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991.
石墨烯条带的电子结构与性质:电场及长度效应 总被引:1,自引:0,他引:1
在密度泛函理论(DFT)和含时密度泛函理论(TDDFT)的基础上对宽度上含有8个zigzag链的石墨烯条带(8-ZGNR)的基态和激发态的性质进行了理论研究,着重考察了条带长度及电场的影响.B3LYP杂化泛函的计算结果显示:在基态上,8-ZGNR的最低能量态并不具有磁性,随着长度的增加,才会显示出反铁磁的性质.静电场的加入使8-ZGNR显示出反铁磁性和半金属性.在激发态上,诱导电子会随着外激光脉冲的变化而发生移动和变化,但是相比而言,α自旋电子更容易被激发而产生较明显的诱导电子密度,而β自旋电子则更容易脱离外激光场的控制而产生非绝热现象. 相似文献
992.
Exceedingly Fast Copper(II)‐Promoted ortho CH Trifluoromethylation of Arenes using TMSCF3
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Ming Shang Shang‐Zheng Sun Dr. Hong‐Li Wang Dr. Brian N. Laforteza Prof. Dr. Hui‐Xiong Dai Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2014,53(39):10439-10442
The direct ortho‐trifluoromethylation of arenes, including heteroarenes, with TMSCF3 has been accomplished by a copper(II)‐promoted C? H activation reaction which completes within 30 minutes. Mechanistic investigations are consistent with the involvement of C? H activation, rather than a simple electrophilic aromatic substitution (SEAr), as the key step. 相似文献
993.
Trinuclear Gold Clusters Supported by Cyclic (alkyl)(amino)carbene Ligands: Mimics for Gold Heterogeneous Catalysts
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Dr. Liqun Jin David S. Weinberger Dr. Mohand Melaimi Dr. Curtis E. Moore Prof. Arnold L. Rheingold Prof. Guy Bertrand 《Angewandte Chemie (International ed. in English)》2014,53(34):9059-9063
The synthesis of air‐ and moisture‐stable trinuclear mixed‐valence gold(I)/gold(0) clusters is described. They promote the catalytic carbonylation of amines under relatively mild conditions. The synthetic route leading to the trinuclear clusters involves a simple ligand exchange from the readily available μ3‐oxo‐[(Ph3PAu)3O]+ complex. This synthetic method paves the way for the preparation of a variety of mixed‐valence gold(I)/gold(0) polynuclear clusters. Moreover, the well‐defined nature of the complexes demonstrates that the catalytic process involves a rare example of a definite change of oxidation state of gold from Au02AuI to AuI3. 相似文献
994.
Qi Wang Chenxi Zhang Dr. Bruce C. Noll Dr. Hai Long Dr. Yinghua Jin Prof. Dr. Wei Zhang 《Angewandte Chemie (International ed. in English)》2014,53(40):10663-10667
Shape‐persistent covalent organic polyhedrons (COPs) with ethynylene linkers are usually prepared through kinetically controlled cross‐coupling reactions. The high‐yielding synthesis of ethynylene‐linked rigid tetrameric cages via one‐step alkyne metathesis from readily accessible triyne precursors is presented. The tetrameric cage contains two macrocyclic panels and exhibits D2h symmetry. The assembly of such a COP is a thermodynamically controlled process, which involves the initial formation of macrocycles as key intermediates followed by the connection of two macrocycles with ethynylene linkages. With a large internal cavity, the cage exhibits a high binding selectivity toward C70 (K=3.9×103 L mol?1) over C60 (no noticeable binding). 相似文献
995.
Takahito Kasahara Young Jin Jang Léanne Racicot Dimitrios Panagopoulos Dr. Steven H. Liang Prof. Dr. Marco A. Ciufolini 《Angewandte Chemie (International ed. in English)》2014,53(36):9637-9639
A metathesis reaction occurs when a diaryliodonium triflate is heated with an aryl iodide, resulting in the formation of a new diaryliodonium triflate. 相似文献
996.
Molecularly Precise Dendrimer–Drug Conjugates with Tunable Drug Release for Cancer Therapy
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Dr. Zhuxian Zhou Dr. Xinpeng Ma Dr. Caitlin J. Murphy Dr. Erlei Jin Dr. Qihang Sun Prof. Youqing Shen Edward A. Van Kirk Prof. William J. Murdoch 《Angewandte Chemie (International ed. in English)》2014,53(41):10949-10955
The structural preciseness of dendrimers makes them perfect drug delivery carriers, particularly in the form of dendrimer–drug conjugates. Current dendrimer–drug conjugates are synthesized by anchoring drug and functional moieties onto the dendrimer peripheral surface. However, functional groups exhibiting the same reactivity make it impossible to precisely control the number and the position of the functional groups and drug molecules anchored to the dendrimer surface. This structural heterogeneity causes variable pharmacokinetics, preventing such conjugates to be translational. Furthermore, the highly hydrophobic drug molecules anchored on the dendrimer periphery can interact with blood components and alter the pharmacokinetic behavior. To address these problems, we herein report molecularly precise dendrimer–drug conjugates with drug moieties buried inside the dendrimers. Surprisingly, the drug release rates of these conjugates were tailorable by the dendrimer generation, surface chemistry, and acidity. 相似文献
997.
β‐Functionalization of Carboxylic Anhydrides with β‐Alkyl Substituents through Carbene Organocatalysis
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Zhichao Jin Shaojin Chen Yuhuang Wang Pengcheng Zheng Prof. Dr. Song Yang Prof. Dr. Yonggui Robin Chi 《Angewandte Chemie (International ed. in English)》2014,53(49):13506-13509
The first NHC‐catalyzed functionalization of carboxylic anhydrides is described. In this reaction, the β carbon behaves as a nucleophilic carbon and undergoes asymmetric reactions with electrophiles. Anhydrides with challenging β‐alkyl substituents work effectively. 相似文献
998.
Two Eu(III) ternary luminescent complexes, Eu(tpb-H)3(Tppo)2 and Eu(tpb-H)3(Topo)2 (Tppo: triphenylphosphine oxide, Topo: trioctylphosphine oxide, tpb: 4,4,4-trifluoro-1-phenyl-1,3-butanedione) were synthesized using β-diketonates and phosphine oxides as ligands. Luminescent polymers were fabricated by incorporating the deuterated Eu(III) complexes in a PMMA matrix. Luminescent PMMA containing Eu(tpb-D)3(Tppo)2 exhibited relatively higher quantum yield, faster radiation rate, sharper red emission and larger stimulated emission cross-section and the results indicated prepared luminescent polymers including Eu(tpb-D)3(Tppo)2 showed promising results for applications in novel organic Eu(III) devices. Additionally, the Eu(III) complexes and luminescent PMMA showed good thermostabilization. 相似文献
999.
提出了反相高效液相色谱法同时测定壮阳类保健品中4种PDE5抑制剂和达泊西汀含量的方法。样品溶于水中,再加甲醇提取。分取10μL提取液进样,并用Inertsil ODS-SP色谱柱为分离柱和由(A)三乙胺-乙酸-水(8+4+988)混合液,(B)乙腈和(C)0.02%(φ)磷酸溶液三者按不同比例相混的混合液作流动相进行梯度淋洗和分离。在检测波长290nm处进行测定。他达那非的质量浓度在1.25~25.0mg·L-1范围内与其峰面积呈线性关系,其余4种化合物的质量浓度在5.0~100mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.05~0.2mg·L-1之间。加标回收率在94.1%~109%之间,测定值的相对标准偏差(n=6)均小于1.0%。 相似文献
1000.