In the present letter, for the first time, the efficacy of hydrotalcite-like layered double hydroxides (LDHs) materials as alternative and novel catalyst precursors for the synthesis of carbon nanotubes (CNTs) via catalytic chemical vapor deposition (CCVD) of acetylene was reported. Nanometer-sized cobalt particles were prepared by calcination of a single molecular LDH precursor containing cobalt (II) and aluminum (III) and following by a process of reduction. Multi-walled CNTs with uniform diameters were obtained using the as-synthesized catalyst in the reaction.
We
report the synthesis and isolation of three new σ-complexes
of Cu(I) in which E–H (E = Al, Zn) σ-bonds are coordinated
to copper. The addition of the main group hydride to a toluene-solvated
Cu(I) complex results in reversible ligand exchange, and the Cu(I)
σ-complexes have been crystallized. Experimental and computational
data provide a wealth of evidence for weak binding of the E–H
bond to Cu(I), which can be ascribed to σ-donation from the
E–H bond into the 4s orbital of copper and back-donation from
copper into the E–H σ* orbital.
Three series of water-soluble semi-rigid thermo-responsive polymers with well-defined molecular weights based on mesogen-jacketed liquid crystal polymers, poly [bis(N-(2-hydroxypropyl) pyrrolidoneand poly[bis(N-hydroxypropyl pyrrolidone) 2-vinylterephthalate] (PHPPVTA) have been synthesized via reversible addition-fragmentation chain transfer polymerization. The steric hindrance effects on liquid crystalline property and thermo-responsive behaviors of semi-rigid water-soluble polymers (P(2-HPPVTA), P(1-M-2-HEPVTA), and PHPPVTA) were carefully investigated. From molecular structure, the steric hindrance of P(1-M-2-HEPVTA) is stronger than that of P(2-HPPVTA). Polarized light microscope and onedimensional wide-angle X-ray diffraction revealed that both the P(2-HPPVTA) and P(1-M-2-HEPVTA) display a columnar nematic phase, indicating that the steric hindrance effect do not affect liquid crystalline behavior of the polymers. The dynamic light scattering results demonstrated that P(1-M-2-HEPVTA) exhibited lower cloud point compared with that of P(2-HPPVTA) at the same mass concentration and the same molecular weight. The more significant molecular weight and concentration dependence on cloud point have been observed in P(2-HPPVTA) solution than in P(1-M-2-HEPVTA) solution. We also discovered that the cloud points of both P(2-HPPVTA) and P(1-M-2-HEPVTA) solution are lower in D 2 O than in H 2 O. It is noted that the cloud point of PM-2 is 9.9 C lower in D 2 O than in H 2 O, much less pronounced than the cloud point difference of PH-2. The differences of thermo-responsive behaviors between P(2-HPPVTA) and P(1-M-2-HEPVTA) were resulted from the steric hindrance effect existed in their side groups.
A Cu(I)-catalysed addition and cyclisation sequence has been developed for the synthesis of (E)-alkylidene pyrrolinone derivatives. The reactions incorporate simple α-keto amides and alkynes as substrates, and employ a commercially available Cu(I) catalyst. The process tolerates good variation of both starting materials, and delivers the desired pyrrolinones in good yields, with high levels of stereocontrol.Scheme 1 Selected examples of natural products and pharmaceutical compounds containing 2-pyrrolinone derivatives. † Electronic supplementary information (ESI) available. See
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