Absorption and fluorescence of pyrylium salts

Haucke, G.; Czerney, Peter; Cebulla, F.

doi:10.1002/bbpc.19920960706

Cited by 36 publications

(18 citation statements)

References 17 publications

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“…In general, 2,4,6-trisubstituted PS with three identical substituents, e.g., 2,4,6-triaryl PS, as well as some blocked PS are considered as two-dimensional chromophoric systems with X and Y absorption bands. [16][17][18][19][20][21][22][23] The photophysical and nonlinear properties of PS dimers that tend to be formed in low polarity solvents have been investigated in detail by Markovitsi and coworkers. 20,[23][24][25] Kossanyi and co-workers have reported the observation of dual emission from blocked PS and explained it in terms of two excited states with different geometries.…”

Section: Introductionmentioning

confidence: 99%

Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence

et al. 2006

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A series of 6-styryl-2,4-diphenylpyrylium salts exhibiting dual fluorescence has been investigated by fluorescence up-conversion in conjunction with quantum chemical calculations. The short-wavelength emission is due to an excited state localized on the pyrylium fragment and the long-wavelength emission arises from a charge-transfer state delocalized over the whole molecule. The two fluorescing states do not exhibit a precursor-successor relationship. The rise time of the short-wavelength fluorescence is smaller than 200 fs, and that of the long-wavelength emission depends on the electron-donating property of the styryl group substituent. The rise is almost prompt with the weaker donors but is slower, wavelength and viscosity dependent with the strongest electron-donating group. A model involving a S 2 /S 1 conical intersection is proposed to account for these observations.

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Section: Introductionmentioning

confidence: 99%

Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence

et al. 2006

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“…The peak absorption wavelengths and corresponding molar absorptivity, along with other optical spectroscopic properties such as photoluminescence spectra and quantum yields in acetonitrile (CH 3 CN) are summarized in Table 2. According to the previously reported studies of 2,4,6-triphenylpyrylium perchlorate, two absorption peaks at 417 nm and 369 nm are observed in CH 2 Cl 2 [7,32]. The absorption spectrum of salt 1 in CH 3 CN (Fig.…”

Section: Optical Spectroscopic Propertiesmentioning

confidence: 66%

“…1) is similar in appearance to that of the 2,4,6-triphenylpyrylium perchlorate in CH 2 Cl 2 , but its peak absorption ( max ) exhibited hypsochromic shifts caused by the increased solvent polarity. Similarly, salts 2-4 also showed hypsochromic shifts in acetonitrile when compared with those in CH 2 Cl 2 [32]. Table 2, Fig.…”

Section: Optical Spectroscopic Propertiesmentioning

confidence: 75%

Synthesis, optical spectroscopy and laser potential of pyrylium tosylates

Koh

Lee

Ciulei

et al. 2018

Journal of Molecular Structure

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Safe and inexpensive methods for synthesis of a series of four substituted 2,4,6-triphenylyrylium tosylate salts with different substituents are reported. The synthesis methods use ptoluenesulfonic acid monohydrate instead of conventional acid catalysts including perchloric acid or boron trifluoride diethyl etherate that pose explosion danger and difficult storage problems, respectively. The chemical structures of these salts were established using FTIR, 1 H and 13 C NMR spectroscopic techniques and elemental analysis. Thermogravimetric analysis (TGA) showed that these salts have good thermal stability, and differential scanning calorimetry (DSC) analysis showed that they have lower melting transitions than the corresponding tetrafluoroborate and perchlorate salts. Solutions of the salts in organic solvents (such as acetonitrile and methanol) absorbed strongly in the blue-near-ultraviolet spectral range and emitted efficiently in the blue-green spectral range depending on the substituents in 2-and 6positions of phenyl groups. The fluorescence quantum yields of the salts ranged from 0.33 to 0.56. Under intense ultrashort laser pumping, an acetonitrile solution of the salt, 2,4,6triphenylpyrylium tosylate, the salt with the highest quantum yield, demonstrated stimulated emission and laser action with only nominal feedback.

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“…2). These bands are usually denominated as y for 355 nm and x for 405 nm [15][16][17]. To find the most adapted basis set, PBE1PBE functional was fixed and the basis set was gradually changed from 6-31G to 6-311++G**.…”

Section: Computation Of Singlet Transitions Energiesmentioning

confidence: 99%

Dual-cure Photo-thermal Initiating System for Cationic Polymerization of Epoxy under LED Visible Light

Lecompère

Allonas

Maréchal³

et al. 2017

J. Photopol. Sci. Technol.

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The development of new initiating systems for epoxy resin curing remains a highly interesting topic, especially for composites and coatings applications. Among all the possibilities existing to cure an epoxy resin, recent works have highlighted novel photo-thermal cationic initiators based on pyrylium salts. Interestingly, absorption spectra of trisubstituted pyrylium salts extend up to the visible region, a feature that was not exploited yet. In this paper, the pyrylium salts absorption spectra were predicted using Density Functional Theory. It is shown that accurate prediction of UV-Vis spectra can be made at relatively moderate level of theory. Then, visible photopolymerization of epoxy resin was performed under mercury lamp and 395 nm LED. Finally, a photoinduced thermal frontal polymerization of a thick sample of epoxy resin was performed by prompting the reaction at 395 nm. This work opens new opportunity in the polymerization of thick materials such as for composites.

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Absorption and fluorescence of pyrylium salts

Cited by 36 publications

References 17 publications

Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence

Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence

Synthesis, optical spectroscopy and laser potential of pyrylium tosylates

Dual-cure Photo-thermal Initiating System for Cationic Polymerization of Epoxy under LED Visible Light

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