174735-02-5Relevant articles and documents
Synthesis of derivatives of phenanthrene and helicene by improved procedures of photocyclization of stilbenes
Talele, Harish R.,Gohil, Monik J.,Bedekar, Ashutosh V.
, p. 1182 - 1186 (2009)
An improved method has been developed for photocyclization of stilbene to construct phenanthrenes and benzo[c]phenanthrenes. This reaction is promoted by iodine while tetrahydrofuran is used as an efficient and inexpensive scavenger of hydroiodic acid produced during the photocyclization sequence. In another process, cyclohexene is used as a reagent for dehydrogenation step in place of THFI2.
Exploring the Photocyclization Pathways of Styrylthiophenes in the Synthesis of Thiahelicenes: When the Theory and Experiment Meet
Baciu, Bianca C.,Vergés, José Antonio,Guijarro, Albert
, p. 5668 - 5679 (2021)
The introduction of thiophene rings to the helical structure of carbohelicenes has electronic effects that may be used advantageously in organic electronics. The performance of these devices is highly dependent on the sulfur atom topology, so a precise knowledge of the synthetic routes that may afford isomeric structures is necessary. We have studied the photocyclization pathway of both 2- and 3-styrylthiophenes on their way to thiahelicenes by experiment and theory. To begin with, the synthesis of stereochemically well-defined 2- and 3-styrylthiophenes allowed us to register first, and simulate later, the UV-vis electronic spectra of these precursors. This information gave us access through time-dependent density functional theory calculations to the very nature of the excited states involved in the photocyclization step and from there to the regio- and stereochemical outcome of the reaction. For the widely known case of a 2-styrylthiophene derivative, the expected naphtho[2,1-b]thiophene type of ring fusion was predicted and experimentally observed by synthesis. On the contrary, 3-styrylthiophene derivatives have been seldom used in synthetic photocyclizations. Among the two possible structural outcomes, only the naphtho[1,2-b]thiophene type of ring fusion was found to be mechanistically sound, and this was actually the only compound observed by synthesis.
The role of electron-transporting Benzo[f]quinoline unit as an electron acceptor of new bipolar hosts for green PHOLEDs
Seo, Junseok,Park, So-Ra,Kim, Mina,Suh, Min Chul,Lee, Jihoon
, p. 959 - 966 (2018/11/26)
We prepared three new compounds [3,6-di(9H-carbazol-9-yl)phenanthrene (3,6-DCP), 2,9-di(9H-carbazol-9-yl)benzo[f]quinoline (2,9-DCBQ), and 3,9-di(9H-carbazol-9-yl)benzo[f]-quinoline (3,9-DCBQ)] containing phenanthrene or benzo[f]quinoline as an electron-withdrawing moiety and a carbazole as electron-donating moiety, respectively, as bipolar hosts for green phosphorescent organic light emitting diodes (PHOLEDs). We intentionally substituted nitrogen atom to the C-3 position of phenanthrene moiety to prepare benzo[f]quinolinegroup. And, we found that it allowed better electron transporting behavior than the phenanthrene moiety. Meanwhile, the benzo[f]quinoline/phenanthrene core moieties significantly improved the thermal stability of those host materials, which exhibited glass transition and decomposition temperatures of 132–139 and 395–427 °C, respectively. The green PHOLEDs which were fabricated with those host materials showed the lowest operating voltage of 4.7 V at 1000 cd/m2 when we used 3,9-DCBQ. Very interestingly, it has an asymmetric structure with completely separated HOMO and LUMO in space. In contrast, 3,6-DCP having phenanthrene and carbazole moieties showed much higher operating voltage of 6.1 V which imply that replacing nitrogen at the C-3 position of phenanthrene improves carrier transport, that is, electron transporting behavior. As a result, the 3,9-DCBQ-based PHOLED showed the best overall performance, exhibiting current and power efficiencies of 48.5 cd/A and 20.6 lm/W, respectively.
Expeditious synthesis of helicenes using an improved protocol of photocyclodehydrogenation of stilbenes
Talele, Harish R.,Chaudhary, Anju R.,Patel, Parthiv R.,Bedekar, Ashutosh V.
experimental part, p. 15 - 37 (2011/06/19)
An improved procedure has been developed for photodehydrocyclization of stilbenes for the synthesis of phenanthrenes and helicenes. This procedure involves the use of THF as a scavenger of hydriodic acid produced during iodine mediated photodehydrocyclization. The use of THF is advantageous due to its higher boiling point, lower cost and easy availability as compared to propylene oxide. The method is applied to synthesize a number of phenanthrenes and helicenes. ARKAT-USA, Inc.
