Ultrafast Photogeneration of a Tetrazolinyl Radical

Kanal, Florian; Schleier, Domenik; Nuernberger, Patrick

doi:10.1002/cphc.201500628

Cited by 7 publications

(12 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The absorption spectrum of TTC in ethanol, which is basically identicalt ot he one in neutral and acidic water as well as in methanol, [26] exhibits as trong band with am aximum at 247 nm (e 247 nm = 32 10 3 Lmol À1 cm À1 )a nd ac haracteristic shoulder around3 20 nm (Figure1a). For PTC in ethanol, the main peak is redshifted to 264 nm (e 264 nm = 65 10 3 Lmol À1 cm À1 assuming quantitative conversion from TTC to PTC), and as eparated band with am aximum at 350 nm and a shoulder around 375 nm is present.…”

Section: Steady-state Spectroscopymentioning

confidence: 70%

“…In the corresponding transient absorption spectra of TTC, [26] both similarities and differences to the ones of PTC are found beyondt he additional presence of stimulated emission. For the dynamics of TTC, two interpretations were given, the first one including an ultrafast openingo ft he tetrazolium ring followed by electron uptake and reclosure to form the TTCC radical, and as econd one without ring opening in which excitedstate absorptions give rise to the sub-nsd ynamics.…”

Section: Assessingconceivable Photoreactionsmentioning

confidence: 89%

“…The non-radiative process competing with fluorescenceissensitivetosolvent polarity (Figure 7). [26]). The transient absorption data does not show ad istinct absorption growing in on the t 1 timescale, but rather a signal peaking around 560 nm remains after severaln anosec-onds together with ab road offset (middle row of Figure 6).…”

Section: Assessingconceivable Photoreactionsmentioning

confidence: 99%

“…[17] Its photochemistry has been studied in detail with absorption spectroscopy, [15,16] electron spin resonance (ESR), [18][19][20][21][22][23] cyclic voltammetry, [21][22][23] and polarography. [26] In aqueous environments, excitation of TTC will yield both 1,3,5-triphenylformazan( TPF) andt he "photo-TTC" cation (PTC), whereas in alcohols only PTC is present after the illumination. The tempo-ral behavioro ft he reaction dynamics of TTCC was investigated with flash photometry [24] and pulsed radiolysis, [25] whereas the formation of TTCC on an anosecondt imescale has recently been reported for various solvents in femtosecondt ransient absorption studies.…”

Section: Introductionmentioning

confidence: 99%

“…The tempo-ral behavioro ft he reaction dynamics of TTCC was investigated with flash photometry [24] and pulsed radiolysis, [25] whereas the formation of TTCC on an anosecondt imescale has recently been reported for various solvents in femtosecondt ransient absorption studies. [26] In aqueous environments, excitation of TTC will yield both 1,3,5-triphenylformazan( TPF) andt he "photo-TTC" cation (PTC), whereas in alcohols only PTC is present after the illumination. [15,16] In contrast to TTC and most tetrazolium compounds, PTC exhibits apronouncedfluorescence [15,27,28] of cerulean appearance.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Ultrafast Dynamics of a Fluorescent Tetrazolium Compound in Solution

et al. 2017

Self Cite

View full text Add to dashboard Cite

Tetrazolium salts are exploited in various fields of research by virtue of their low reduction potentials. Increasingly, associated applications also attend to the photochemical and luminescence properties of these systems. Here, we investigate the photoinduced dynamics of phenyl-benzo[c]tetrazolo-cinnolinium chloride (PTC), one of the very few known fluorescent tetrazolium compounds, by using time-correlated single-photon counting, femtosecond fluorescence upconversion, and ultrafast transient absorption spectroscopy. PTC is generated photochemically by ultraviolet illumination of 2,3,5-triphenyl-tetrazolium chloride (TTC) in various alcohols. Time-resolved fluorescence measurements on PTC with different excitation wavelengths disclose biphasic solvation and vibrational relaxation dynamics. Depending on the solvent, the emission behavior of PTC is characterized by quantum yields on the order of several tens of percent and corresponding excited-state lifetimes of several hundreds of picoseconds. The radiative rate is basically constant for the studied alcohols, whereas the rate of the competing non-radiative process is sensitive to the solvent polarity. Hence, we discuss the possible involvement of intermediate radicals and further presumptive reaction pathways pursued after photoexcitation of PTC.

show abstract

Section: Steady-state Spectroscopymentioning

confidence: 70%

Section: Assessingconceivable Photoreactionsmentioning

confidence: 89%

Section: Assessingconceivable Photoreactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ultrafast Dynamics of a Fluorescent Tetrazolium Compound in Solution

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals

Shu,

Yang,

Rajca

2023

Chem. Rev.

View full text Add to dashboard Cite

Stable radicals and thermally robust high-spin di-and triradicals have emerged as important organic materials due to their promising applications in diverse fields. New fundamental properties, such as SOMO/HOMO inversion of orbital energies, are explored for the design of new stable radicals, including highly luminescent ones with good photostability. A relation with the singlet−triplet energy gap in the corresponding diradicals is proposed. Thermally robust high-spin di-and triradicals, with energy gaps that are comparable to or greater than a thermal energy at room temperature, are more challenging to synthesize but more rewarding. We summarize a number of high-spin di-and triradicals, based on nitronyl nitroxides that provide a relation between the experimental pairwise exchange coupling constant J/k in the high-spin species vs experimental hyperfine coupling constants in the corresponding monoradicals. This relation allows us to identify outliers, which may correspond to radicals where J/k is not measured with sufficient accuracy. Double helical high-spin diradicals, in which spin density is delocalized over the chiral π-system, have been barely explored, with the sole example of such high-spin diradical possessing alternant π-system with Kekuléresonance form. Finally, we discuss a high-spin diradical with electrical conductivity and derivatives of triangulene diradicals.

show abstract

Sensitivity of Isomerization Kinetics of 1,3,5-Triphenylformazan on Cosolvents Added to Toluene

2021

Self Cite

View full text Add to dashboard Cite

Formazan molecules exhibit photochromism because isomerization processes following excitation may occur in both the azo group and the hydrazone group; thus, each formazan may be present in various forms with different colors. The ratio of these forms depends on the illumination conditions and the environment of the formazan with a most incisive sensibility of the thermal anti-syn relaxation of the CN toward slight traces of impurities in toluene solutions, as reported most prominently for 1,3,5-triphenylformazan. Here, we study the latter compound with transient absorption spectroscopy to investigate the role of these traces by adding small amounts of both protic and aprotic cosolvents. Whereas the activation barrier decreases if the binary solvent mixture has a higher polarity, the role of hydrogen bonding can have a reverse impact on the thermal isomerization rate. Both the addition of an aprotic cosolvent and the addition of a protic cosolvent can slow the reaction due to their hydrogen-bond accepting and hydrogen-bond donating properties, respectively. In the case of methanol as a cosolvent, this effect outweighed that of the polarity increase for small concentrations, which was not observed for the fluorinated alcohol hexafluoroisopropanol. The results are explained in the context of a competition between solute−cosolvent and cosolvent−cosolvent hydrogen bonding.

show abstract

Ultrafast Photogeneration of a Tetrazolinyl Radical

Cited by 7 publications

References 39 publications

Ultrafast Dynamics of a Fluorescent Tetrazolium Compound in Solution

Ultrafast Dynamics of a Fluorescent Tetrazolium Compound in Solution

From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals

Sensitivity of Isomerization Kinetics of 1,3,5-Triphenylformazan on Cosolvents Added to Toluene

Contact Info

Product

Resources

About