NMR relaxationtime studies of poly(Nvinyl carbazole) and sorbedO2 effectsThe dielectric relaxation spectrum of poly(N-vinylcarbazole) (PVK) and poly(3-chloro-N-vinylcarbazole) (CLPVK) have been investigated in the temperature range -180-+ 240 DC. Four relaxations are observed in PVK. The a relaxation (225°C) is associated with the glass transition of the polymer. On the basis of oxygen-sorption experiments, the y relaxation (--60°C) has been associated with a rotationallibration of the pendant carbazole group. It is also speculated on the basis of this work that an off-axis dipole is induced in the carbazole moiety by the sorbed O 2 producing the dielectrically active motion about the symmetry axis of the carbazole moiety. The 13 (-80°C) and the Il (--160°C) relaxations are assigned as carbazole wagging motions and localized backbone motions, respectively. These assignments are based on comparative work in the literature.PACS numbers: 77.40.
This work describes the synthesis and properties of ad icyanomethylene-substituted indolo[3,2-b]carbazole diradical ICz-CN. This quinoidal system dimerises almost completely to (ICz-CN) 2 ,w hich contains two long C(sp 3)À C(sp 3) s-bonds between the dicyanomethylene units. The minor open-shell ICz-CN component in the solid-state mixture was identified by EPR spectroscopy.C yclic voltammetry and UV-visible spectroelectrochemical data, as well as comparison with reference monomerI Cz-Br reveal that the nature of the one-electrono xidation of (ICz-CN) 2 at ambient temperature and ICz-CN at elevated temperature is very similar in all these compounds due to the prevailing localization of their HOMO on the ICz backbone. The peculiar cathodic behaviour reflects the coexistence of (ICz-CN) 2 and ICz-CN. The involvement of the dicyanomethylene groupss tabilizes the close-lying LUMO and LUMO + 1o f(ICz-CN) 2 and especially ICz-CN comparedt oI Cz-Br,r esulting in ad istinctive cathodic response at low overpotentials. Differently from neutralI Cz-CN, its radicala nion and dianion are remarkably stable under ambient conditions. The UV/Vis(-NIR) electronic transitions in parent (ICz-CN) 2 and ICz-CN and their different redox forms have been assigned convincingly with the aid of TD-DFT calculations. The s-bond in neutral(ICz-CN) 2 is cleaved in solution and in the solid-state upon soft external stimuli (temperature, pressure), showing as trong chromism from light yellow to blue-green. Notably,i nt he solid state, the monomeric diradical species is predominantly formed under high hydrostatic pressure (> 1GPa).
Air and moisture stable diaryl dithiocarbamate salts, Ar2NCS2Li, result from addition of CS2 to Ar2NLi, the latter being formed upon deprotonation of diarylamines by nBuLi. Oxidation with K3[Fe(CN)6] affords the...
Copper diaryl-dithiocarbamate (DTC) complexes have been prepared including Cu(II) species, [Cu(S2CNAr2)2], and Cu(I) species [Cu{S2CN(p-tolyl)2}]n and [Cu{S2CN(p-tolyl)2}(PPh3)2] with some examples being characterised by single crystal diffraction. CV measurements show that,...
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