796843-29-3Relevant academic research and scientific papers
Wurster's blue-type cation radicals framed in a 5,10-Dihydrobenzo[a] indolo[2,3-c]carbazole (BIC) Skeleton: Dual electrochromism with drastic changes in UV/Vis/NIR and fluorescence
Suzuki, Takanori,Sakano, Yuto,Tokimizu, Yusuke,Miura, Youhei,Katoono, Ryo,Fujiwara, Kenshu,Yoshioka, Naoki,Fujii, Nobutaka,Ohno, Hiroaki
, p. 1841 - 1846 (2014/07/08)
Electron-donating dihydrobenzindolocarbazoles (BICs) 1 a-c, which adopt planar disk-shaped geometries, were prepared by gold(I)-catalyzed cyclization as a key step. Due to the presence of a 1,4-phenylenediamine (PD) moiety in the framework, they undergo reversible one-electron oxidation to the corresponding Wurster's Blue (WB)-type species that exhibits NIR absorptions up to λ=1200 nm. In the case of the N,N -dimethyl derivative, cation radical 1 c+. is stable enough to be isolated as a salt and X-ray analysis indicated paraquinoid-type bond alternation in the WB core unit, whereas the bond lengths in the peripheral benzene rings are identical to those in the neutral donor. Upon electrochemical interconversion, the redox pairs of 1 a-c and 1 a-c+. exhibited an electrochromic response in the UV/Vis/NIR region, which was accompanied by a drastic change in the fluorescence spectrum because only neutral donors 1 a-c are highly emissive (ΦF: 0.7-0.8). Potential for change: Both UV/Vis/NIR and fluorescence can be reversibly modified by application of electric potential to the highly fluorescent π-extended p-phenylenediamines with disk-shaped geometries to form stable cation radical species (see figure).
Synthesis of phenanthrenes and polycyclic heteroarenes by transition-metal catalyzed cycloisomerization reactions
Mamane, Victor,Hannen, Peter,Fuerstner, Alois
, p. 4556 - 4575 (2007/10/03)
Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted phenanthrenes on exposure to catalytic amounts of either PtCl2, AuCl, AuCl3, GaCl3 or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-complexation of the alkyne unit followed by interception of the resulting η2-metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-phenanthrenes or into the isomeric 9-halo-phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.
