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991.
利用密度泛函理论研究了CH3CCl2F与F原子的反应机理.在MPW1K水平下计算了反应物、过渡态和产物的几何构型和频率,并进一步利用内禀反应坐标理论获得了反应的最小能量路径;在G3(MP2)水平下对所有驻点进行了单点能量校正.结果表明,CH3CCl2F与F原子的反应存在两个H迁移反应通道:CH2H′CCl 2F+F→C... 相似文献
992.
993.
994.
H. L. Cheng D. Y. Shi J. W. Zhao Z. D. Geng L. J. Chen P. T. Ma J. Y. Niu 《Russian Journal of Coordination Chemistry》2011,37(4):302-308
A novel 3D 3d–4f heterometallic polymer Pr4(H2O)9Cu3.5Cl0.5(Bpdc)6.5(OH)2 · 5H2O (I) (H2Bpdc = 2,2′-bipyridyl-5,5′-dicarboxylic acid) has been hydrothermally synthesized by the reaction of CuCl2 · 2H2O, PrCl3, H2Bpdc, TAA (TAA = 1H-tetrazolyl-1-acetic acid) and glacial acetic acid and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Single-crystal structural analysis shows that I displays an interesting heterometallic 3D coordination framework constructed from 2D praseodymium-oxygen layers and [Cu(Bpdc)2]3? and [CuCl(Bpdc)]2? pillars. The photofluorescence properties of I have been investigated. 相似文献
995.
Niu JL Hao XQ Gong JF Song MP 《Dalton transactions (Cambridge, England : 2003)》2011,40(19):5135-5150
Aryl-based pincer metal complexes with anionic terdentate ligands have been widely applied in organic synthesis, organometallic catalysis and other related areas. Synthetically, the most simple and convenient method for the construction of these complexes is the direct metal-induced C(aryl)-H bond activation, which can be fulfilled by choosing the appropriate functional donor groups in the two side arms of the aryl-based pincer preligands. In this perspective, we wish to summarize some results achieved by our group in this context. Successful examples include symmetrical chiral bis(imidazoline) NCN pincer complexes with Ni(II), Pd(II) and Pt(II), bis(phosphinite) and bis(phosphoramidite) PCP pincer Pd(II) complexes, unsymmetrical (pyrazolyl)phosphinite, (amino)phosphinite and (imino)phosphinite PCN pincer Pd(II) complexes, chiral (imidazolinyl)phosphinite and (imidazolinyl)phosphoramidite PCN pincer complexes with Ni(II) and Pd(II) as well as unsymmetrical (oxazolinyl)amine and (oxazolinyl)pyrazole NCN' pincer Pd(II) complexes. Among them, the P-donor containing complexes are efficiently synthesized by the "one-pot phosphorylation/metalation" method. The obtained symmetrical and unsymmetrical pincer complexes have been used as catalysts in Suzuki-Miyaura reaction (Pd), asymmetric Friedel-Crafts alkylation of indole with trans-β-nitrostyrene (Pt) as well as in asymmetric allylation of aldehyde and sulfonimine (Pd). In the Suzuki couplings conducted at 40-50 °C, some unsymmetrical Pd complexes exhibit much higher activity than the related symmetrical ones which can be attributed to their faster release of active Pd(0) species resulting from the hemilabile coordination of the ligands. Literature results on the synthesis of some related pincer complexes as well as their activities in the above catalytic reactions are also presented. 相似文献
996.
Shao DD Niu JL Hao XQ Gong JF Song MP 《Dalton transactions (Cambridge, England : 2003)》2011,40(35):9012-9019
Chiral 1,3-bis(2'-imidazolinyl)benzenes 1a-e easily undergo direct nickelation at the C2 position of the central benzene ring via the C-H bond activation in the reaction with anhydrous NiCl(2) giving neutral NCN pincer nickel(II) complexes 2a-e in 40-87% yields. Treatment of the nickel pincers 2a or 2c with AgBF(4) in CH(3)CN-CH(2)Cl(2) afforded the cationic nickel pincers 3a or 3c in good yields. All the complexes were characterized by elemental analysis, (1)H, (13)C NMR, and IR spectra. Molecular structures of the neutral complexes 2a, 2b and 2c as well as the cationic complex 3c have been determined by X-ray single-crystal diffraction. The cationic nickel pincers 3 are found to be effective catalysts for the Michael addition of ethyl 2-cyanopropionate to methyl vinyl ketone in the presence of i-Pr(2)NEt base with a catalyst loading of 5 mol% even at -78 °C, producing the adduct in >99% yield after 24 h albeit with no ee. 相似文献
997.
