Excimer fluorescence spectra of pyrene derivatives

1963 ◽  
Vol 19 (2) ◽  
pp. 401-410 ◽  
Author(s):  
J.B. Birks ◽  
L.G. Christophorou
2010 ◽  
Vol 88 (3) ◽  
pp. 217-227 ◽  
Author(s):  
Mark Ingratta ◽  
Manoj Mathew ◽  
Jean Duhamel

A series of polystyrenes randomly labeled with 1-pyrenebutanol were prepared by copolymerizing styrene and 1-pyrenebutylacrylate yielding the CoBuE–PS series. Solutions of CoBuE–PS were prepared in nine organic solvents having viscosities ranging from 0.36 to 5.5 mPa·s and the fluorescence spectra and pyrene monomer and excimer fluorescence decays were acquired. Analysis of the fluorescence spectra yielded the IE/IM ratio, whereas analysis of the fluorescence decays with the fluorescence blob model (FBM) yielded the parameters N blobo , <kblob × Nblob> , and k blobo . These parameters were compared to those obtained with two other series of pyrene-labeled polystyrenes, which had been studied earlier, namely CoA–PS and CoE–PS where pyrene was attached to the polymer backbone via a methylamide and benzyl methylether linker, respectively. Although the parameters IE/IM, N blobo , <kblob × Nblob>, and k blobo took different values according to the specific nature of the linker connecting pyrene to the polystyrene backbone, they exhibited trends that were quite similar for all the pyrene-labeled polystyrene constructs. The excellent agreement between the parameters retrieved for the three different types of pyrene-labeled polystyrenes suggests that the FBM accounts satisfyingly for differences in the nature of the label used, while still retrieving information pertinent to the polymer of interest.


1964 ◽  
Vol 20 (1) ◽  
pp. 15-21 ◽  
Author(s):  
J.B. Birks ◽  
J.B. Aladekomo

Observations have been made of the concentration dependence of the fluorescence spectra of solutions of 1:2-benzanthracene and fifteen of its hydrocarbon derivatives. All of the compounds, except the 9,10-dim ethyl derivative, exhibit dim er emission at higher concentrations. The lower excited states, 1 L b and 1 L a , satisfy Förster’s conditions for fluorescent dim er formation. The factors determining the relative quantum yield of excimer fluorescence are discussed. The different types of crystal fluorescence spectra shown by the compounds are explained in terms of excimer formation in the crystal lattice.


Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1107 ◽  
Author(s):  
Anna Makal ◽  
Joanna Krzeszczakowska ◽  
Roman Gajda

The crystal structure of 1-(pyren-1-yl)but-2-yn-1-one ( 1 a , a polynuclear aromatic hydrocarbon displaying enhanced luminescence in the solid state, has been re-determined at several pressures ranging from atmospheric up to 3 GPa using a Diamond Anvil Cell (DAC). These experiments were augmented by periodic DFT calculations at pressures up to 4.4 GPa. UV-Vis fluorescence of 1 a at non-ambient pressures has also been investigated. The crystal structure consists of infinite π -stacks of anti-parallel 1 a molecules with discernible dimers, which may exemplify aggregates formed by pyrene derivatives in solution and thin films, and is predominantly stabilized by dispersion. The average inter-planar distance between individual molecules within π -stacks decreases with pressure in the investigated range. This results in piezochromic properties of 1 a : a red-shift of sample color, as well as a bathochromic shift of fluorescence with pressure (by ca. 100 nm at 3.5 GPa). Two-component fluorescence spectra support the hypothesis that at least two types of excimers are involved in the electronic excitation processes in crystalline 1 a .


The excimer fluorescence spectra of pure single pyrene crystals were observed from 4 to 353 °K. The data are analysed to determine the vibrational zero-point energy of the excimer (= 90 cm -1 ), the force constants of the excited state (= 1.93 x 10 5 dyn/cm) and ground state (= 3.25 x 10 5 dyn/cm) of the dimer, and the equilibrium intermolecular separation (= 3.34 Å) of the excimer. The repulsive intermolecular potential, the excimer energy, and the attractive excimer interaction potential, V' = 51330 - 1.136 x 10 6 / r 3 (cm -1 ) are determined as functions of the intermolecular separation r (Å). V' is shown to be consistent with an exciton resonance state originating from the 1 B a state of the pyrene molecule.


Observations were made of the fluorescence spectra of cyclohexane and n -hexane solutions of benzene, toluene, p -xylene and mesitylene and of the pure liquids as a function of concentration and temperature under standard excitation conditions. Excimer fluorescence is observed in benzene, toluene and mesitylene, and there is evidence for excimer formation in p -xylene. The data are analysed to determine the fluorescence quantum efficiencies, the rate parameters and other properties of the monomer-excimer systems. The following values are obtained for the excimer binding energy B ; benzene, 0.22 eV; toluene, 0.17 eV; p -xylene, > 0.11 eV; and mesitylene, 0.12 eV. The results are consistent with the excimer potential model, and the reduction in B in the methyl derivatives is attributed to steric hindrance.


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