15679-24-0Relevant articles and documents
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Orchin et al.
, p. 1094 (1952)
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Mitchell,R.H.,Carruthers,R.J.
, p. 3054 - 3056 (1974)
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The K-Region in Pyrenes as a Key Position to Activate Aggregation-Induced Emission: Effects of Introducing Highly Twisted N,N-Dimethylamines
Sasaki, Shunsuke,Suzuki, Satoshi,Igawa, Kazunobu,Morokuma, Keiji,Konishi, Gen-Ichi
, p. 6865 - 6873 (2017/07/17)
A new design strategy to activate aggregation-induced emission (AIE) in pyrene chromophores is reported. In a previous report, we demonstrated that highly twisted N,N-dialkylamines of anthracene and naphthalene induce drastic AIE when these donors are introduced at appropriate positions to stabilize the S1/S0 minimum energy conical intersection (MECI). In the present study, this design strategy was applied to pyrene: the introduction of N,N-dimethylamine substituents at the 4,5-positions of pyrene, the so-called K-region, are likely to stabilize MECIs. To examine this hypothesis, four novel pyrene derivatives, which contain highly twisted N,N-dimethylamino groups at the 4- (4-Py), 4,5- (4,5-Py), 1- (1-Py), or 1,6-positions (1,6-Py) were tested. The nonradiative transitions of 4,5-Py are highly efficient (knr = 57.1 × 107 s-1), so that its fluorescence quantum yield in acetonitrile decreases to φfl = 0.04. The solid-state fluorescence of 4,5-Py is efficient (φfl = 0.49). In contrast, 1,6-Py features strong fluorescence (φfl = 0.48) with a slow nonradiative transition (knr = 11.0 × 107 s-1) that is subject to severe quenching (φfl = 0.03) in the solid state. These results underline that the chemistry of the pyrene K-region is intriguing, both from a photophysical perspective and with respect to materials science.
Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
, p. 2301 - 2307 (2007/10/03)
The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