Shen H Wang H Zhou C Niu JZ Yuan H Ma L Li LS 《Dalton transactions (Cambridge, England : 2003)》2011,40(36):9180-9188
Here we report a new "green" method to synthesize Zn(1-x)Cd(x)Se (x = 0-1) and stable red-green-blue tricolor Zn(1-x)Cd(x)Se core/shell nanocrystals using only low cost, phosphine-free and environmentally friendly reagents. The first excitonic absorption peak and photoluminescence (PL) position of the Zn(1-x)Cd(x)Se nanocrystals (the value of x is in the range 0.005-0.2) can be fixed to any position in the range 456-540 nm. There is no red or blue shift in the entire reaction process. Three similar sizes of alloyed Zn(1-x)Cd(x)Se nanocrystals with blue, green, and yellow emissions were successfully selected as cores to synthesize high quality blue, green, and red core/shell nanocrystal emitters. For the synthesis of core/shell nanocrystals with a high quantum yield (QY) and stability, the selection of shell materials has been proven to be very important. Therefore, alternative protocols have been used to optimize thick shell growth. ZnSe/ZnSe(x)S(1-x) and CdS/Zn(1-x)Cd(x)S have been found as an excellent middle multishell to overcoat between the alloyed Zn(1-x)Cd(x)Se core and ZnS outshell. The QYs of the as-synthesized core/shell alloyed Zn(1-x)Cd(x)Se nanocrystals can reach 40-75%. The Cd content is reduced to less than 0.1% for Zn(1 -x)Cd(x)Se core/shell nanocrystals with emissions in the range 456-540 nm. More than 15 g of high quality Zn(1-x)Cd(x)Se core/shell nanocrystals were prepared successfully in a large scale, one-pot reaction. Importantly, the emissions of such thick multishell nanocrystals are not susceptible to ligand loss and stability in various physiological conditions. 相似文献
998.
A one-pot domino synthesis of photochromic 2,2-diarylphenanthro-(9,10)-[2H]-[1,4]-oxazines in excellent yield is described starting with acrylic acid derivatives. The reaction mechanism was studied by ReactIR and UV-vis. The cascade sequence of the reactions involves five transformations, namely, acyl azide formation, Curtius rearrangement, arsonium ylide formation, aza-Wittig, and final cyclization to the title compounds. 相似文献
999.
Nanostructured noble metals exhibit an intense optical near field due to surface plasmon resonance, therefore promising widespread
applications and being of interest to a broad spectrum of scientists, ranging from physicists, chemists, and materials scientists
to biologists. A wealth of research is available discussing the synthesis, characterization, and application of noble metal
nanoparticles in optical sensing. However, with respect to the sensitivity of the frequency and width of these surface plasmon
resonance modes to the particle’s shape, size, and environment, in nearly every case, success strongly depends on the availability
of highly stable, adhesive, and sensitive nanoparticles. This undoubtedly presents a challenging task to nanofabrication.
The past decade has witnessed fascinating advances in this field, in particular, the construction of oxide-based hybrid plasmonic
interfaces to overcome the problem addressed above by (1) coating the metallic nanostructures with thin overlayers to form
sandwiched structures or (2) embedding metallic nanostructures in a dielectric matrix to obtain metal/dielectric matrix nanocomposite
films. In this critical review, we focus on recent work related to this field, beginning with a presentation of hybrid films
with enhanced structural and optical stability, readily and selectively designed using chemical and physical techniques. We
then illustrate their interesting optical properties and demonstrate exciting evidence for the postulated application in surface
plasmon sensing fields. Finally, we survey the work remaining to be done for that potential to be realized. 相似文献
1000.
Ordered TiO2 nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and
catalysis. This present study exploited a new functional application of the ordered TiO2 nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO2 nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron
capture detection. Ordered TiO2 nanotube arrays exhibited excellent merits on the pre-concentration of organochlorine pesticides and lower detection limits
of 0.10, 0.10, 0.10, 0.098, 0.0076, 0.0097, 0.016, and 0.023 μg L−1 for α-HCH, β-HCH, γ-HCH, δ-HCH, p,p’-DDE, p,p’-DDD, o,p’-DDT, and p,p’-DDT, respectively, were achieved. Four real water samples were used for validation, and the spiked recoveries were in the
range of 78–102.8%. These results demonstrated that the developed micro-solid phase equilibrium extraction using ordered TiO2 nanotube arrays would be very constructive and have a great beginning with a brand new prospect in the analysis of environmental
pollutants. 相似文献