In this article, we present the significant influence of the substitution pattern of carbazole on the thermal stability of carbazole-containing platinum(II)-polyyne polymers. A series of the studies on the dynamic and isotherm conditions revealed a better thermal stability for the 3,6-carbazole based platinum(II)-polyyne polymer (36CbzPtP), where alkynes were located at the p-phenylene positions relative to the carbazole nitrogen atom, compared to that for the 2,7-carbazole based counter polymer (27CbzPtP), where the alkynes were located at the m-phenylene positions relative to the carbazole nitrogen atom. On the other hand, the thermogravimetrymass spectrometry-Fourier transform infrared technique applied to the two polymers revealed the same degradation mechanism, which probably involved the thermal decomposition of triethyl phosphine moieties and which was followed by the C C scission of hexadecyl chains. The carbazole moieties eventually underwent degradation when the temperature exceeded 415 C. Molecular modeling showed that polymer 27CbzPtP formed a linear structure, whereas polymer 36CbzPtP adopted a curved structures; this led to different packing modes of the polymer chains. This structural difference affected the efficiency of the initial degradation event of the triethyl phosphine groups. The curved structures of 36CbzPtP sterically protected the triethyl phosphine groups; this led to an increased thermal stability over that of 27CbzPtP.
Dinaphtho[2,1-b:1′,2′-d]thiophene (DNT) is one of the “dynamic thiahelicenes” that is obtained as a racemate due to its low energy barrier for enantiomerization. Careful evaluation of both the metastable DNT film...
Self-polycondensation of 3-iodocarbazole derivatives in the presence of CuI catalysts produces the corresponding 3,9-carbazole-based polymers. Unsubstituted poly(3,9-carbazole) P2 has a limited solubility, whereas poly(3,9-carbazole) P1 with a tert-butyl group at the 6-position of the carbazole is soluble in common organic solvents. These polymers are regarded as an extended form of polyaniline. However, contrary to polyaniline, they are thermally and chemically stable owing to the highly twisted structure between adjacent repeat units. In addition, P1 is highly stable when applying potentials of up to 1.50 V. Due to the high stability toward oxidation, the cast films of these polymers display well-defined visible fluorescence in their neutral states. When the films are exposed to nitro-aromatic vapors (modeled by nitro-explosives), energy transfer induced fluorescent quenching occurs. Upon exposure of the quenched films to air, the fluorescence is restored. Overall, the substituted P1 film exhibits better sensing abilities than the unsubstituted P2 film due to the bulky tert-butyl groups.
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