33895-27-1Relevant academic research and scientific papers
Systematic investigations on fused π-system compounds of seven benzene rings prepared by photocyclization of diphenanthrylethenes
Fujino, Shota,Yamaji, Minoru,Okamoto, Hideki,Mutai, Toshiki,Yoshikawa, Isao,Houjou, Hirohiko,Tani, Fumito
, p. 925 - 934 (2017/07/10)
We studied the photoproducts of 1-(n-phenanthryl)-2-(m-phenanthryl)ethenes (nEm; n, m = 1, 3 and 9) for understanding photocyclization patterns based on NMR spectroscopy. The crystal structures of the photoproducts were analyzed by X-ray crystallography, and the photophysical features of the photocyclized molecules were investigated based on emission and transient absorption measurements. Phenanthrene derivatives substituted at the 1- and 3-positions were prepared for synthesizing nEm by photocyclization of stilbene derivatives. We obtained four types of primary photoproducts (n@m) from the corresponding nEm. Two of them were found to have racemic molecular structures in the single crystal determined by X-ray crystallography. Besides the primary photoproducts, two types of secondary photoproducts (n@mPP) were isolated. Fluorescence quantum yields and lifetimes of the obtained photoproducts were determined in solution whereas the definite fluorescence quantum yields were obtained in the powder. Observation of the triplet-triplet absorption spectra in solution by laser photolysis techniques showed that intersystem crossing to the triplet state competes with the fluorescence process.
Monoaza[5]helicenes. Part 2: Synthesis, characterisation and theoretical calculations
Abbate, Sergio,Bazzini, Cristina,Caronna, Tullio,Fontana, Francesca,Gambarotti, Cristian,Gangemi, Fabrizio,Longhi, Giovanna,Mele, Andrea,Sora, Isabella Natali,Panzeri, Walter
, p. 139 - 148 (2007/10/03)
The synthesis of four different monoaza[5]helicenes is reported, to complete the whole series of these compounds, so that systematic studies on their properties can be carried out. They were fully characterised via NMR. A theoretical approach to explain w
An Unusual Fluorine Atom Rearrangement in the Photocyclization of 1-Fluorohelicenes
Mallory, Frank B.,Mallory, Clelia W.
, p. 526 - 532 (2007/10/02)
Oxidative photocyclization of 1-fluorohelicene and two of its chlorine-substituted derivatives leads to the formation of 8-fluorobenzoperylenes through an unprecedented inter-ring fluorine atom migration; photoelimination of HF to give benzoperylenes also occurs as a competing process.The rearrangement pathway predominates when the irradiation is carried out at 0 deg C in air-saturated benzene solution containing 10 -3 M iodine; the elimination pathway predominates at higher temperatures or in the absence of either oxygen or iodine.The rearrangement isrationalized by postulating a triplet-state photocyclization to give a dihydrobenzoperylene intermediate, followed by abstraction of the tertiary hydrogen atom from that intermediate to give a radical that subsequently undergoes a fluorine atom shift by an SNi'mechanism.
