13629-22-6Relevant articles and documents
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Pinck,Hilbert
, p. 377,379 (1946)
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The Electrochemical Reduction of Fluorenone Tosylhydrazone: Evidence Consistent with Formation of the Tosyl Nitrene Anion Radical
Galen, Dean A. Van,Barnes, James H.,Hawley, M. Dale
, p. 2544 - 2550 (1986)
Fluorenone tosylhydrazone (Fl=NNHTs) undergoes one-electron reductive dehydrogenation in DMF-0.1 F (n-Bu)4NClO4 to give hydrogen and its conjugate base Fl=NN-Ts as products.Fl=NN-Ts is subsequently reduced at more negative potential to a dianion radical (Fl=NNTs dianion radical) that is stable on the cyclic voltammetric time scale.On the coulometric time scale or in the presence of added proton donors (pKa ca.29), Fl=NNTs dianion radical decomposes to give FlHNH2 and TsNH2 as the principal products.A pathway is proposed for the reaction of Fl=NNTs dianion radical which involves rate-determining proton abstraction by the nitrogen atom α to the fluorene moiety.Cyclic voltammetric and chronoamperometric data are presented which are consistent with the formation of the tosyl nitrene anion radical as a short-lived, unobserved intermediate.
Experimental and Computational Studies on Stepwise [3+2]-Cycloadditions of Diaryldiazomethanes with Electron-Deficient Dimethyl (E)- and (Z)-2,3-Dicyanobutenedioates
Mlostoń, Grzegorz,Celeda, Ma?gorzata,Jasiński, Radomir,Heimgartner, Heinz
, p. 422 - 431 (2019)
Electron-deficient dimethyl (E)- and (Z)-2,3-dicyanobutenedioates (dimethyl dicyanofumarate and dicyanomaleate, respectively) react with diaryldiazomethanes at room temperature under spontaneous evolution of N2. The type of the products strongly depends on the structure of the diazo compound. Whereas diphenyldiazomethane and its bis(4-methoxy) derivative yield cyclopropanes, sterically crowded 5-diazo-5H-dibenzo[a,d]cycloheptane derivatives afford either the dimer of the carbene formed via N2 elimination or the adduct of the carbene onto the starting diazo compound. The course of the studied reactions is rationalized by stepwise mechanisms initiated by the formation of a C–N bond. A cascade of reactions leads to the corresponding cyclopropanes or to release of a carbene species. The formation of a pyrazole via [3+2]-cycloaddition (32CA) is observed only in reactions with (trimethylsilyl)diazomethane, which behaves similar to the parent diazomethane. The proposed mechanisms were analyzed computationally using the DFT method.
Tuning the rotation rate of light-driven molecular motors
Bauer, Jurica,Hou, Lili,Kistemaker, Jos C. M.,Feringa, Ben L.
, p. 4446 - 4455 (2014)
Overcrowded alkenes are among the most promising artificial molecular motors because of their ability to undergo repetitive light-driven unidirectional rotary motion around the central C=C bond. The exceptional features of these molecules render them highly useful for a number of applications in nanotechnology. Many of these applications, however, would benefit from higher rotation rates. To this end, a new molecular motor was designed, and the isomerization processes were studied in detail. The new motor comprises a fluorene lower half and a five-membered-ring upper half; the upper-half ring is fused to a p-xylyl moiety and bears a tert-butyl group at the stereogenic center. The kinetics of the thermal isomerization was studied by low-temperature UV-vis spectroscopy as well as by transient absorption spectroscopy at room temperature. These studies revealed that the tert-butyl and p-xylyl groups in the five-membered-ring upper half may be introduced simultaneously in the molecular design to achieve an acceleration of the rotation rate of the molecular motor that is larger than the acceleration obtained by using either one of the two groups individually. Furthermore, the new molecular motor retains unidirectional rotation while showing remarkably high photostationary states.
Electrochemical Studies of the Reduction of Fluorenone Triphenylphosphazine. Formation of the Stable Dimeric Dianion, (FlN2)2(2-)
Herbranson, Dale E.,Theisen, F. J.,Hawley, M. Dale,McDonald, Richard N.
, p. 2544 - 2549 (1983)
The electrochemical reduction of fluorenone triphenylphosphazine (Fl=NN=PPh3) in N,N-dimethylformamide - 0.1 M (n-Bu)4NClO4 is initially a one-electron process which affords the corresponding anion radical.Fl=NN=PPh3(-*) is unstable on the cyclic voltammetric time scale, decomposing by nitrogen-phosphorus bond cleavage (k = 0.45 s-1 at T = 1 deg C) to give PPh3 and 9-diazofluorene anion radical (FlN2(-*)).The latter species then reacts rapidly with either FL=NN=PPh3 or FlN2(-*) to give a stable dimeric dianion.The dianion, which was shown from chronoamperometric and coulometric gas-pressure studies to have the empirical formula (FlN2)2(2-), is oxidized in successive one-electron steps to (FlN2)2 which slowly loses N2 on the cyclic voltammetric time scale to give fluorenone azine (Fl=NN=Fl).The structure of the dimeric species is considered to be the tetraazatriene Fl=NN=NN=Fl.No evidence was obtained for the formation of the carbene anion radical, Fl(-*), via the loss of N2 from FlN2(-*).
Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N-Phenylfluorenylidene)acridane
Matsuo, Yutaka,Wang, Ya,Ueno, Hiroshi,Nakagawa, Takafumi,Okada, Hiroshi
supporting information, p. 8762 - 8767 (2019/05/29)
(N-Phenylfluorenylidene)acridane (Ph-FA) compounds with electron-withdrawing and -donating substituents (H, MeO, Ph, NO2, Br, F) at the para position of the phenyl group were successfully synthesized by Barton–Kellogg reactions of N-aryl thioacridones and diazofluorene. By using the substituent on the nitrogen atom to alter the electronic properties, both the folded and twisted conformers of p-NO2-C6H4-FA could be crystallographically characterized, which enabled the charge transfer from the electron-donating acridane moiety to the electron-accepting fluorenylidene moiety to be understood. Ground-state mechanochromism, thermochromism, vapochromism, and proton-induced chromism were demonstrated between the folded and twisted conformations of the conformers. Protonation and chemical oxidation of Ph-FA gave two stable acridinium compounds, namely, the fluorenylacridinium and acridinium radical cations. The present study will contribute to the development of functional dyes and organic semiconductors.
