Solid‐State Radical C−H Trifluoromethylation Reactions Using Ball Milling and Piezoelectric Materials
作者:Yadong Pang、Joo Won Lee、Koji Kubota、Hajime Ito
DOI:10.1002/anie.202009844
日期:2020.12.7
The application of piezoelectricity for the generation of trifluoromethyl (CF3) radicals is reported together with the development of a method for the mechanochemical C−H trifluoromethylation of aromatic compounds. As compared to conventional solution‐based approaches, this mechanoredox C−H trifluoromethylation enables cleaner and more sustainable access to a wide range of trifluoromethylated N‐heterocycles
Crystalline structure and phase behavior of N-alkylated polypyrrole comb-like polymers
作者:Haixia Wang、Xu Han、Haifeng Shi、Xingxiang Zhang、Lu Qi、Dujin Wang
DOI:10.1039/c4ce00722k
日期:——
We report the crystalline structure and phase behavior of a series of comb-like polymers (PPy-Cn), which were prepared via N-alkylation reactions between a pyrrole monomer and n-alkyl bromides (n = 18–26). Analysis by temperature-dependent X-ray diffraction and Fourier transform infrared spectroscopy (FTIR), as well as differential scanning calorimetry reveals that the crystal structure, thermal events and packing mode are affected by PPy backbones, which exhibit stronger rigidity than those of previously reported comb-like polymers. Remarkably, variable-temperature (VT)-FTIR proves the formation of orthorhombic phase at very low temperature, while VT-wide-angle X-ray diffraction only presents the hexagonal phase, illustrating that FTIR is a very sensitive tool for analyzing the micro-packing mode of molecular chains. The enhanced side-chain crystallizable carbon atoms indicate that PPy polymeric backbones play a negative role in the regular packing of nano-crystallites formed by alkyl groups.
Electrochemical polymerization in Langmuir-Blodgettmultilayers of amphiphilic pyrrole derivatives resulted in anisotropic conducting thin films having alternate conducting and insulating layered structure.
The synthesis and non-linear optical properties of (N-alkylpyrrol-2-yl)squaraine derivatives. Part 1
作者:Daniel E. Lynch、Uwe Geissler、Ian R. Peterson、Mathias Floersheimer、Roland Terbrack、Li Feng Chi、Harald Fuchs、Nicolas J. Calos、Barry Wood、Colin H. L. Kennard、G. John Langley
DOI:10.1039/a604111f
日期:——
The synthesis of a soluble poly(pyrrolylsquaraine) was achieved by
N-alkylation of the pyrrole nucleus with
1-bromooctadecane and subsequent condensation with squaric acid.
Bis(1-octadecylpyrrol-2-yl)- squaraine was also produced and found to
exist in a variety of inseparable isomeric forms. When deposited as
Langmuir–Blodgett monolayers on hydrophilic substrates, these dyes
exhibit second harmonic generation (SHG) with
deff = 0.5 ±
0.1 pm V-1 for both. For comparison,
bis(3,5-dimethyl-1-octadecylpyrrol-2-yl)squaraine was synthesised and
revealed a higher SHG activity of
deff = 1.8 ±
0.2 pm V-1. Poly(1-octadecylpyrrolylsquaraine)
is the first alternating donor–acceptor polymer to give SHG.