Induction of Triplet-State Emission of the Transient Proton-Transfer Keto Form of Methyl Salicylate by Heavy-Atom Perturbation†

1998 ◽  
Vol 102 (2) ◽  
pp. 323-328 ◽  
Author(s):  
J. Catalán ◽  
C. Díaz
Keyword(s):  
Proton Transfer ◽  
Triplet State ◽  
Methyl Salicylate ◽  
Heavy Atom ◽  
Keto Form

Löschung der Perylen-Fluoreszenz durch Ag+ -Ionen / Quenching of the Perylene Fluorescence by Ag+-Ions

1983 ◽  
Vol 38 (6) ◽  
pp. 698-700 ◽  
Author(s):  
H. Dreeskamp ◽  
A. Läufer ◽  
M. Zander
Keyword(s):  
Triplet State ◽  
Dynamic Process ◽  
Aromatic Compounds ◽  
Heavy Atom ◽  
Silver Ions ◽  
Intersystem Crossing ◽  
Fluid Solution ◽  
Long Wavelength ◽  
Wavelength Emission ◽  
Atom Effect

The fluorescence of perylene in fluid solution (λ0.0 = 440 nm) is quenched by silver ions in a dynamic process according to a Stern-Volmer kinetics (kq = 2 · 109 [1 • mol-1 · sec-1], in ethanol at 295 K). Simultaneously an unstructured long-wavelength emission (λmax ≈ 470 nm) appears which we assign to a perylene/Ag+ exciplex. A similar emission is observed when other polvcyclic aromatic compounds (PAC) are used, whose fluorescence as in the case of perylene is not easily quenched in an external heavy atom effect by iodopropane (kq ≦ 106). In these cases the excited PAC/Ag+ complex is long-lived enough to emit fluorescence since the intersystem crossing to the triplet system is slow due to the absence of an energetically favorable accepting triplet state

An exceptionally long-lived triplet state of red light-absorbing compact phenothiazine-styrylBodipy electron donor/acceptor dyads: a better alternative to the heavy atom-effect?

2020 ◽  
Vol 56 (11) ◽  
pp. 1721-1724 ◽  
Author(s):  
Yuqi Hou ◽  
Qingyun Liu ◽  
Jianzhang Zhao
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Electron Donor ◽  
Heavy Atom ◽  
Red Light ◽  
Intersystem Crossing ◽  
Spin Orbital ◽  
Heavy Atom Effect ◽  
Donor Acceptor ◽  
Atom Effect

Heavy atom-free dyads showing a red light-absorbing and exceptionally long-lived triplet state based on a spin–orbital charge transfer intersystem crossing mechanism.

Triplet state quantum yields for some arom atic hydrocarbons and xanthene dyes in dilute solution

1967 ◽  
Vol 299 (1458) ◽  
pp. 348-353 ◽  
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Heavy Atom ◽  
Quantum Yields ◽  
Triplet States ◽  
Dilute Solution ◽  
Perturbation Techniques ◽  
Excited Singlet ◽  
Xanthene Dyes ◽  
Extinction Coefficients

Quantum yields of triplet state formation and extinction coefficients of the triplet states have been determined by direct depletion methods for solutions of anthracene, phenanthrene, 1,2,5,6-dibenzanthracene, fluorescein, dibromofluorescein, eosin and erythrosin. The values obtained for the hydrocarbons are in reasonable agreement with those obtained by other workers using energy transfer and heavy atom perturbation techniques. In all cases which we have studied, the sum of the quantum yields of fluorescence and triplet state formation is equal to unity within the limits of experimental error, showing that radiationless transfer from the excited singlet to the ground state is negligible.

scholarly journals Phosphoreszenzeigensch aften von Methyl-, Chlor- und Brom-Derivaten des [2.2] Paracyclophans

1987 ◽  
Vol 42 (9) ◽  
pp. 1041-1042 ◽  
Author(s):  
H. Hopf ◽  
E. Hermann
Keyword(s):  
Triplet State ◽  
Fluorescence Spectra ◽  
Heavy Atom ◽  
The Other ◽  
Quantum Yields ◽  
Heavy Atom Effect ◽  
Chloro Derivatives ◽  
Derivatives Of ◽  
Atom Effect

Phosphorescence and fluorescence spectra, quantum yields of phosphorescence and fluorescence as well as phosphorescence lifetimes have been measured of six methyl-, chloro- and bromo-derivatives of [2.2] paracyclophane in ethanol at 77 K. While the chloro-derivatives as well as dibromo-paracyclophane exhibit a normal internal heavy-atom effect behaviour the momobromo-compound shows anomalies. These possibly indicate that in the monobromo-compound an additional pathway of the radiationless deactivation of the lowest triplet state is effective which does not occur with the other compounds.

Identity-reaction proton transfers from oxygen acids yielding localized vs. delocalized conjugate bases. An ab initio study

1999 ◽  
Vol 77 (5-6) ◽  
pp. 810-816 ◽  
Author(s):  
James E Van Verth ◽  
William H Saunders, Jr.
Keyword(s):  
Proton Transfer ◽  
Ab Initio ◽  
Gas Phase ◽  
Heavy Atom ◽  
Proton Donor ◽  
Proton Transfers ◽  
Straight Line ◽  
Large Positive Deviation ◽  
Experimental Values ◽  
Conjugate Bases

Identity-reaction proton transfers from a series of oxygen acids to the corresponding conjugate bases have been studied by ab initio methods at the MP2/6-31+G*//MP2/6-31+G* level. The acids are H3O+, CH3OH2+, CH2 = OH+, HC(O)OH2+, CH2 = CHOH2+, H2O, CH3OH, HOOH, HOCH2OH, FOH, FCH2OH, HC(O)OH, and CH2 = CHOH. Gas-phase acidities were calculated at the G2(MP2) level in order to have benchmark values for all acidities regardless of whether experimental values were available. Barriers to proton transfer relative to the separated reactants, ΔHTS, show a straight-line relation to acidity for all but two of the neutral acids and for all but one of the cationic acids. Two neutral acids, HOOH and FOH, show negative deviations that can be attributed to polarizability of the atoms attached to the proton donor oxygens. The cationic acid HC(O)OH2+ shows a large positive deviation, which probably arises from substantial heavy-atom reorganization from reactant to TS. Charges provide evidence of a lag in delocalization in the reaction of CH2 = CHOH2+, though it does not show an elevated ΔHTS.Key words: ab initio, oxygen acids, proton transfer, acidity.

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