- Visible-Light-Driven Halogen Bond Donor Based Molecular Switches: From Reversible Unwinding to Handedness Inversion in Self-Organized Soft Helical Superstructures
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Visible-light-driven molecular switches endowing reversible modulation of the functionalities of self-organized soft materials are currently highly sought after for fundamental scientific studies and technological applications. Reported herein are the des
- Bisoyi, Hari Krishna,Bunning, Timothy J.,Li, Bing-Xiang,Li, Quan,McConney, Michael E.,Wang, Hao
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p. 2684 - 2687
(2020/01/22)
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- P -Toluenesulfonic Acid Induced Conversion of Fluorinated Trimethylsilylethynylanilines into Aminoacetophenones: Versatile Precursors for the Synthesis of Benzoazaheterocycles
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A simple and efficient approach to the synthesis of fluorinated amino-substituted acetophenones in good to excellent yields is reported. The heart of the proposed method consists of conversion of a Me 3 Si-C≡C- moiety into a MeC(=O)- group in the presence of p -tolu ene sulfonic acid (p -TSA) passing a stage of ethynylaniline formation. The reaction is metal-free, proceeds under mild conditions, and uses readily available starting compounds (trimethylsilylarylacetylene derivatives). The reaction provides access to amino-substituted acetophenones, which may serve as precursors for the synthesis of polyfluorinated azaheterocycles, having potential anticarcinogenic activity.
- Politanskaya, Larisa,Tretyakov, Evgeny
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p. 555 - 564
(2017/11/03)
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- General and efficient synthesis of polyfluorinated 2-aminotolans and 2-arylindoles
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It was established here that cross-coupling of polyfluorinated 2-iodoanilines with arylacetylenes in MeCN in the presence catalytic amounts of Pd(PPh3)2Cl2, CuI and Et3N produces the corresponding 2-aminotolans although their yields are decreased from 98% to 40% with increasing fluorination of the substrates. It was shown that the 2-aminotolans with six or fewer fluorine atoms in their rings can be heterocyclised by heating in ethanol containing p-TSA to produce the corresponding polyfluorinated indoles. Cyclisation of tolans containing larger numbers of fluorine atoms in their rings proceeds most efficiently in the presence of KOH, resulting in 2-phenylindoles containing the current maximum of eight fluorine atoms.
- Politanskaya, Larisa V.,Shteingarts, Vitalij D.,Tretyakov, Evgeny V.
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- Shaping crystals with light: Crystal-to-crystal isomerization and photomechanical effect in fluorinated azobenzenes
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Unusually long thermal half-lives of perhalogenated cis-azobenzenes enabled their structural characterization and the first evidence of a crystal-to-crystal cis → trans azobenzene isomerization. Irradiation with visible light transforms a perhalogenated cis-azobenzene single crystal into a polycrystalline aggregate of its trans-isomer in a photomechanical transformation that involves a significant, controllable, and thermally irreversible change of crystal shape. This is the first demonstration of permanent photomechanical modification of crystal shape in an azobenzene.
- Bushuyev, Oleksandr S.,Tomberg, Anna,Friscic, Tomislav,Barrett, Christopher J.
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p. 12556 - 12559
(2013/09/23)
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- Halogen bonding versus hydrogen bonding in driving self-assembly and performance of light-responsive supramolecular polymers
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Halogen bonding is arguably the least exploited among the many non-covalent interactions used in dictating molecular self-assembly. However, its directionality renders it unique compared to ubiquitous hydrogen bonding. Here, the role of this directionality in controlling the performance of light-responsive supramolecular polymers is highlighted. In particular, it is shown that light-induced surface patterning, a unique phenomenon occurring in azobenzene-containing polymers, is more efficient in halogen-bonded polymer-azobenzene complexes than in the analogous hydrogen-bonded complexes. A systematic study is performed on a series of azo dyes containing different halogen or hydrogen bonding donor moieties, complexed to poly(4-vinylpyridine) backbone. Through single-atom substitution of the bond-donor, control of both the strength and the nature of the noncovalent interaction between the azobenzene units and the polymer backbone is achieved. Importantly, such substitution does not significantly alter the electronic properties of the azobenzene units, hence providing us with unique tools in studying the structure-performance relationships in the light-induced surface deformation process. The results represent the first demonstration of light-responsive halogen-bonded polymer systems and also highlight the remarkable potential of halogen bonding in fundamental studies of photoresponsive azobenzene-containing polymers. Copyright
- Priimagi, Arri,Cavallo, Gabriella,Forni, Alessandra,Gorynsztejn-Leben, Mikael,Kaivola, Matti,Metrangolo, Pierangelo,Milani, Roberto,Shishido, Atsushi,Pilati, Tullio,Resnati, Giuseppe,Terraneo, Giancarlo
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experimental part
p. 2572 - 2579
(2012/09/22)
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- 2,3,5,6-Tetrafluorophenylnitren-4-yl: A quartet-ground-state nitrene radical
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Elements of a carbene and a nitrene are linked by a common delocalized π electron in the molecule described here (see picture). The organic high-spin molecule with a quartet ground state could be photochemically generated and spectroscopically characteriz
- Wenk, Hans Henning,Sander, Wolfram
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p. 2742 - 2745
(2007/10/03)
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- C-I STRETCHING VIBRATIONS IN IODOBENZENES
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Comparison of the calculated and experimental IR and Raman spectra of a series of iodobenzenes showed that the C-I stretching vibrations for these compounds correspond to a very highly polarized Raman band 150 - 270 cm-1 (ρ = 0.1).The position of this band depends on the mass of the para substituent and relative position of the fluorine and iodine atoms in the molecule.The UV absorption spectral data indicate an interaction of the iodine atom and para substituents through the ?-system.Opposite substituent effects on the change in intensity of the B-band in the UV spectra of iodobenzenes and tetrafluoroiodobenzenes were noted.
- Fugaeva, O.M.,Korobeinicheva, I.K.,Bardin, V.V.
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p. 2309 - 2311
(2007/10/02)
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