Observed Phosphorescence and Singlet-Triplet Absorption in <i>s</i>-Triazine and Trimethyl-<i>s</i>-Triazine

Paris, J. P.; Hirt, R. C.; Schmitt, R. G.

doi:10.1063/1.1701100

Cited by 25 publications

(6 citation statements)

References 5 publications

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“…Phosphorescence decay in all three solvents could be fitted by a single exponential, and lifetimes of a few milliseconds were observed. Phosphorescence for this compound has previously been reported in an EPA (2 ethanol, 5 i-pentane, 5 Et 2 O) glass, and shown to have a maximum around 455 nm and lifetime 0.44 s. [29] At present, the reason for the difference in lifetimes in this work and in our previous studies is not clear. Phosphorescence has also been observed for 2 and 3 in 3MP glasses at 77 K. The spectrum for 2 ( Figure 3) shows a broad band with maximum at 450 nm (2.76 eV).…”

Section: Phosphorescence Of Triazinesmentioning

confidence: 76%

“…A wide variety of both theoretical (semiempirical to ab initio level) and experimental studies have been carried out on their electronic transitions. [28][29][30][31][32][33][34][35][36][37][38][39] However, there are still many unanswered questions regarding the nature of the excited states. Therefore, within the framework of a wider project aiming to elucidate the molecular mechanisms of photodegradation of different water pollutants, we report the results of a joint computational and luminescence study of the low-lying singlet and triplet states of three different sym-triazines (see Scheme 1), and discuss their role in the photodegradation mechanism.…”

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confidence: 99%

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On the Low‐Lying Excited States of sym‐Triazine‐Based Herbicides

et al. 2005

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We report a joint computational and luminescence study on the low-lying excited states of sym-triazines, namely, 1,3,5-triazine (1) and the ubiquitous herbicides atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I and 2 were computed at the TD-DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates were determined. The predictions from CASPT2 calculations are in good agreement with the experimental results obtained from the luminescence studies and allow the interpretation of different absorption and emission features.

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Section: Phosphorescence Of Triazinesmentioning

confidence: 76%

mentioning

confidence: 99%

On the Low‐Lying Excited States of sym‐Triazine‐Based Herbicides

et al. 2005

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“…Since the triplet state of 1 − 3 cannot be observed directly with our methods, the triplet energy of 1 was estimated from the triplet energies that are available for 1,3,5-triazine in the literature. Hochstrasser and Zewail 15 report 82.6 kcal/mol, whereas Paris et al …”

Section: Resultsmentioning

confidence: 95%

Mechanistic Studies of Photoacid Generation from Substituted 4,6-Bis(trichloromethyl)-1,3,5-triazines

Pohlers¹,

Scaiano²,

Sinta³

et al. 1997

Chem. Mater.

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The photochemistry and photophysics of 2-methyl-(1), 2-(2′-furylethylidene)-( 2), and 2-[(4′methoxy)styryl]-4,6-bis(trichloromethyl)-1,3,5-triazine (3), three compounds that find application as photoacid generators in photoresist formulations, have been investigated under conditions of direct excitation and using various phenothiazine derivatives as photosensitizers. C-Cl bond cleavage is confirmed by laser flash photolysis as the primary photochemical step in the direct photolysis of these compounds; the chlorine atoms formed in this reaction can be detected by complexation with chloride anions or benzene. In the case of 1, this photodissociation occurs with a lifetime of <20 ns. The quantum yield of bond breaking for 1 after direct excitation as determined by laser flash photolysis and steady-state irradiations was found to be 30-40 times greater than for 2 and 3. The mechanism under sensitized conditions involves electron transfer from the excited phenothiazines to the triazines as the primary photochemical step; the rate constants for excited-state quenching exceed 10 9 M -1 s -1 for the T 1 state and 10 10 M -1 s -1 for the S 1 state. The rate constants correlate with the free energy for electron transfer estimated from the excited-state energies and the oxidation potential of the sensitizers.

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“…As demonstrated in model compound studies, the peak at 280 nm has contributions from both the B band of the π−π* transition of benzene and the R band of the n−π* transition of triazine. The B band of benzene and the R band of triazine appear at 255 nm (ε = 215) and 270 nm (ε = 881), respectively . The molar extinction coefficient of the former is smaller.…”

Section: Resultsmentioning

confidence: 99%

UV, Luminescence, and FTIR Characterization of Cure Reaction in Bisphenol A Dicyanate Ester Resin

Sung

2002

Macromolecules

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To develop cure monitoring techniques for bisphenol A dicyanate ester (BPADCY) resin, UV, fluorescence, phosphorescence, and IR spectra were investigated. UV−vis spectra during the cure reaction indicates that the cyclotrimerization of cyanate esters to form triazine rings is the principal reaction, as supported by IR spectroscopic results. During the cure reaction, very strong luminescence emission has been found. Fluorescence emission intensity around 420 nm first increases, followed by decrease with a small red shift as the cure reaction proceeds. The aromatically substituted cyanurates formed during the cure reaction and their inner filter effect are responsible for the observed emission and its trend in intensity. In-situ fluorescence characterization showed similar results for the catalyzed cure reaction with cobalt acetylacetonate/nonylphenol as well as bisphenol A catalyzed resin in comparison to purified BPADCY, except for the faster rate in fluorescence spectral change. Phosphorescence emission of polycyanate resins appears at a 440 nm, which is about 20 nm longer than that of fluorescence. The phosphorescence lifetime has been found to be about 20 ms at room temperature and remains relatively unchanged throughout the cure reaction. FTIR in situ cure studies of BPADCY monomer indicates a linear relationship between the consumption rate of cyanate ester groups and the formation rate of the substituted triazine rings. Fluorescence changes are correlated to the extent of cure by IR technique.

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Observed Phosphorescence and Singlet-Triplet Absorption in s-Triazine and Trimethyl-s-Triazine

Cited by 25 publications

References 5 publications

On the Low‐Lying Excited States of sym‐Triazine‐Based Herbicides

On the Low‐Lying Excited States of sym‐Triazine‐Based Herbicides

Mechanistic Studies of Photoacid Generation from Substituted 4,6-Bis(trichloromethyl)-1,3,5-triazines

UV, Luminescence, and FTIR Characterization of Cure Reaction in Bisphenol A Dicyanate Ester Resin

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