K-doping effect of the superconductivity in K2xFeTe1-xSx (0.07≤x≤0.3)

Bulk samples of K doping K_2xFeTe_1-xS_x with x = 0.07, 0.1, 0.2, 0.3 are successfully prepared by using easy-to-use stable compound K₂S as the reactant. The lattice constant calculated from X-ray diffraction patterns indicate that K ions enter the Fe-Te-S layers. K doping is beneficial enhance the superconductivity transition temperature from the R-T curves. The apparent diamagnetic signal is observed in M-T curves when the content of K is smaller than 0.1. However, differential curves (dM/dT) in K-rich samples appear sharp slope mutations, which means that the Meissner effect signal is covered by the increased excess ferromagnetic ions. The number of excess Fe magnetic ions is proportional to K content, which may play an important role in determining the superconductivity.     

Alkyl-chain branched effect on the aggregation and photophysical behavior of polydiarylfluorenes toward stable deep-blue electroluminescence and efficient amplified spontaneous emission

The control of the condensed superstructure of light-emitting conjugated polymers(LCPs) is a crucial factor to obtain high performance and stable organic optoelectronic devices.Side-chain engineering strategy is an effective platform to tune inter chain aggregation and photophysical behaviour of LCPs.Herein,we systematically investigated the alkyl-chain branched effecton the conformational transition and photophysical behaviour of polydiarylfluorenes toward efficient blue optoelectronic devices.The branched side chain will improve materials solubility to inhibit interchain aggregation in solution according to DLS and optical analysis,which is useful to obtain high quality film.Therefore,our branched PEODPF,POYDPF pristine film present high luminance efficiency of 36.1% and 39.6%,enhanced about 20%relative to that of PODPF.Compared to the liner-type sides' chain,these branched chains also suppress chain planarization and improve film morphological stability effectively.Interestingly,the branched polymer also had excellent stable amplified spontaneous emission(ASE) behaviour with low threshold(4.72 μJ/cm~2) and a center peak of 465 nm,even thermal annealing at 220 C in the air atmosphere.Therefore,side-chain branched strategy for LCPs is an effective means to control interchain aggregation,film morphology and photophysical property of LCPs.     

Stimuli-responsive fluorescent supramolecular polymer network based on a monofunctionalized leaning tower[6]arene

A fluorescent supramolecular polymer network with an excellent triple-stimuli responsive property based on metal–ligand coordination and host–guest interactions has been constructed from a terpyridine-monofunctionalized leaning tower[6]arene, a tetraphenylethylene AIEgen, and a bridging coordination ion (Zn²⁺). Addition of competitive binding agents, trifluoroacetic acid, and/or pillar[5]arene can break the metal coordination and/or host-guest inclusion complexation, and thermal heating can weaken the non-covalent interactions in the supramolecular polymer gel, all leading to the gel-to-sol transition.     

Superabsorbent Capability and High Retention Ability of China Clay (Kaolinite)/Polyacrylic Acid Composites for Aqueous Solution

Majority of superabsorbent polymers (SAPs) yet reported either have low gel strength or high production cost. Therefore, we synthesized a novel polyacrylic acid-grafted China clay (Kaolinite) super-absorbent polymer composite (SAPC) with high thermal stability, low cost of production and superior sorption and retention capability for water and salt solution. The resulting SAPCs were extensively characterized and analysed by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results suggested that the composites were thermally stable. Water absorbency increased with increase of clay content up to 45%, while further increase in clay content decreased the water absorbency. Percentage of acrylic acid (AA) and clay by weight shows the optimum absorbency in 35% and 40% respectively. Crosslinker and initiator contents were optimized to be 0.5% and 0.3% by weight respectively. The resulting polymer composite showed high water absorbency of about 785 g/g and 103 g/g of 1% NaCl solution with above 90% retention ability at 50 oC.     

Iodine-mediated one-pot synthesis of C-3 acylated indolizines from pyridines,aryl methyl ketones and acrylate derivatives

An I₂/CuI-promoted multi-component reaction from pyridines, aryl methyl ketones and electron deficient acrylates has been accomplished in a “one-pot” manner, which provides a straightforward and efficient access to C-3 acylated indolizines. The key intermediate of N-ylides is hypothesized to be generated in situ from pyridines and (hetero)aryl methyl ketones in the presence of iodine. This method has been applied in the synthesis of two molecules with anticonvulsant and anti-inflammatory activities.     

DDQ-promoted direct C–H amination of ethers with N-alkoxyamides under visible-light irradiation and metal-free conditions

A C(sp³)–N bond forming reaction between N-alkoxyamides and simple ethers has been developed. In the presence of commercially available 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), a variety of N-methoxyamides and ethers undergo this transformation smoothly to deliver the corresponding products in good yields under visible-light irradiation and metal-free conditions at room temperature.     

