We describe the spin polarization–induced chirogenic electropolymerization of achiral 2-vinylpyridine, which forms a layer of enantioenhanced isotactic polymer on the electrode. The product formed is enantioenriched in asymmetric carbon polymer. To confirm the chirality of the polymer film formed on the electrode, we also measured its electron spin polarization properties as a function of its thickness. Two methods were used: First, spin polarization was measured by applying magnetic contact atomic force microscopy, and second, magnetoresistance was assessed in a sandwich-like four-point contact structure. We observed high spin-selective electron transmission, even for a layer thickness of 120 nm. A correlation exists between the change in the circular dichroism signal and the change in the spin polarization, as a function of thickness. The spin-filtering efficiency increases with temperature.
The preparation of various bis‐N‐heterocyclic carbene (bis‐NHC) complexes of rhodium and their application in the hydroaminomethylation of vinyl arenes was investigated. Various reaction parameters such as solvent, temperature, and pressure were tested, and the optimized protocol was applied to a wide variety of vinyl arenes and amines to afford the corresponding amines in good yields with high selectivity towards the branched product. The bis‐NHC‐based catalyst demonstrated superior reactivity and selectivity compared to catalysts containing bidentate phosphine or monodentate NHC ligands. A triethoxysilyl‐functionalized bis‐NHC ligand was immobilized on magnetic nanoparticles and then utilized to bind a rhodium catalyst. The resulting catalytic system was successfully employed in hydroaminomethylation reactions. The catalyst exhibited excellent reactivity, high selectivity, and was simply recovered from the reaction medium by applying an external magnetic field.
Mechanophores have become a very useful tool to study mechanical stress at the molecular level, as well as a method for detection of mechanical damage. However, optical signals from such...
Fluorinated polymers are unique in their properties AND, as a consequence, have found a variety of particular applications ranging from the pharmaceutical industry to paints, energy‐storage devices, microelectronics, and even optical devices and, as such, became ubiquitous in our everyday life. This polymer family presents high stability toward acids, bases, and organic solvents and typically maintains their properties even at very high temperatures. In addition, they are resistant to oxidation, are electric insulators, possess low surface tension, and can present excellent optical transmitting properties. As with other fluorinated molecules, fluorinated polymers are synthetic, and therefore, a rich chemistry was developed in order to create a large variety of materials, both to understand their properties AND to address specific needs in different applications. In this chapter, the chemistry behind monomer synthesis, polymerization, and polymers are described, looking at the intended and accidental discoveries, all of which were key to advance modern‐life technologies.
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