expansion of space in between two phenylpyridyl groups and created a void. The Metallacycles 1-5 have been characterised by elemental analysis, NMR, IR, absorption and emission spectroscopic techniques. Molecular structures of 1, 1a, 2, 2a, 3 and 4 were determined by single crystal X-ray diffraction analysis and the structural studies of 1, 2, 3 and 4 revealed that the pyridyl groups attached to the metal centres exhibited cis conformation, while 1a, 2a displayed trans conformation.