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We suggest a new phenomenological potential for heavy quarkonium. The potential has a Lorentz vector term motivated by experimental leptonic widths for vector mesons and perturbative QCD at short distances and a Lorentz scalar term responsible for quark confinement at large distances. Using this potential we calculate the energy levels, leptonic decay widths, radiative transition rates and hadronic decay rates of the \(c\bar c, b\bar b\) and \(t\bar t\) systems. Most results agree well with the experiment. 相似文献
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[60]Fullerene reacted with various beta-dicarbonyl compounds in the presence of Mn(OAc)3*2H2O to generate dihydrofuran-fused [60]fullerene derivatives or 1,4-bisadducts. Dihydrofuran-fused [60]fullerene derivatives 2 could be formed by treatment of alpha-unsubstituted beta-diketones 1a-e or beta-ketoesters 1f and 1g with [60]fullerene in refluxing chlorobenzene in the presence of Mn(III). Solvent-participated unsymmetrical 1,4-bisadducts 3 were obtained through the reaction of [60]fullerene with dimethyl malonate 1h or alpha-substituted beta-dicarbonyl compounds 1i-1n in toluene. A possible reaction mechanism for the formation of different fullerene derivatives is proposed. 相似文献
4.
Small molecule‐mediated glass transition of acrylic copolymers: Effect of hydrogen bonding strength on glass transition temperature
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Chongyang Liu Xiaotong Yin Yu Lin Aiguo Guan Guozhang Wu 《Journal of Polymer Science.Polymer Physics》2015,53(6):400-408
Poly(styrene‐co‐ethyl acrylate) [P(St‐co‐EA)] with different ratios of St/EA was mixed with the small molecule 4,4′‐thio‐bis(6‐tert‐butyl‐m‐methyl phenol) (AO300) to investigate the influence of hydrogen bonding strength on the glass transition behavior. The glass transition temperature (Tg) linearly increased after adding AO300, and the slope value decreased with increased St/EA ratio. All lines could be extended to 62 °C, demonstrating that Tg of the small molecule in situ detected by the polymer chain was much higher than that by small molecule itself (29 °C). Fourier transform infrared spectroscopy analysis showed that the small molecules began to be self‐associated at a concentration where the hydrogen bonded carbonyl ratio of the bulk polymer was approximately 0.5 and irrespective of the St/EA ratio. Above the critical loading, the mixture's Tg negatively deviated from the linearly extended lines because of self‐association of the small molecules. The apparent Tg of AO300 was found to strongly depend on intermolecular hydrogen bonding number and strength. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 400–408 相似文献
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An enantioselective carboxylative cyclization of propargylic alcohols and CO2 was realized under mild conditions,based on a kinetic resolution strategy,which enabled the synthesis of chiral cyclic carbonates and propargylic alcohols with promising yield and enantioselectivity simultaneously. 相似文献
7.
清洁催化氧化环己烯合成己二酸反应中酸性配体的作用 总被引:21,自引:0,他引:21
以30%H2O2为氧源,研究了Na2WO4·2H2O催化氧化环己烯制己二\r\n酸反应中的配体效应.在大多数情况下,配体的酸性越强,目标产物己\r\n二酸的产率越高.尽管一些酚类配体、L(+)抗坏血酸和8-羟基喹啉\r\n的酸性较弱,但己二酸的产率仍然很高.这表明影响目标产物产率的因\r\n素除配体的酸效应以外,还存在配体的配位效应.邻苯二酚和对苯二酚\r\n等酚类配体的实验结果表明,反应可能是通过络合催化反应机理完成的\r\n.对酸性配体用量及对反应动力学考察结果表明,反应过程中环氧化物\r\n水解为1,2-环己二醇是整个反应的控制步骤,反应体系的酸性起到决\r\n定性的作用. 相似文献
8.
利用咔唑醛与二氨基马来腈合成了一种对Cu2+和ClO-的响应的荧光探针分子CMN。探针分子与Cu2+作用后,紫外吸收光谱在394 nm处的吸光度迅速下降,颜色由黄色褪至无色;荧光光谱在452 nm处的发射峰迅速增强,出现明显的蓝色荧光。探针与ClO-作用后,溶液发生褪色,并在375 nm和394 nm出现强荧光发射,发出淡蓝色荧光。CMN通过配位过程实现了对Cu2+的检测,其检测限为47μmol/L;CMN在ClO-催化下亚胺键水解得到咔唑醛,实现了对ClO-的检测,检测限3.06μmol/L。CMN可作为荧光检测试纸快速检测环境中的Cu2+和ClO-。 相似文献
9.
Zhao Yang Renhe Hu Xiaotong Li Xin Wang Ren Gu Shiqing Han 《Tetrahedron letters》2017,58(24):2366-2369
An efficient one-pot three-component reaction of 2-iodoanilines, benzyl chlorides and elemental sulfur to form 2-substituted benzothiazoles in satisfactory yields (up to 98%) has been described. The reaction tolerated a wide range of functional groups on the aromatic ring. And heterocycle methylene chlorides substrates were also found to be compatible. 相似文献
10.
Xiaotong Zhang Eranda Wanigasekara Zachary S. Breitbach Edra Dodbiba Daniel W. Armstrong 《Rapid communications in mass spectrometry : RCM》2010,24(8):1113-1123
In previous studies, new electrospray ionization mass spectrometry (ESI‐MS) approaches were developed for the highly sensitive detection of singly and doubly charged anions in positive mode ESI‐MS by using specially synthesized dicationic and tricationic ion‐pairing agents, respectively. By detecting the positively charged ion complex in the positive mode, limits of detection (LODs) for the anions can be lowered by several magnitudes. In this work, we used eighteen newly synthesized tetracationic ion‐pairing agents, constructed with different geometries, linkages and cation moieties, for the detection of eighteen triply charged anions of different structural motifs. The LODs for these anions were from ten to several thousand times lower in the positive selective ion monitoring (SIM) mode than in the negative mode. These tetracationic agents also were shown to be useful for the detection of ?1 and ?2 anions. In addition, the LODs for ?3 anions can be further lowered by monitoring the product fragments of the ion‐pairing complexes in the single reaction monitoring (SRM) mode. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献