- A Simply Synthesized, Tough Polyarylene with Transient Mechanochromic Response
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A simple and high-yielding route to tough polyarylenes of the type poly(meta,meta,para-phenylene) (PmmpP) is developed. PmmpP is tough even in its as-synthesized state which has an intermediate molar mass of Mw≈60 kg mol?1 and exhibits outstanding mechanical properties at further optimized molecular weight of Mw=96 kg mol?1, E=0.9 GPa, ?=300 %. Statistical copolymers with para,para-spiropyran (SP) are mechanochromic, and the toughness allows mechanochromism to be investigated. Strained samples instantaneously lose color upon force release. DFT calculations show this phenomenon to be caused by the PmmpP matrix that allows build-up of sufficiently large forces to be transduced to SP, and the relatively unstable corresponding merocyanine (MC) form arising from the aromatic co-monomer. MC units covalently incorporated into PmmpP show a drastically reduced half life time of 3.1 s compared to 4.5 h obtained for SP derivatives with common 6-nitro substitution.
- Kempe, Fabian,Brügner, Oliver,Buchheit, Hannah,Momm, Sarah N.,Riehle, Felix,Hameury, Sophie,Walter, Michael,Sommer, Michael
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- Preparation method of high-purity tris(dibenzylideneacetone)dipalladium (0)
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The invention discloses a preparation method of high-purity tris(dibenzylideneacetone)dipalladium (0). The method includes 1, in a nitrogen atmosphere, adding ligand dibenzylideneacetone, palladium dichloride and anhydrous sodium acetate to anhydrous ethanol that is in a stirring state to carry out a heating reaction, and performing filtering to obtain solid bis(dibenzylideneacetone)palladium (0); 2, in a nitrogen atmosphere, adding the solid bis(dibenzylideneacetone)palladium (0) obtained in the step 1 to acetone that is in a stirring state, washing a retained product after filtering, and drying the washed retained product to obtain the tris(dibenzylideneacetone)dipalladium (0). The preparation method has the advantages that the bis(dibenzylideneacetone)palladium (0) is prepared from the anhydrous ethanol, the dibenzylideneacetone, the palladium dichloride and the anhydrous sodium acetate at first, and then is treated by an acetone solution to obtain the tris(dibenzylideneacetone)dipalladium (0), and accordingly, the obtained tris(dibenzylideneacetone)dipalladium (0) has high purity.
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Paragraph 0024; 0027-0029; 0032-0034; 0037-0038
(2019/10/04)
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- Enantioselective Synthesis of Homoallylic Azides and Nitriles via Palladium-Catalyzed Decarboxylative Allylation
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Azides and nitriles are important building blocks for the synthesis of nitrogen-containing bioactive compounds. The first example of enantioselective palladium-catalyzed decarboxylative allylation of α-azido and cyano β-ketoesters is reported. Indanone derivatives were obtained in 50-88% yield/77-97% ee and 46-98% yield/78-93% ee for azide and nitrile substituents, respectively. The required starting materials were synthesized in one step from ketoesters via electrophilic azidation and cyanation using benziodoxole hypervalent iodine reagents. The products could be easily converted into useful nitrogen-containing building blocks, such as triazoles, amides, or α- and β- amino ketones.
- Vita, Maria Victoria,Caramenti, Paola,Waser, Jerome
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supporting information
p. 5832 - 5835
(2015/12/11)
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