- Spectroscopic study of intermolecular interactions in various oligofluorenes: Precursors of light-emitting polymers
-
A detailed analysis of the optical and photophysical properties of 2,7-bis(phenylene)-9,9-dioctylfluorene (PFP), 2,7-bis(biphenylene)-9,9-dioctylfluorene (BPFBP), 2,7-bis(2-thienyl)-9,9-dioctylfluorene (TFT), and 2,7-bis(2,2-bithien-5-yl)-9,9-dioctylfluorene (BTFBT) in various environments are reported. The optical properties of the free molecules isolated in an alkane matrix are obtained and discussed in terms of the conformation adopted by each derivative in the electronic ground and first excited states. Also, conformational changes are responsible for the optical changes observed at high concentrations in an isopentane glass at 77 K. High quantum yields of all the oligofluorenes at 77 K indicate the absence of quenching effects such as excitonic or aggregation effects. The similar spectral and photophysical properties in matrix and glass environments are explained by the disorder introduced in oligofluorenes by long octyl chains at the C-9 position of the fluorene moiety. To study the effect of intermolecular interactions in the solid state, we recorded the spectra of thin films of these derivatives. The much red-shifted emission band in the solid state cannot be explained by conformational changes and has its origin in the ??-stacking of conjugated oligomers in their relaxed Si state. As an evidence to show the importance of the role played by octyl chains at the C-9 position of the fluorene moiety, we synthesized two new model compounds: one, without octyl chains at the C-9 position of the fluorene moiety, 2,7-bis(2-thienyl)fluorene (TFTWC) and another with more octyl chains, 1,4-bis(9,9-dioctylfluoren-2-yl)phenyl (FPF). The spectral properties of these derivatives have been studied at room temperature and at 77 K. These systems serve as excellent examples to show the effect of intermolecular interactions on optical properties of oligofluorenes.
- Tirapattur, Soujanya,Belleteì?te, Michel,Drolet, Nicolas,Bouchard, Jimmy,Ranger, Maxime,Leclerc, Mario,Durocher, Gilles
-
-
Read Online
- Unveiling Extreme Photoreduction Potentials of Donor-Acceptor Cyanoarenes to Access Aryl Radicals from Aryl Chlorides
-
Since the seminal work of Zhang in 2016, donor-acceptor cyanoarene-based fluorophores, such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), have been widely applied in photoredox catalysis and used as excellent metal-free alternatives to noble metal Ir- and Ru-based photocatalysts. However, all the reported photoredox reactions involving this chromophore family are based on harnessing the energy from a single visible light photon, with a limited range of redox potentials from -1.92 to +1.79 V vs SCE. Here, we document the unprecedented discovery that this family of fluorophores can undergo consecutive photoinduced electron transfer (ConPET) to achieve very high reduction potentials. One of the newly synthesized catalysts, 2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile (3CzEPAIPN), possesses a long-lived (12.95 ns) excited radical anion form, 3CzEPAIPN?-*, which can be used to activate reductively recalcitrant aryl chlorides (Ered ≈ -1.9 to -2.9 V vs SCE) under mild conditions. The resultant aryl radicals can be engaged in synthetically valuable aromatic C-B, C-P, and C-C bond formation to furnish arylboronates, arylphosphonium salts, arylphosphonates, and spirocyclic cyclohexadienes.
- Xu, Jinhui,Cao, Jilei,Wu, Xiangyang,Wang, Han,Yang, Xiaona,Tang, Xinxin,Toh, Ren Wei,Zhou, Rong,Yeow, Edwin K. L.,Wu, Jie
-
supporting information
p. 13266 - 13273
(2021/09/07)
-
- Fluorene derivative and preparation method and application thereof
-
The invention discloses a compound shown as a formula (I) and a preparation method thereof. The two R are the same or different; the two R1 are the same or different; each of R and R1 is independentlyselected from the group consisting of: unsubstituted or
- -
-
Paragraph 0143-0149
(2020/06/30)
-
- Visible-Light-Induced Organocatalytic Borylation of Aryl Chlorides
-
The preparation of arylboronates from unactivated aryl chlorides in a transition-metal-free manner is rather challenging. There are only few examples to achieve this goal by using ultraviolet irradiation. Based on the mechanistic understanding of the diboron/methoxide/pyridine reaction system, we achieved photoactivation of the in situ generated super electron donor and developed a visible-light-induced organocatalytic method for efficient borylation of unactivated aryl chlorides.
- Zhang, Li,Jiao, Lei
-
supporting information
p. 9124 - 9128
(2019/06/17)
-
- Discovery of ledipasvir (GS-5885): A potent, once-daily oral NS5A inhibitor for the treatment of hepatitis C virus infection
-
A new class of highly potent NS5A inhibitors with an unsymmetric benzimidazole-difluorofluorene-imidazole core and distal [2.2.1]azabicyclic ring system was discovered. Optimization of antiviral potency and pharmacokinetics led to the identification of 39 (ledipasvir, GS-5885). Compound 39 (GT1a replicon EC50 = 31 pM) has an extended plasma half-life of 37-45 h in healthy volunteers and produces a rapid >3 log viral load reduction in monotherapy at oral doses of 3 mg or greater with once-daily dosing in genotype 1a HCV-infected patients. 39 has been shown to be safe and efficacious, with SVR12 rates up to 100% when used in combination with direct-acting antivirals having complementary mechanisms.
- Link, John O.,Taylor, James G.,Xu, Lianhong,Mitchell, Michael,Guo, Hongyan,Liu, Hongtao,Kato, Darryl,Kirschberg, Thorsten,Sun, Jianyu,Squires, Neil,Parrish, Jay,Keller, Terry,Yang, Zheng-Yu,Yang, Chris,Matles, Mike,Wang, Yujin,Wang, Kelly,Cheng, Guofeng,Tian, Yang,Mogalian, Erik,Mondou, Elsa,Cornpropst, Melanie,Perry, Jason,Desai, Manoj C.
-
supporting information
p. 2033 - 2046
(2014/04/03)
-
- ANTIVIRAL COMPOUNDS
-
The invention is related to anti-viral compounds, compositions containing such compounds, and therapeutic methods that include the administration of such compounds, as well as to processes and intermediates useful for preparing such compounds.
- -
-
Page/Page column 431
(2010/12/17)
-
- Synthesis of Conjugated Polyrotaxanes
-
A series of conjugated polyrotaxane insulated molecular wires are synthesised by aqueous Suzuki polymerisation, using hydrophobic binding to promote threading of the cyclodextrin units. These polyrotaxanes have conjugated polymer cores based on poly(para-
- Michels, Jasper J.,O'Connell, Michael J.,Taylor, Peter N.,Wilson, Joanne S.,Cacialli, Franco,Anderson, Harry L.
-
p. 6167 - 6176
(2007/10/03)
-