Mechanistic study of the quenching of naphthalene fluorescence by cis,trans-1,3-cyclooctadiene

Murov, Steven; Yu, Loh-Sheng.; Giering, Linda P.

doi:10.1021/ja00794a031

Cited by 10 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For these samples we saw more red emission from the acceptors, as a result of the reduced collisional quenching of the red emitting fluorophores. reported for the fluorescence quenching of naphthalene by organic dienes in cyclohexane, 41 and amines in water. 42 While this comparison was not entirely valid because of the massive differences in composition/complexity it did indicate that the fluorescence quenching behavior was very similar.…”

Section: Resultsmentioning

confidence: 99%

Low Temperature Fluorescence Studies of Crude Petroleum Oils

Owens

Ryder

2011

Energy Fuels

View full text Add to dashboard Cite

We have studied the low-temperature (133−298 K) fluorescence emission of crude petroleum oils using a combination of steady-state and time-resolved measurements. This was done to first see if we could generate linear correlations between oil composition information and the fluorescence measurements, and second to better understand how static and dynamic quenching affect fluorescence emission. It was observed that the fluorescence intensity and lifetime of the crude oils increased rapidly with decreasing temperature down to the freezing point and then either remained constant or surprisingly began to decrease slightly. These changes could not be correlated accurately with the compositional data available. However, despite the very large variations in sample composition, it was found that these lifetimetemperature changes followed simple Arrhenius and Eyring behavior. For the cold liquid phase, an Arrhenius model enabled the calculation of an intrinsic lifetime, the magnitude of which was inversely related to the degree of static quenching. The low values of the calculated activation energies (4.6 to 19.2 kJmol − 1) implied that in the liquid phase, non-radiative decay was primarily diffusion based quenching. At the lowest temperatures, when all samples have solidified, the lifetime data followed Eyring like behavior, giving typical enthalpy and entropy values of −1 kJmol − 1 and from −67 to −93 JK − 1 mol − 1 respectively. The Eyring model was used to describe the non-radiative decay mechanism arising from vibrational coupling from the fluorophores to the surrounding matrix. This modeling of the temperature dependence of fluorescence lifetime has provided a clearer, quantitative picture of the fluorescence quenching processes in crude petroleum oils.

show abstract

Section: Resultsmentioning

confidence: 99%

Low Temperature Fluorescence Studies of Crude Petroleum Oils

Owens

Ryder

2011

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…The solvent was removed under reduced pressure. Chromatography on a silica gel column using benzene-n-hexane (1:3) and recrystallization from ethanol gave 110 mg (73%) of the valence tautomer 17 as colorless needles: mp 148-150°; ir (KBr) 1445, 990, 775, and 690 cm-'; nmr (CDC13) at 100 MHz 1.38 (ddd, 1 H, j = 13.0, 10.0, and 4.0 Hz), 1.89 (ddd, 1 H, J = 13.0, 10.0, and 2.0 Hz), 2.54 (dd, 1 H, J = 10.0 and 2.0 Hz), 3.02 (d, 1 H, J = 2.0 Hz), 3.36 (dd, 1H,;= 10.0 and 2.0 Hz), 3.94 (td, 1 H, J = 10.0 and 4.0 Hz), 5.97 (d, 1 H, J = 2.4 Hz), 6.10 (d, 1 H, J = 2.4 Hz), 7.04 (m, 14 H). Anal.…”

Section: Methodsmentioning

confidence: 99%

“…The mass spectrum showed a molecular ion peak at m/e 362 with the base peak and at m¡e 270 (1,3-diphenylisobenzofuran). The 100-MHz nmr spectrum (CDCI3) exhibited signals at 1.38 (ddd, 1 H, He-6, J = 13.0, 10.0, and 4.0 Hz), 1.89 (ddd, 1 H, Ha-6, J = 13.0, 10.0, and 2.0 Hz), 2.54 (dd, 1 , H-5, J = 10.0 and 2.0 Hz), 3.02 (d, 1 , H-2, J = 2.0 Hz), 3.36 (dd, 1 H, H-l, J = 10.0 and 2.0 Hz), 3.94 (td, 1 , H-7, / = 10.0 and 4.0 Hz), 5.97 (d, 1 H, H-4, J = 2.4 Hz), 6.10 (d, 1 , H-3, J = 2.4 Hz) and 7.04 (m, 14 H, aromatic). The deshielding effect of the oxygen bridge was observed by the nmr for the methine protons (H-l and H-7).29 Catalytic hydrogenation of 17 yielded a dihydro derivative 18 after uptake of 1 equiv of hydrogen.…”

mentioning

confidence: 99%

“…The similar deshielding effect of the oxygen bridge was observed only for 10 (see Experimental Section). Thus, the former two adducts were concluded to be exo [6 + 4] (4) and endo [6 + 4] cycloadducts (5), which are not allowed to arise in a concerted fashion from an excited state by orbital symmetry theory. 23 The nmr spectrum showed two kinds of bridgehead methine protons for 6 at 3.39 (H-5, allylic) and 3.82 (H-l, bisallylic) and for 7 at 3.08 and 3.50, suggesting that the structures lacked an element of symmetry.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Photochemical and thermal cycloaddition reactions of 1,3-diphenylisobenzofuran with cycloheptatriene

Sasaki¹,

Kanematsu²,

Hayakawa³

et al. 1975

J. Am. Chem. Soc.

View full text Add to dashboard Cite

“…A number of rearrangements that qualify as exciplex isomerizations have been identified (34)(35)(36)(37)(38)(39). Importantly these photoisomerizations are induced by electron donor-…”

Section: Photosensitizat Ion Involving Exciplexesmentioning

confidence: 99%