Synthesis and Photophysical Properties of the 4‐(Biphenyl‐4‐yl)‐2,6‐bis(4‐iodophenyl)pyrylium Ion

Álvaro, Mercedes; Aprile, Carmela; Carbonell, Esther; Ferrer, Belén; Garcı́a, Hermenegildo

doi:10.1002/ejoc.200500997

Cited by 15 publications

(39 citation statements)

References 13 publications

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“…Emission quantum yields for optically matched solutions (optical density = 0.4) were calculated by using the reported value for the fluorescence of TPBF 4 in acetonitrile (F fl = 0.55). [33,34] Fluorescence lifetimes were measured by single-photon counting by using a hydrogen lamp running at a frequency of 20 kHz. Temporal decays were fitted to a single exponential decay to obtain the emission half-lifetime.…”

Section: Methodsmentioning

confidence: 99%

“…[42] The quantum yield (F) of the two emissions was determined by taking the emission intensity of TPBF 4 as the standard value (F fl = 0.55 in acetonitrile). [33,34] By using this F fl value, the fluorescence of TPBF 4 in aqueous solution at pH 1 was determined. The F fl value for TP + in water was very similar to that of the fluorescence in acetonitrile.…”

Section: It Is Known That Tpmentioning

confidence: 99%

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Specific Binding Effects for Cucurbit[8]uril in 2,4,6‐Triphenylpyrylium–Cucurbit[8]uril Host–Guest Complexes: Observation of Room‐Temperature Phosphorescence and their Application in Electroluminescence

Montes‐Navajas

Teruel

Corma

et al. 2008

Chemistry A European J

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2,4,6-Triphenylpyrylium (TP(+)) forms host-guest complexes with cucurbiturils (CBs) in acidic aqueous solutions. (1)H NMR spectroscopic data indicates that complexation takes place by encapsulation of the phenyl ring at the four position within CB. Formation of the complex with CB[6] and CB[7] leads to minor shifts in the fluorescence wavelength maximum (lambda(fl)) or quantum yield (Phi(fl)). In sharp contrast, for complexes with CB[8], the emission results in the simultaneous observation of fluorescence (lambda(fl)=480 nm, Phi(fl)=0.05) and room-temperature phosphorescence (lambda(ph)=590 nm, Phi(ph)=0.15). The occurrence of room-temperature phosphorescence can be used to detect the presence of CB[8] visually in solution. Molecular modeling and MM2 molecular mechanics calculations suggest that this effect arises from locking the conformational mobility of the 2- and 6-phenyl rings as a result of CB[8] encapsulation. The remarkably high room-temperature phosphorescence quantum yield of the TP(+)@CB[8] complex has been advantageously applied to develop an electroluminescent cell that contains this host-guest complex. In contrast, analogous cells prepared with TP(+) or TP(+)@CB[7] fail to exhibit electroluminescence.

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Section: Methodsmentioning

confidence: 99%

Section: It Is Known That Tpmentioning

confidence: 99%

Specific Binding Effects for Cucurbit[8]uril in 2,4,6‐Triphenylpyrylium–Cucurbit[8]uril Host–Guest Complexes: Observation of Room‐Temperature Phosphorescence and their Application in Electroluminescence

Montes‐Navajas

Teruel

Corma

et al. 2008

Chemistry A European J

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“…in 1960 . This study and several subsequent studies that focused on the effect of substituents on the appearance of the absorption spectra came to two key conclusions : (1) The absorption spectra of pyrylium cations can be characterized by two chromophores one with its transition dipole oriented along the pseudo‐ x ‐axis passing through carbons 2 and 6 and the other lying along the C 2 axis passing through the aryl group on carbon 4 and the oxygen atom ; (Scheme ) and (2) Both of these transitions are charge transfer transitions involving migration of electron density from the aryl rings to the pyrylium core. Examples of how substituent effects can provide evidence for these two conclusions are illustrated in Scheme .…”

Section: Resultsmentioning

confidence: 88%

Synthesis, Characterization, Photophysics and Photochemistry of Pyrylogen Electron Transfer Sensitizers

Clennan

Liao

2013

Photochem & Photobiology

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A series of new dicationic sensitizers that are hybrids of pyrylium salts and viologens has been synthesized. The electrochemical and photophysical properties of these "pyrylogen" sensitizers are reported in sufficient detail to allow rationale design of new photoinduced electron transfer reactions. The range of their reduction potentials (+0.37-+0.05 V vs SCE) coupled with their range of singlet (48-63 kcal mol(-1)) and triplet (48-57 kcal mol(-1)) energies demonstrate that they are potent oxidizing agents in both their singlet and triplet excited states, thermodynamically capable of oxidizing substrates with oxidation potentials as high as 3.1 eV. The pyrylogens are synthesized in three steps from readily available starting materials in modest overall 11.4-22.3% yields. These sensitizers have the added advantages that: (1) their radical cations do not react on the CV timescale with oxygen bypassing the need to run reactions under nitrogen or argon and (2) have long wavelength absorptions between 413 and 523 nm well out of the range where competitive absorbance by most substrates would cause a problem. These new sensitizers do react with water requiring special precautions to operate in a dry reaction environment.

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“…39-44 However, this process will not likely occur here since TP + , either in its ground or excited state, is an electron acceptor. 45 For the sake of comparison we have also prepared an analogous material (TP@MCM-41) that was obtained following the exact same preparation procedure as TP@mpTiO 2 , but using TEOS exclusively in the absence of titania nanoparticles during the synthesis. TP@MCM-41 has already been reported in the literature.…”

Section: Photophysics Of Tp@mptiomentioning

confidence: 99%

Long-lived (minutes) photoinduced charge separation in a structured periodic mesoporous titania containing 2,4,6-triphenylpyrylium as guest

et al. 2008

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2,4,6-Triphenylpyrylium (TP(+)), an electron acceptor, has been included inside the channels of two ordered mesoporous titania (mpTiO(2)). MpTiO(2) contain anatase nanoparticles (3-5 nm) templated by cetyltrimethylammonium and differ by the presence or absence of silica domains as binders of the structure. UV irradiation of TP-mpTiO(2) gives rise to a strong EPR signal. This behaviour was not observed for related materials in which TP(+) was included inside the channels of MCM-41 or the cavities of zeolite Y. Also, transient spectroscopy shows remarkable differences between TP(+) included in mpTiO(2) (charge separation) and in porous silicates (triplet excited state). Based on EPR and laser flash spectroscopic evidence, the occurrence of photo-induced electron transfer from TiO(2) as the donor to TP(+) as the acceptor leading to a long-lived (minutes at room temperature) charge separated state is proposed.

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Synthesis and Photophysical Properties of the 4‐(Biphenyl‐4‐yl)‐2,6‐bis(4‐iodophenyl)pyrylium Ion

Cited by 15 publications

References 13 publications

Specific Binding Effects for Cucurbit[8]uril in 2,4,6‐Triphenylpyrylium–Cucurbit[8]uril Host–Guest Complexes: Observation of Room‐Temperature Phosphorescence and their Application in Electroluminescence

Specific Binding Effects for Cucurbit[8]uril in 2,4,6‐Triphenylpyrylium–Cucurbit[8]uril Host–Guest Complexes: Observation of Room‐Temperature Phosphorescence and their Application in Electroluminescence

Synthesis, Characterization, Photophysics and Photochemistry of Pyrylogen Electron Transfer Sensitizers

Long-lived (minutes) photoinduced charge separation in a structured periodic mesoporous titania containing 2,4,6-triphenylpyrylium as guest

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