Asymmetric transfer hydrogenations of β-N-substituted enamino esters with ammonia borane

Optically active β-amino acids and their derivatives are very useful building blocks in synthetic and medicinal chemistry. The catalytic asymmetric reduction of β-enamino esters is one of the most efficient approaches for their synthesis. Ammonia borane with low molecular weight, high hydrogen capacity, and good stability, is an ideal hydrogen source for the transfer hydrogenation. However, only a few successful examples have been reported for the asymmetric reduction with ammonia borane. In this work, an asymmetric metal-free transfer hydrogenation of β-N-substituted enamino esters with ammoinia borane was successfully realized by using a frustrated Lewis pair of Piers’ borane and (S)-tert-butylsulfinamide as a chiral catalyst. A variety of β-amino acid derivatives were obtained in 51–90% yields with up to 91% ee.     

Dicitrinones E and F,citrinin dimers from the marine derived fungus Penicillium citrinum HDN-152-088

Two new citrinin dimers named dicitrinones E and F (1 and 2), together with one biogenetically related known citrinin monomer (3), were isolated from the marine derived fungus Penicillium citrinum HDN-152-088. All structures including the absolute configurations were elucidated on the basis of comprehensive spectroscopic data, and assisted by ECD calculations. Among them, compounds 1 and 2 belong to the class of citrinin dimers with a rare carbon-bridged C-7/C-7′ linkage. Compound 1 displayed antioxidant activity with IC₅₀ value of 23.73 μM.     

Halogenation of 1,1-diarylethylenes by N-halosuccinimides

An efficient method for the preparation of 2,2-diarylvinyl halides from the corresponding 1,1-diarylethylenes has been developed. N-Halosuccinimides (N-bromosuccinimide or N-chlorosuccinimide) were used as the halogenation reagents. The practicability of this method is highlighted by its simple operation, broad substrate scope and capability for large-scale reaction.     

山东产大颗粒高温高压合成钻石的多种谱学方法研究

山东济南中乌新材料有限公司利用六面顶油压机生产出大颗粒钻石,为了掌握这些合成钻石的品质及与天然钻石的区分方法,采用宽频诱导发光光谱仪（GV5000）、红外光谱仪、钻石特征光谱检测仪（PL5000）、激光诱导击穿光谱仪和X射线能谱仪,对该公司生产的225粒无色、蓝色和黄色高温高压（HPHT）合成钻石进行检测,并与天然钻石对比。HPHT合成钻石样品的晶形以（111）晶面和（100）晶面共存的聚形为主导。原石切磨成圆钻形成品的出成率在20%~67%之间,净度级别为VVS-P,颜色级别为D-H。通过GV5000分析,三种颜色样品均可观察到立方八面体生长结构发光图案,无色HPHT合成钻石为强蓝色荧光和磷光,发光峰位于495 nm,与晶格中的顺磁氮有关;蓝色HPHT合成钻石为蓝-绿蓝色荧光和蓝色磷光,发光峰位于501 nm,与晶格中的顺磁氮、硼有关;黄色HPHT合成钻石为弱绿色荧光和磷光,显示556和883 nm Ni+相关发光峰,这些特征可与天然钻石相区分。红外光谱分析表明,无色HPHT合成钻石在1 332~1 100 cm-1无明显氮相关吸收,在2 802 cm-1有B0相关吸收,为含有少量硼的Ⅱa型;蓝色HPHT合成钻石位于1 294 cm-1有与B-相关的强吸收,归属为Ⅱb型;黄色HPHT合成钻石位于1 130和1 344 cm-1有与孤氮相关的明显吸收,归属为Ⅰb型。PL5000光致发光光谱显示,三种颜色HPHT合成钻石可检测到659,694,707,714和883 nm等镍相关缺陷发光峰。相比之下,无色和黄色天然钻石通常为Ⅰa型,具有1 282和1 175 cm-1等聚合氮的红外光谱吸收,光致发光光谱通常可检测到415 nm（N₃）零声子线,由孤氮、硼和镍等缺陷导致的光谱特征极为罕见。因此,红外光谱和光致发光光谱特征可作为重要的鉴别依据。激光诱导击穿光谱仪检测到无色HPHT合成钻石的出露包裹体主要成分为Fe。X射线能谱分析显示,对于含包裹体较多的样品,无色和蓝色HPHT合成钻石可检测到Fe,黄色HPHT合成钻石可检测到Fe和Ni,为其中包裹体的成分,这可作为HPHT合成钻石鉴定性特征。综上所述,通过GV5000超短波紫外荧光和磷光测试,配合红外光谱和光致发光光谱特征,结合包裹体成分特征,可以有效区分该研究的合成钻石和天然钻石。