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201.
Brazeau AL DiLabio GA Kreisel KA Monillas W Yap GP Barry ST 《Dalton transactions (Cambridge, England : 2003)》2007,(30):3297-3304
The ligand exchange of guanidinate ligands between metal centres can play an important role in guanidinate chemistry, and ligand exchange between aluminium centres will form a dimeric intermediate. The synthesis and characterization of the dimer [Me(2)NC(N(i)Pr)(2)](2)Al(2)Cl(4) is reported here: compound crystallizes with a twisted boat conformation of its dimer ring. This compound decomposes to monomers at room temperature over four days, or within 18 hours at 90 degrees C. We undertook a detailed computational characterization of the reaction pathway, which supported the dimer structure and subsequent monomer formation. The ligand exchange route was also exploited for the synthesis of [MeC(N(i)Pr)(2)](2)AlCl, [EtC(N(i)Pr)(2)](2)AlCl, [MeC(N(i)Pr)(2)](2)GaCl, and [Me(2)NC(N(i)Pr)(2)](2)GaCl. 相似文献
202.
The alkylation of a chelating bis(carbene) complex of CrCl(2) yields an unusual bimetallic complex featuring a short Cr-Cr distance, novel ligand coordination, and CH(3) ligand exchange. 相似文献
203.
Fang YQ Wong WQ Yap YW Orner BP 《Combinatorial chemistry & high throughput screening》2007,10(8):635-651
Stem cell-based technologies have the potential to help cure a number of cell degenerative diseases. Combinatorial and high throughput screening techniques could provide tools to control and manipulate the self-renewal and differentiation of stem cells. This review chronicles historic and recent progress in the stem cell field involving both pluripotent and multipotent cells, and it highlights relevant cellular signal transduction pathways. This review further describes screens using libraries of soluble, small-molecule ligands, and arrays of molecules immobilized onto surfaces while proposing future trends in similar studies. It is hoped that by reviewing both the stem cell and the relevant high throughput screening literature, this paper can act as a resource to the combinatorial science community. 相似文献
204.
Shyamapada Shit Joy Chakraborty Anamika Das Glenn P. A. Yap M. S. El. Fallah Samiran Mitra 《Structural chemistry》2007,18(3):317-323
A one-dimensional (1-D) copper(II) coordination polymer [Cu(maleate)(2,2′-bipyridyl)]
n
·2H2O has been synthesised. Single crystal X-ray diffraction study reveals that maleate ion bridges two adjacent copper(II) centres
along the chain in a syn–anti fashion. A complete cryomagnetic investigation of the title complex correlates well with the distorted square pyramidal geometry
of the central copper(II) ion and bridging nature of the maleate. A τ value of 0.26 indicates the distortion towards tbp coordination allowing the magnetic orbital to acquire some character leading to a weak antiferromagnetic interaction having J = −0.26 cm−1. The complex has also been firmly established from several other instrumental techniques like Fourier transform infrared
(FT-IR) and EPR spectroscopies. 相似文献
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207.
Ryan A. Baldwin Hamid Rahbarnoohi Leonidas J. Jones Andrew T. McPhail Richard L. Wells Peter S. White Arnold L. Rheingold Glenn P. A. Yap 《Heteroatom Chemistry》1996,7(6):409-416
As(Si1BuMe2)3 (1) was prepared by the salt-elimination reaction between (Na/K)3As and 1BuMe2SiCl. Mixing LiAs(SiMe3)2 with Ph3SiCl (1:1) yielded As(SiMe3)2(SiPh3) (2) in a good crystalline yield. Reaction of 2 (1:1) with Et3Ga gave the expected Lewis acid-base adduct Et3Ga · As(SiMe3)2(SiPh3) (3). The 1:1 mole ratio reaction of In(SePh)3 with As(SiMe3)3 resulted in a ligand redistribution around the indium and arsenic centers to afford As(SePh)3 (4) in a low yield. The solid-state structures of 1–4 have been established by single-crystal X-ray analysis. Crystal data for 1, monoclinic space group P 21/c, with a = 11.112(2), b = 17.453(2), c = 14.199(2) Å, β = 114.89° for Z = 4; 2, orthorhombic space group P c21n, with a = 9.236(1), b = 16.612(2), c = 16.803(4) Å for Z = 4; 3, monoclinic space group P 21/c, with a = 16.799(1), b = 11.199(2), c = 19.413(3) Å, β = 112.22(1) for Z = 4; 4, trigonal space group R &3macr;, with a = 12.863(5), c = 18.96(1) Å for Z = 6. © 1996 John Wiley & Sons, Inc. 相似文献
208.
209.
介绍和评述弹性湍流的产生及其对于微混合效率的影响等问题上的若干研究进展. 弹性湍流和惯性湍流具有类似的流场特征,但引发机理有所不同. 惯性湍流产生的原因是惯性引起的Reynolds应力,而弹性湍流则是由弹性应力所引起的. 鉴于在微流动中,惯性力可忽略不计,因此牛顿流体的混合变得十分困难. 此时可在流体中加入微量高分子聚合物以生成黏弹性流体. 由黏弹性流体所引发的弹性湍流在提高流体微混合的效率上可发挥重要作用. 相似文献
210.
Dong Z Karpowicz RJ Bai S Yap GP Fox JM 《Journal of the American Chemical Society》2006,128(44):14242-14243
Described is the design, synthesis, and characterization of abiotic, single-stranded metallofoldamers that adopt helical secondary structures upon metal complexation. The absolute helicity is determined by stereocenters at the ends of the structures and is enforced by the steric influence and hydrogen bonding ability of esters in the backbone of the foldamer. Folding of the structures is characterized in the solid state by X-ray crystallography and in solution by specific rotation, CD spectroscopy, and NMR spectroscopy. 相似文献