ChemInform Abstract: PHOTOCHEMICAL REACTIONS PART 10, EXTERNAL HEAVY-ATOM PERTURBED INTERSYSTEM CROSSING FROM THE EXCITED SINGLET AND TRIPLET STATES OF ANTHRACENE AND 9,10-DIBROMOANTHRACENE IN FLUID SOLUTION

A mechanism for the photolysis of acetone has been derived from experimental data including studies on the photosensitized isomerization of olefines. Dissociation into methyl and acetyl radicals occurs from both the first excited singlet and triplet states; the rate constants for excitation by light of 3130 Å wavelength are 2.5 x 10 16 exp ( —16900/ RT ) and 2.5 x 10 10 exp ( — 6400/ RT ) 1. mole -1 s -1 respectively. At low intensities of absorption, decomposition of acetyl radicals predominates over radical-radical interactions. The triplet state is extensively populated at moderate temperatures, the yield at 48 °C being 0.98. The low phosphorescence efficiency of acetone can be ascribed to intersystem crossing to the ground state for which the first order rate constant is 1.25 x 10 5 s -1 . The isomerization data requires the recognition of at least two vibrational levels of the acetone triplet, the rate of electronic energy transfer depending upon the excess energy possessed by the donor

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Photophysical Properties of Nitrated and Halogenated Phosphorus Tritolylcorrole Complexes: Insights from Theory

Molecules ◽

10.3390/molecules23112779 ◽

2018 ◽

Vol 23 (11) ◽

pp. 2779 ◽

Cited By ~ 4

Author(s):

Marta Alberto ◽

Bruna De Simone ◽

Gloria Mazzone ◽

Nino Russo ◽

Marirosa Toscano

Keyword(s):

Excited States ◽

Density Functional ◽

Energy Gap ◽

Photophysical Properties ◽

Intersystem Crossing ◽

Triplet States ◽

Excited Singlet ◽

Functional Theory ◽

The Density Functional Theory ◽

Singlet And Triplet States

The photophysical properties of a series of nitrated and halogenated phosphorus tritolylcorrole complexes were studied in dichloromethane solvent by using the density functional theory. Particular emphasis was given to the absorption spectra, the energy gap between the excited singlet and triplet states, and the magnitude of the spin-orbit couplings for a series of possible intersystem crossing channels between those excited states. The proposed study provides a better description of the photophysical properties of these systems while giving insights into their possible use as photosensitizers in photodynamic therapy.

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Photophysical and Photochemical Properties of Some Fluorescent Derivatives of Vitamin B1

Zeitschrift für Naturforschung A ◽

10.1515/zna-1987-0510 ◽

1987 ◽

Vol 42 (5) ◽

pp. 485-489 ◽

Cited By ~ 1

Author(s):

B. Marciniak

Keyword(s):

Vitamin B1 ◽

Emission Spectra ◽

Photochemical Reactions ◽

Triplet States ◽

Excited Singlet ◽

Yield Data ◽

Singlet And Triplet States ◽

Kinetics Of ◽

Derivatives Of ◽

Fluorescent Derivatives

Absorption and emission spectra, depopulation kinetics of the lowest excited singlet and triplet states and acid-base equilibria of two fluorescent vitamin B, derivatives, the products I and II of the reaction of N-methylated vitamine B, with cytidine and adenosine, respectively, were investigated. Analysis of the lifetime and quantum yield data indicate that at 77 K emissions are the main processes of deactivation of the S1 and T1 states for the free ion and protonated forms. The pKa values indicate a much higher acidity in the excited singlet and triplet states than in the ground state. I and II undergo very slow photochemical reactions in solution in the presence of oxygen (Φ ~ 10-4).

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ChemInform Abstract: Tuning the Photophysical Properties of anti-B18H22: Efficient Intersystem Crossing Between Excited Singlet and Triplet States in New 4,4′-(HS)2-anti-B18H20.

ChemInform ◽

10.1002/chin.201342009 ◽

2013 ◽

Vol 44 (42) ◽

pp. no-no

Author(s):

Josep M. Oliva ◽

et al. et al.

Keyword(s):

Photophysical Properties ◽

Intersystem Crossing ◽

Triplet States ◽

Excited Singlet ◽

Singlet And Triplet States

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Unexpectedly Long Lifetime of the Excited State of Benzothiadiazole Derivative and Its Adducts with Lewis Acids

Molecules ◽

10.3390/molecules26072030 ◽

2021 ◽

Vol 26 (7) ◽

pp. 2030

Author(s):

Taisiya S. Sukhikh ◽

Radmir M. Khisamov ◽

Sergey N. Konchenko

Keyword(s):

Lewis Acids ◽

Bromine Atom ◽

Heavy Atom ◽

Intersystem Crossing ◽

Triplet States ◽

X Ray Diffraction ◽

X Ray ◽

Singlet And Triplet States ◽

Long Lifetime ◽

Atom Effect

We report a study of photoluminescent properties of 4-bromo-7-(3-pyridylamino)-2,1,3-benzothiadiazole (Py-btd) and its novel Lewis adducts: (PyH-btd)2(ZnCl4) and [Cu2Cl2(Py-btd)2{PPO}2]·2C7H8 (PPO = tetraphenyldiphosphine monoxide), whose crystal structure was determined by X-ray diffraction analysis. Py-btd exhibits a lifetime of 9 microseconds indicating its phosphorescent nature, which is rare for purely organic compounds. This phenomenon arises from the heavy atom effect: the presence of a bromine atom in Py-btd promotes mixing of the singlet and triplet states to allow efficient singlet-to-triplet intersystem crossing. The Lewis adducts also feature a microsecond lifetime while emitting in a higher energy range than free Py-btd, which opens up the possibility to color-tune luminescence of benzothiadiazole derivatives.

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